| Match 1 (1):
Reference (000026 .. 000079, of 28480): |
Subject (000023 .. 000075, of 22118): |
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Both Charles Darwin himself and contemporary neo Darwinists such as Francisco Ayala Richard Dawkins and Richard Lewontin acknowledge that biological organisms appear to have been designed by an intelligence Yet classical Darwinists and contemporary Darwinists alike have argued that what Francisco Ayala calls the obvious design of living things is only apparent As Ayala |
Both Darwin himself and contemporary neo Darwinists such as Francisco Ayala Richard Dawkins and Richard Lewontin acknowledge that biological organisms appear to have been designed by an intelligence Yet classical Darwinists and contemporary Darwinists alike have argued that what Francisco Ayala calls the obvious design of living things is only apparent As Ayala |
| Match 2 (1):
Reference (000082 .. 000155, of 28480): |
Subject (000077 .. 000147, of 22118): |
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president of the American Association for the Advancement of Science has explained The functional design of organisms and their features would therefore seem to argue for the existence of a designer It was Darwin s greatest accomplishment to show that the directive organization of living beings can be explained as the result of a natural process natural selection without any need to resort to a Creator or other external agent 1 According to Darwin |
president of the American Association for the Advancement of Science has explained The functional design of organisms and their features would therefore seem to argue for the existence of a designer It was Darwin s greatest accomplishment to show that the directive organization of living beings can be explained as the result of a natural process natural selection without any need to resort to a Creator or other external agent Darwin |
| Match 3 (1):
Reference (000152 .. 000168, of 28480): |
Subject (000164 .. 000180, of 22118): |
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1 According to Darwin and his contemporary followers the mechanism of natural selection acting on random variation |
1 According to Darwin and his contemporary followers the mechanism of natural selection acting on random variation |
| Match 4 (1):
Reference (000171 .. 000191, of 28480): |
Subject (000182 .. 000204, of 22118): |
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to explain the origin of those features of life that once seemed to require explanation by reference to an intelligent or |
to explain the origin of those features of life that once seemed to require explanation by reference to an intelligent designer Thus according |
| Match 5 (1):
Reference (000171 .. 000242, of 28480): |
Subject (000182 .. 000250, of 22118): |
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to explain the origin of those features of life that once seemed to require explanation by reference to an intelligent or purposeful designer Thus according to 323 Darwinists the design hypothesis now represents an unnecessary and unparsimonious explanation for the complexity and apparent design of living organisms On these as well as methodological grounds contemporary biologists have generally excluded the design hypothesis from consideration as an explanation for the origin of biological |
to explain the origin of those features of life that once seemed to require explanation by reference to an intelligent designer Thus according to Darwinists the design hypothesis now represents an unnecessary and unparsimonious explanation for the complexity and apparent design of living organisms On these as well as methodological grounds contemporary biologists have generally excluded the design hypothesis from consideration as an explanation for the origin of biological |
| Match 6 (1):
Reference (000244 .. 000352, of 28480): |
Subject (000252 .. 000369, of 22118): |
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Yet does Darwinism in either its classical or contemporary versions fully succeed in explaining the origin of biological form Can it explain all evidence of apparent design Most biologists now acknowledge that the Darwinian mechanism of natural selection acting on random variations can explain small scale microevolutionary changes such as cyclical variations in the size of the beaks of Galapagos finches or reversible changes in the expression of genes controlling color in English peppered moths 2 But what about the large scale innovations in the history of life What about the origin of completely new organs body plans and structures the macroevolutionary innovation to which the fossil record attests |
Yet does Darwinism in either its classical or contemporary versions fully succeed in explaining the origin of biological form and function Can it explain all evidence of apparent design Most biologists now acknowledge that the Darwinian mechanism of natural selection acting on random variations can explain small scale micro evolutionary changes such as cyclical variations in the size of the beaks of Galapagos finches or reversible changes in the expression of genes controlling color in English peppered moths 2 But what about the origin of the larger scale innovations in the history of life What about the origin of completely new organs body plans and structures What about the macro evolutionary innovation to which the fossil record attests |
| Match 7 (1):
Reference (000354 .. 000383, of 28480): |
Subject (000371 .. 000398, of 22118): |
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Darwinism or neo Darwinism or any other strictly materialistic model of evolutionary change explain the origin of the basic body plans or structural designs of animal life without invoking actual |
Darwinism or neo Darwinism or any other model of evolutionary change explain the origin of the basic body plans or structural designs of animal life without invoking actual |
| Match 8 (1):
Reference (000406 .. 000418, of 28480): |
Subject (000415 .. 000426, of 22118): |
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of evolutionary theory punctuated equilibrium and self organization We will do so by |
of evolutionary theory known as punctuated equilibrium We will do so by |
| Match 9 (1):
Reference (000428 .. 000441, of 28480): |
Subject (000443 .. 000456, of 22118): |
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of the Cambrian explosion a term that refers to the geologically sudden appearance of |
of the Cambrian explosion a term that refers to the geologically sudden appearance of |
| Match 10 (1):
Reference (000449 .. 000468, of 28480): |
Subject (000462 .. 000481, of 22118): |
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body plans 530 million years ago We shall show that the Cambrian fossil record contradicts the empirical expectations of both |
body plans 530 million years ago We shall show that the Cambrian fossil record contradicts the empirical expectations of both |
| Match 11 (1):
Reference (000464 .. 000473, of 28480): |
Subject (006422 .. 006430, of 22118): |
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the empirical expectations of both neo Darwinism and punctuated equilibrium |
the empirical expectations of neo Darwinism and punctuated equilibrium |
| Match 12 (1):
Reference (000474 .. 000489, of 28480): |
Subject (000484 .. 000500, of 22118): |
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in several significant respects We further show that neither neo Darwinism s selection mutation mechanism nor |
in several significant respects We will further show that neither neo Darwinism s selection mutation mechanism nor |
| Match 13 (1):
Reference (000554 .. 000575, of 28480): |
Subject (000561 .. 000584, of 22118): |
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The term Cambrian explosion describes the geologically sudden appearance of animals in the fossil record during the Cambrian period of geologic time |
The term Cambrian Explosion describes the geologically sudden appearance of multi cellular animals in the fossil record during the Cambrian period of geologic time |
| Match 14 (1):
Reference (000591 .. 000601, of 28480): |
Subject (000597 .. 000607, of 22118): |
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phyla made their first appearance on earth 3 Phyla constitute the |
phyla first made their appearance on earth 3 Phyla constitute the |
| Match 15 (1):
Reference (000606 .. 000673, of 28480): |
Subject (000608 .. 000677, of 22118): |
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highest biological categories in the animal kingdom with each phylum exhibiting a unique architecture blueprint or structural body plan Familiar examples of basic animal body plans are cnidarians corals and jellyfish mollusks squids and shellfish arthropods crustaceans insects and trilobites echinoderms sea star and sea urchins and the chordates the phylum to which all vertebrates including humans belong The fossils of the Cambrian explosion exhibit several distinctive features |
highest biological categories or taxa in the animal kingdom with each phylum exhibiting a unique architecture blueprint or structural body plan Familiar examples of basic animal body plans are cnidarians corals and jellyfish mollusks squids and shellfish arthropods crustaceans insects and trilobites echinoderms sea star and sea urchins and the chordates the phylum to which all vertebrates including humans belong The fossils of the Cambrian explosion exhibit several distinctive features |
| Match 16 (1):
Reference (000687 .. 000709, of 28480): |
Subject (000678 .. 000700, of 22118): |
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First as the name implies the fossils of the Cambrian explosion appear suddenly or abruptly within a very brief period of geologic time |
First as the name implies the fossils of the Cambrian explosion appear suddenly or abruptly within a very brief period of geologic time |
| Match 17 (1):
Reference (000711 .. 000731, of 28480): |
Subject (000702 .. 000721, of 22118): |
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figures 1 and 2 As recently as 1992 paleontologists thought the Cambrian period began 570 million years ago and ended 510 |
Figure 1 As recently as 1992 paleontologists thought the Cambrian period began 570 million years ago mya and ended 510 |
| Match 18 (1):
Reference (000735 .. 000793, of 28480): |
Subject (000723 .. 000781, of 22118): |
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with the Cambrian explosion itself occurring within a 20 to 40 million year window during the lower Cambrian period In 1993 radiometric dating of zircon crystals from formations just above and just below Cambrian strata in Siberia allowed for a precise recalibration of the age of Cambrian strata Radiometric analyses of these crystals fixed the start of the Cambrian |
with the Cambrian explosion itself occurring within a 20 to 40 million year window during the lower Cambrian period In 1993 radiometric dating of zircon crystals from formations just above and just below Cambrian strata in Siberia allowed for a precise recalibration of the age of Cambrian strata Radiometric analyses of these crystals fixed the start of the Cambrian |
| Match 19 (1):
Reference (000735 .. 000795, of 28480): |
Subject (000723 .. 000781, of 22118): |
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with the Cambrian explosion itself occurring within a 20 to 40 million year window during the lower Cambrian period In 1993 radiometric dating of zircon crystals from formations just above and just below Cambrian strata in Siberia allowed for a precise recalibration of the age of Cambrian strata Radiometric analyses of these crystals fixed the start of the Cambrian The Cambrian |
with the Cambrian explosion itself occurring within a 20 to 40 million year window during the lower Cambrian period In 1993 radiometric dating of zircon crystals from formations just above and just below Cambrian strata in Siberia allowed for a precise recalibration of the age of Cambrian strata Radiometric analyses of these crystals fixed the start of the Cambrian |
| Match 20 (1):
Reference (000812 .. 000823, of 28480): |
Subject (009750 .. 009756, of 22118): |
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of the major animal groups phyla that first appeared in the Cambrian |
of the animal phyla in the Cambrian |
| Match 21 (1):
Reference (000870 .. 000903, of 28480): |
Subject (000807 .. 000838, of 22118): |
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figure 2 4 These studies also showed that the Cambrian explosion occurred within an exceedingly narrow window of geologic time lasting no more than 5 million years Geologically speaking 5 million years represents a |
Figure 2 These studies also showed that Cambrian explosion occurred within an exceedingly narrow window of geologic time lasting no more than 5 million years Geologically speaking 5 million years represents an |
| Match 22 (1):
Reference (000908 .. 000951, of 28480): |
Subject (000842 .. 000885, of 22118): |
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of Earth s history As Chinese paleontologist Jun Yuan Chen has explained compared with the 3 plus billion year history of life on earth the period of the explosion can be likened to one minute in 24 hours of one day 5 Yet most |
of the Earth s history As Chinese paleontologist Chen Junyuan has explained compared with the 3 plus billion year history of life on earth the period of the explosion can be likened to one minute in 24 hours of one day 5 Yet almost |
| Match 23 (1):
Reference (000961 .. 001086, of 28480): |
Subject (000896 .. 001021, of 22118): |
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forms occurred abruptly within just such a small fraction of the earth s history during the Cambrian Due to the suddenness of the appearance of animal life in the Cambrian the Cambrian explosion has now earned titles such as The Big Bang of Animal Evolution Scientific American Evolution s Big Bang Science and the Biological Big Bang Science News 6 To say that the fauna of the Cambrian period appeared in a geologically sudden manner also implies the absence of clear transitional intermediates connecting the complex Cambrian animals with those simpler living forms found in lower strata Indeed in almost all cases the body plans and structures present in Cambrian period animals have no clear morphological antecedents in earlier strata Some have argued that perhaps the |
forms occurred abruptly within just such a small fraction of the earth s history during the Cambrian Due to the suddenness of the appearance of animal life in the Cambrian the Cambrian explosion has now earned titles such as The Big Bang of Animal Evolution Scientific American Evolution s Big Bang Science and the Biological Big Bang Science News 6 To say that the fauna of the Cambrian period appeared in a geologically sudden manner also implies the absence of clear transitional intermediates connecting the complex Cambrian animals with those simpler living forms found in lower strata Indeed in almost all cases the body plans and structures present in Cambrian period animals have no clear morphological antecedents in earlier strata Some have argued that perhaps the |
| Match 24 (1):
Reference (001131 .. 001140, of 28480): |
Subject (000814 .. 000824, of 22118): |
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Cambrian explosion occurred within a narrow window of geologic time |
Cambrian explosion occurred within an exceedingly narrow window of geologic time |
| Match 25 (1):
Reference (001193 .. 001205, of 28480): |
Subject (001084 .. 001096, of 22118): |
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Second the Cambrian explosion exhibits an extraordinary morphological breadth and representation of the |
Second the Cambrian explosion exhibits an extraordinary morphological breadth and completeness at the |
| Match 26 (1):
Reference (001216 .. 001229, of 28480): |
Subject (001106 .. 001119, of 22118): |
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of the basic body plans or architectural designs of the animal kingdom Representatives of |
of the basic body plans or architectural designs of the animal kingdom Representatives of |
| Match 27 (1):
Reference (001255 .. 001268, of 28480): |
Subject (006157 .. 006168, of 22118): |
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the Precambrian Six animal phyla first appear in the fossil record after the Cambrian |
the phyla that first appear in the fossil record after the Cambrian |
| Match 28 (1):
Reference (001327 .. 001340, of 28480): |
Subject (001177 .. 001190, of 22118): |
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All living phyla may have originated by the end of the Cambrian explosion 8 |
All living phyla may have originated by the end of the Cambrian explosion 8 |
| Match 29 (1):
Reference (001327 .. 001343, of 28480): |
Subject (001177 .. 001192, of 22118): |
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All living phyla may have originated by the end of the Cambrian explosion 8 An especially dramatic |
All living phyla may have originated by the end of the Cambrian explosion 8 Especially dramatic |
| Match 30 (1):
Reference (001345 .. 001369, of 28480): |
Subject (001186 .. 001210, of 22118): |
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of the Cambrian explosion is the first appearance of all the invertebrate phyla and subphyla with mineralized exoskeletons including the advanced metazoans such as Mollusca |
of the Cambrian explosion 8 Especially dramatic is the appearance of all the invertebrate phyla with mineralized exoskeletons including the advanced metazoa such as Mollusca |
| Match 31 (1):
Reference (001403 .. 001443, of 28480): |
Subject (001211 .. 001250, of 22118): |
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Echinodermata and Arthropoda Trilobites see figure 3 a subphylum of Arthropoda were highly complex animals whose thoraxes comprised three lobes or sections a medial axial ring and two lateral pleurae The bodies of trilobites were covered by a shieldlike keratinized exoskeleton |
Echinodermata and Arthropoda Trilobites a subphylum of Arthropoda were highly complex animals whose thoraxes comprised three lobes or sections a medial axial ring and two lateral pleurae The bodies of trilobites were covered by an outer shield like keratinized exoskeleton |
| Match 32 (1):
Reference (001444 .. 001510, of 28480): |
Subject (001256 .. 001322, of 22118): |
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called a carapace which covered both the head and thorax of these animals Like modern arthropods trilobites grew by shedding their carapaces and these cast off carapaces help to account for the abundance of trilobite fossils The Chengjiang fauna also contains a number of fossils of now extinct top ofthe food chain predators with exotic names such as Anomalocaris up to six feet in length see figure |
called a carapace covered both the head and thorax of these animals Like modern arthropods trilobites grew by shedding their carapaces and these cast off carapaces help to account for the abundance of trilobite fossils The Chengjiang fauna also contains a number of fossils of now extinct top of the food chain predators with exotic names such as Anomolocaris up to six feet in length see Figure |
| Match 33 (1):
Reference (001509 .. 001549, of 28480): |
Subject (001331 .. 001370, of 22118): |
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see figure 4 which indicates the presence of a complex food web and a diverse ecological community Shelled animals leave a far more durable and extensive record than their soft bodied counterparts Nevertheless Cambrian fossil discoveries from both the Burgess shale |
see Figure 4 indicate the presence of a complex food web and a diverse ecological community Shelled animals leave a far more durable and extensive record than their soft bodied counterparts Nevertheless Cambrian fossil discoveries from both the Burgess shale |
| Match 34 (1):
Reference (001593 .. 001645, of 28480): |
Subject (001379 .. 001429, of 22118): |
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near Chengjiang China have also shown exquisitely preserved soft bodied fauna The Chengjiang fauna even show many excellent examples of well preserved animals with soft tissue animals lacking even a keratinized exoskeleton including members of phyla such as Cnidaria Ctenophora see figure 5 Annelida Onycophora Phoronida see figure 6 and Priapulida Burgess Shale |
near Chengjiang China have also shown exquisitely preserved soft bodied fauna The Chengjiang fauna even show many excellent examples of well preserved animals with soft tissue animals lacking even a keratinized exoskeleton 9 including members of still extant phyla such as Cnidaria Ctenophora Annelida Onycophora Phoronida and Priapulida The Burgess Shale |
| Match 35 (1):
Reference (001662 .. 001717, of 28480): |
Subject (001442 .. 001497, of 22118): |
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were long lived and geographically widespread The lower Cambrian sediments near Chengjiang have preserved fossils of such excellent quality that soft tissues and organs such as eyes intestines stomachs digestive glands sensory organs epidermis bristles mouths and nerves can be observed in detail Even fossilized embryos of sponges are present in the Precambrian strata near Chengjiang |
were long lived and geographically widespread The Lower Cambrian sediments near Chengjiang have preserved fossils of such excellent quality that soft tissues and organs such as eyes intestines stomachs digestive glands sensory organs epidermis bristles mouths and nerves can be observed in detail Even fossilized embryos of sponges are present in the Precambrian strata near Chengjiang |
| Match 36 (1):
Reference (001719 .. 001764, of 28480): |
Subject (001499 .. 001542, of 22118): |
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Cambrian level strata show the soft body parts of jellyfish like organisms known as Eldonia see figure 7 such as radiating water canals and nerve rings These fossils even include the gut contents of several different kinds of animals and undigested food residue in their stools |
Cambrian level strata show the soft body parts of jelly fish like organisms known as Eldonia such as radiating water canals and nerve rings These fossils even include the gut contents of several different kinds of animals and undigested food residue in their stools |
| Match 37 (1):
Reference (001800 .. 001833, of 28480): |
Subject (001544 .. 001578, of 22118): |
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The Chengjiang fauna also confirms the presence of animals from the phylum Chordata Yunnanozoon lividum is a fusiform eel shaped animal with among other features a digestive tract branchial arches and a large notochord |
The Chengjiang fauna also confirm the presence of animals from the Phylum Chordata including most prominently Yunnanozoon lividum a fusiform eelshaped animal with among other features a digestive tract branchial archers and a large notocord |
| Match 38 (1):
Reference (001912 .. 001936, of 28480): |
Subject (001603 .. 001627, of 22118): |
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have recently reported the discovery of a sophisticated craniate like chordate called Haikouella lancelota from the lower Cambrian Maotianshan Shale in China According to Chen |
have recently reported the discovery of a sophisticated craniate like chordate called Haikouella lancelota from the Lower Cambrian Maotianshan Shale in China According to Chen |
| Match 39 (1):
Reference (001940 .. 001985, of 28480): |
Subject (001630 .. 001675, of 22118): |
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Haikouella has many of the same features of the Yunnanozoon lividum as well as several additional anatomical features including a heart ventral and dorsal aorta an anterior branchial arterial gill filaments a caudal projection a neural cord with a relatively large brain a head with possible |
Haikouella has many of the same features of the Yunnanozoon lividum as well as several additional anatomic features including a heart ventral and dorsal aorta an anterior branchial arterial gill filaments a caudal projection a neural cord with a relatively large brain a head with possible |
| Match 40 (1):
Reference (002013 .. 002025, of 28480): |
Subject (001668 .. 001686, of 22118): |
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Iotuba chengjiangensis lateral eyes and a ventrally situated buccal cavity with short tentacles |
a relatively large brain a head with possible lateral eyes and a ventrally situated buccal cavity with short tentacles |
| Match 41 (1):
Reference (002031 .. 002052, of 28480): |
Subject (001689 .. 001710, of 22118): |
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Simon Conway Morris and several Chinese colleagues have made a dramatic find of two small fish fossils Myllokunmingia fengjiaoa and Haikouichthys ercaicunensis |
Simon Conway Morris and several Chinese colleagues have made a dramatic find of two small fish fossils Myllokunmingia fengjiaoa and Haikouichthys ercaicunensis |
| Match 42 (1):
Reference (002058 .. 002067, of 28480): |
Subject (001711 .. 001720, of 22118): |
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suggesting a much earlier appearance for vertebrates than previously thought |
suggesting a much earlier appearance for vertebrates than previously thought |
| Match 43 (1):
Reference (002388 .. 002480, of 28480): |
Subject (001781 .. 001873, of 22118): |
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A third feature of the Cambrian explosion as well as the subsequent fossil record bears mentioning The major body plans that arise in the Cambrian period exhibit considerable morphological isolation from one another or disparity and then subsequent stasis Though all Cambrian and subsequent animals fall clearly within one of a limited number of basic body plans each of these body plans exhibits clear morphological differences and thus disparity from the others 17 The animal body plans as represented in the fossil record do not grade imperceptibly one into another either at a |
A third feature of the Cambrian explosion as well as the subsequent fossil record bears mentioning The major body plans that arise in the Cambrian period exhibit considerable morphological isolation from one another or disparity and then subsequent stasis Though all Cambrian and subsequent animals fall clearly within one of a limited number of basic body plans 15 each of these body plans exhibit clear morphological differences and thus disparity from the others The animal body plans as represented in the fossil record do not grade imperceptibly one into another either at a |
| Match 44 (1):
Reference (002482 .. 002507, of 28480): |
Subject (001875 .. 001896, of 22118): |
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time in geological history or over the course of geological history Instead the body plans of the animals characterizing the separate phyla maintain their distinctive morphological |
time or over the course of geological history Instead the body plans of the animals characterizing the separate phyla maintain their morphological |
| Match 45 (1):
Reference (002549 .. 002644, of 28480): |
Subject (001966 .. 002061, of 22118): |
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In one sense of course the stasis of the phylum as an abstract morphological unit is unremarkable since phyla are defined for classificatory purposes by reference to an invariant set of anatomical characteristics In another sense however body plan stasis as it finds expression in actual animals is quite remarkable precisely because actual animals naturally do fall within one and only one of a disparate but limited number of classifi catory categories While the phyla as abstract classificatory units must by definition exhibit stasis the body plans of actual animals need not obey this definitional logic |
In one sense of course the morphological stasis of the phyla as an abstract morphological unit is unremarkable since phyla are defined for classificatory purposes by reference to an invariant set of anatomical characteristics In another sense however body plan stasis as it finds expression in actual animals is quite remarkable precisely because actual animals naturally do fall within one and only one of a disparate but limited number of classificatory categories While the phyla as abstract classificatory units must by definition exhibit stasis the body plans of actual animals need not obey this definitional logic |
| Match 46 (1):
Reference (002753 .. 002783, of 28480): |
Subject (002133 .. 002163, of 22118): |
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Fourth the sudden emergence of the various animals of the Cambrian explosion represents a dramatic discontinuous or quantum increase in the information content or specified complexity of the biological world For |
Fourth the sudden emergence of the various animals of the Cambrian explosion represents a dramatic discontinuous or quantum increase in the information content or specified complexity of the biological world For |
| Match 47 (1):
Reference (002785 .. 002849, of 28480): |
Subject (002165 .. 002228, of 22118): |
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billion years or five sixths of the earth s history the biological realm included little more than unicellular bacteria and blue green algae During this time some significant increases in complexity did occur About 2 7 billion years ago more complex eukaryotic cells cells with nuclei emerged after nearly 1 billion years of earth s history in which only prokaryotic cells existed on the earth |
billion years or five sixths of the earth s history the biological realm included little more than unicellular bacteria and bluegreen algae During this time some significant increases in complexity did occur About 2 7 billion years ago more complex eukaryotic cells cells with nuclei emerged after nearly 1 billion years of earth s history in which only prokaryotic cells existed on the earth |
| Match 48 (1):
Reference (002785 .. 002859, of 28480): |
Subject (002165 .. 002239, of 22118): |
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billion years or five sixths of the earth s history the biological realm included little more than unicellular bacteria and blue green algae During this time some significant increases in complexity did occur About 2 7 billion years ago more complex eukaryotic cells cells with nuclei emerged after nearly 1 billion years of earth s history in which only prokaryotic cells existed on the earth 21 About 1 billion years ago multicellular grade algae appeared |
billion years or five sixths of the earth s history the biological realm included little more than unicellular bacteria and bluegreen algae During this time some significant increases in complexity did occur About 2 7 billion years ago more complex eukaryotic cells cells with nuclei emerged after nearly 1 billion years of earth s history in which only prokaryotic cells existed on the earth 17 About one billion years ago multi cellular grade algae appeared |
| Match 49 (1):
Reference (002860 .. 002869, of 28480): |
Subject (002252 .. 002259, of 22118): |
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Then beginning about 565 570 million years ago in the |
Then beginning about 570 million years ago the |
| Match 50 (1):
Reference (002902 .. 002953, of 28480): |
Subject (002277 .. 002328, of 22118): |
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figures 1 and 2 Forty million years later the Cambrian explosion occurred Relative to the rather modest increases in complexity that occurred between the origin of the first life 3 5 to 3 85 billion years ago and the first appearance of multicellular algae 1 billion years ago the emergence of the |
Figures 1 and 2 Forty million years later the Cambrian explosion occurred Relative to the rather modest increases in complexity that occurred between the origin of the first life 3 5 3 85 billion years ago and the first appearance of multi cellular algae 1 billion years ago the emergence of the |
| Match 51 (1):
Reference (002957 .. 003006, of 28480): |
Subject (002331 .. 002382, of 22118): |
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570 million years ago and then to a much greater extent the Cambrian explosion 530 million years ago represent steep climbs up the biological complexity gradient Indeed analyzed from an informationtheoretic standpoint the Cambrian explosion in particular represents a remarkable jump in the specified information content of the biological world |
570 million years ago and then to a much greater extent the Cambrian explosion 530 million years ago represent steep climbs up the biological complexity gradient Indeed analyzed from an information theoretic standpoint the Cambrian explosion in particular represents a remarkable jump in the specified 18 information content of the biological world |
| Match 52 (1):
Reference (003344 .. 003362, of 28480): |
Subject (002370 .. 002389, of 22118): |
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increase in the specified complexity or specified information of the biological world One way to measure the increase in |
a remarkable jump in the specified 18 information content of the biological world One way to measure the increase in |
| Match 53 (1):
Reference (003367 .. 003401, of 28480): |
Subject (002391 .. 002425, of 22118): |
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complexity of the animals that appeared in the Cambrian is to assess the number of cell types that are required to build such animals and to compare that number with those creatures that went before |
complexity of the animals that appeared in the Cambrian is to assess the number of cell types that are required to build such animals and to compare that number with those creatures that went before |
| Match 54 (1):
Reference (003403 .. 003417, of 28480): |
Subject (002427 .. 002440, of 22118): |
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Functionally more complex animal forms require more cell types to perform their more diverse functions |
Functionally more complex animals require more cell types to perform their more diverse functions |
| Match 55 (1):
Reference (003431 .. 003471, of 28480): |
Subject (012642 .. 012682, of 22118): |
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Although specialized internally with a nucleus and various organelles the single celled eukaryote represents obviously a single type of cell Not so with the trilobite or mollusk where dozens of specific tissues and organs require functionally dedicated or specialized cell types |
Although specialized internally with a nucleus and various organelles the single celled eukaryote represents obviously a single type of cell Not so with the trilobite or mollusk where dozens of specific tissues and organs require functionally dedicated or specialized cell types |
| Match 56 (1):
Reference (003468 .. 003481, of 28480): |
Subject (012687 .. 012702, of 22118): |
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or specialized cell types But new cell types require many new and specialized proteins |
therefore requires at a minimum building novel cell types But cell types themselves require specialized proteins |
| Match 57 (1):
Reference (003485 .. 003519, of 28480): |
Subject (012704 .. 012740, of 22118): |
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epithelial cell lining a gut or intestine which secretes a digestive enzyme requires minimally structural proteins to modify its shape regulatory enzymes to control the secretion of the digestive enzyme and the digestive enzyme itself |
epithelial cell lining a gut or intestine which secretes a digestive enzyme for instance requires minimally structural proteins to modify its shape regulatory enzymes to control the secretion of the digestive enzyme and the digestive enzyme itself |
| Match 58 (1):
Reference (003521 .. 003562, of 28480): |
Subject (002450 .. 002495, of 22118): |
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proteins in turn require new genetic information encoded in DNA Thus an increase in the number of cell types implies at a minimum a considerable increase in the amount of specified genetic information Molecular biologists have recently estimated that a minimally complex |
proteins New proteins in turn require new genetic information encoded in DNA Thus an increase in the number of cell types implies at a minimum a considerable increase in the amount of specified genetic information For example molecular biologists have recently estimated that a minimally complex |
| Match 59 (1):
Reference (003587 .. 003599, of 28480): |
Subject (002502 .. 002514, of 22118): |
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562 kilobase pairs of DNA to produce the proteins necessary to maintain life |
562 kilobase pairs of DNA to produce the proteins necessary to maintain life |
| Match 60 (1):
Reference (003613 .. 003625, of 28480): |
Subject (002516 .. 002532, of 22118): |
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Yet to build the proteins necessary to sustain a complex animal would require |
Yet to build the proteins necessary to sustain a complex arthropod such as a trilobite would require |
| Match 61 (1):
Reference (003626 .. 003638, of 28480): |
Subject (002540 .. 002549, of 22118): |
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orders of magnitude more coding instructions For example the genome size of the |
orders of magnitude e g the genome size of the |
| Match 62 (1):
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of the fly Drosophila melanogaster an arthropod is approximately 120 million base pairs |
of the fly Drosophila melanogaster an arthropod is approximately 120 million base pairs |
| Match 63 (1):
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transitions from a single cell to colonies of cells to complex animals represent significant and in principle measurable increases in specified complexity or information content |
transitions from a single cell to colonies of cells to complex animals represent significant and in principle measurable increases in complexity and information content |
| Match 64 (1):
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Relative to the modest increases in specified complexity that occurred |
Relative to the rather modest increases in complexity that occurred |
| Match 65 (1):
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Indeed analyzed from an informational standpoint the Cambrian explosion represents a remarkable jump in the specified information |
Indeed analyzed from an information theoretic standpoint the Cambrian explosion in particular represents a remarkable jump in the specified 18 information |
| Match 66 (1):
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in the specified information or specified complexity of the biological world |
in the information content or specified complexity of the biological world |
| Match 67 (1):
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neo Darwinism and punctuated equilibrium against the Cambrian fossil record |
neo Darwinism and punctuated equilibrium the fossil record |
| Match 68 (1):
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Subject (002825 .. 002838, of 22118): |
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particular purport to offer truly creative mechanisms of biological change |
a neo Darwinism especially purports to offer a truly creative mechanism of biological change |
| Match 69 (1):
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the Cambrian fossils attest not only to small scale variations but also to large scale innovations in basic body plans the Cambrian data provide a key test to the efficacy of these |
the Cambrian fossils attest not only to small scale variations but also to large scale innovations in basic body plans the Cambrian data provide a key test of the |
| Match 70 (1):
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Subject (002919 .. 002935, of 22118): |
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According to neo Darwinism biological change occurs as natural selection acts on small random genetic changes and mutations |
According to neo Darwinism biological change occurs as natural selection acts on random genetic changes and mutations |
| Match 71 (1):
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Subject (002949 .. 002998, of 22118): |
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Over time small scale advantageous genetic changes accumulate eventually resulting in large scale changes in the morphology of organisms Thus according to neo Darwinism biological complexity should accumulate in a gradual bit by bit fashion over vast periods of geologic time A neo Darwinian understanding of the mechanism |
Over time small scale advantageous genetic changes accumulate eventually resulting in large scale changes in the morphology of organisms Thus according to a neo Darwinian account biological complexity should accumulate in a gradual bit by bit fashion over vast periods of geologic time A neo Darwinian understanding of the mechanism |
| Match 72 (1):
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generates new biological structure generates three specific predictions or empirical expectations concerning the fossil record Given the operation of the neo Darwinian mechanism the fossil record should show 1 the gradual emergence of biological complexity and the existence of numerous transitional forms leading to new phylum level body plans 2 small scale morphological diversity preceding the emergence of large scale morphological disparity and 3 a steady increase in the morphological distance between organic forms over time and consequently an overall steady increase in the number of phyla over time |
generating new biological structure generates three specific predictions or empirical expectations concerning the fossil record Given the operation of the neo Darwinian mechanism the fossil record should show 1 the gradual emergence of biological complexity and the existence of numerous transitional forms leading to new phyla level body plans 2 small scale morphological diversity preceding the emergence of large scale morphological disparity and 3 a steady increase in the morphological distance between organic forms over time and consequently a steady increase in the number of phyla over time |
| Match 73 (1):
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of testing both neo Darwinism and where applicable punctuated equilibrium A Prediction 1 The |
of neo Darwinism and punctuated equilibrium IV OBJECTIONS IV A The |
| Match 74 (1):
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A Prediction 1 The Gradual Emergence of Biological Complexity and the Existence of Numerous Transitional Forms Leading to Phyla Level Body Plans Charles Darwin regarded the sudden appearance of complex animals such as brachiopods and trilobites in the Cambrian strata |
A Prediction 1 The Gradual Emergence of Biological Complexity and the Existence of Numerous Transitional Forms Leading to Phyla Level Body Plans Charles Darwin regarded the sudden appearance of complex animals such as brachiopods and trilobites in the Cambrian fossil record as a |
| Match 75 (1):
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as a major challenge to his theory Based on his theory he expected to find intervening strata showing fossils of increasing complexity until finally trilobites appeared |
as a major challenge to his theory Based on his theory he expected to find intervening strata showing fossils of increasing complexity until finally trilobites appeared |
| Match 76 (1):
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Darwin realized that building highly complex animals such as trilobites from single celled organisms by natural selection operating on minute step by step variations would require a multitude of transitional forms and failed biological experiments over vast amounts of geologic time Accordingly he made the following prediction if the theory be true it is indisputable that before the lowest Cambrian stratum was deposited long periods elapsed as long as or probably far longer than the whole interval from the Cambrian age to the present day and that during these vast yet quite unknown periods of time the world swarmed with living creatures |
Darwin realized that building highly complex animals such as trilobites from single celled organisms by natural selection operating on minute step by step variations would require a multitude of transitional forms and failed biological experiments over vast amounts of geologic time Accordingly he made the following prediction if the theory be true it is indisputable that before the lowest Cambrian stratum was deposited long periods elapsed as long as or probably far longer than the whole interval from the Cambrian age to the present day and that during these vast yet quite unknown periods of time the world swarmed with living creatures |
| Match 77 (1):
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the amount of time that his theory required Geologists in Darwin s day employed relative dating methods They did not yet have modern radiometric methods for determining the absolute date of rocks Nevertheless Darwin had a clear picture of what his postulated selection variation mechanism implied about the history of life On his theory complex structures could only be built gradually minute improvement by minute improvement Thus natural selection would require vast periods of time to create new biological forms and structures Even in the |
the amount of time that his theory required Geologists in Darwin s day employed relative dating methods They did not yet have modern radiometric methods for determining the absolute date of rocks Nevertheless Darwin had a clear picture of what his postulated selection variation mechanism implied about the history of life On his theory complex structures could only be built gradually minute improvement by minute improvement Thus natural selection would require vast periods of time to create new biological forms and structures Even in the |
| Match 78 (1):
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the amount of time that his theory required Geologists in Darwin s day employed relative dating methods They did not yet have modern radiometric methods for determining the absolute date of rocks Nevertheless Darwin had a clear picture of what his postulated selection variation mechanism implied about the history of life On his theory complex structures could only be built gradually minute improvement by minute improvement Thus natural selection would require vast periods of time to create new biological forms and structures Even in the nineteenth century Darwin understood that this process would take many tens or hundreds of millions of years Modern neo Darwinists concur in this view As noted above neo Darwinism envisions minute changes in gene sequences accumulating very slowly as the result of random mutations |
the amount of time that his theory required Geologists in Darwin s day employed relative dating methods They did not yet have modern radiometric methods for determining the absolute date of rocks Nevertheless Darwin had a clear picture of what his postulated selection variation mechanism implied about the history of life On his theory complex structures could only be built gradually minute improvement by minute improvement Thus natural selection would require vast periods of time to create new biological forms and structures Even in the 19th century Darwin understood that this process would take many tens or hundreds of millions of years Modern neo Darwinists concur in this view As noted above neo Darwinism envisions minute changes in gene sequences accumulating very slowly as the result of random mutations |
| Match 79 (1):
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the amount of time that his theory required Geologists in Darwin s day employed relative dating methods They did not yet have modern radiometric methods for determining the absolute date of rocks Nevertheless Darwin had a clear picture of what his postulated selection variation mechanism implied about the history of life On his theory complex structures could only be built gradually minute improvement by minute improvement Thus natural selection would require vast periods of time to create new biological forms and structures Even in the nineteenth century Darwin understood that this process would take many tens or hundreds of millions of years Modern neo Darwinists concur in this view As noted above neo Darwinism envisions minute changes in gene sequences accumulating very slowly as the result of random mutations Yet empirically derived estimates of mutation rates in extant organisms suggest that the kind of large scale morphological changes that occurred in the Cambrian would have required far more time than the duration of the explosion |
the amount of time that his theory required Geologists in Darwin s day employed relative dating methods They did not yet have modern radiometric methods for determining the absolute date of rocks Nevertheless Darwin had a clear picture of what his postulated selection variation mechanism implied about the history of life On his theory complex structures could only be built gradually minute improvement by minute improvement Thus natural selection would require vast periods of time to create new biological forms and structures Even in the 19th century Darwin understood that this process would take many tens or hundreds of millions of years Modern neo Darwinists concur in this view As noted above neo Darwinism envisions minute changes in gene sequences accumulating very slowly as the result of random mutations Empirically derived estimates of mutation rates in extant organisms suggest that the kind of large scale morphological changes that occurred in the Cambrian would have required far more time than the duration of the explosion |
| Match 80 (1):
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al In addition to a pattern of gradual change Darwinist theories anticipate a gradual increase in the complexity and morphological diversity of organisms over time Clearly the fossil record does generally show an overall increase in the complexity of organisms from Precambrian to Cambrian times Nevertheless the fossil record does not show that novel organisms arose gradually nor does it document the existence of the many intermediate forms that Darwinian gradualism entails Indeed since the |
individual gene functions 25 In addition to a pattern of gradual change Darwinist theories anticipate a gradual increase in the complexity and morphological diversity of organisms over time Clearly the fossil record does show an overall increase in the complexity of organisms from Precambrian to Cambrian times Nevertheless the fossil record does not show that novel organisms arose gradually nor does it document the existence of the many intermediates forms that Darwinian gradualism entails Indeed since the |
| Match 81 (1):
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selection mechanism involves a trial and error process both Darwinism and neo Darwinism imply that the fossil record should show many transitional organisms and failed experiments |
selection mechanism involves a trial and error process both Darwinism and neo Darwinism imply that the fossil record should show many transitional organisms and failed experiments |
| Match 82 (1):
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Instead organisms such as trilobites phylum Arthropoda with their articulated body plans intricate nervous systems and compound eyes first appear fully formed at the beginning of the Cambrian explosion along with many other phyla of equal complexity |
Instead organisms such as Trilobites Phylum Arthropoda with their articulated body plans intricate nervous systems and compound eyes first appear fully formed at the beginning of the Cambrian explosion along with many other phyla of equal complexity |
| Match 83 (1):
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of equal complexity As Oxford zoologist Richard Dawkins acknowledges It is as though they the invertebrate phyla were just planted there without any evolutionary history |
of Oxford Zoologist Richard Dawkins It is as though they the invertebrate phyla were just planted there without any evolutionary history |
| Match 84 (1):
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Darwin was of course well aware even in the nineteenth century of the problem that the Cambrian explosion presented for his theory He stated The case at present must remain inexplicable and may be truly urged as a valid argument against the views here entertained |
Darwin was of course well aware even in the 19th century of the problem that the Cambrian explosion presented for his theory He stated The case at present must remain inexplicable and may be truly urged as a valid argument against the views here entertained |
| Match 85 (1):
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years since the publication of the Origin discoveries in paleontology have only made the puzzle of the Cambrian explosion more acute Not only have expected transitional forms not turned up but the pattern of the sudden appearance of novel structure has become more pronounced Massive new fossil discoveries in the rocks of the Burgess Shale in Canada and in the Yuanshan Formation |
years since the publication of the Origin of Species discoveries in paleontology have only made the puzzle of the Cambrian explosion more acute Not only have expected transitional forms not turned up but the pattern of the sudden appearance of novel structure has become more pronounced Massive new fossil discoveries in the rocks of the Burgess Shale in Canada and in the Yuanshan Formation |
| Match 86 (1):
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Chengjiang China have documented many previously unknown Cambrian phyla thus only increasing the number of expected and missing transitional intermediates required on a Darwinian account of the emergence of new living forms |
Chengjiang China have documented many previously unknown Cambrian phyla thus only increasing the number of expected and missing transitional intermediates required on a Darwinian account of the emergence of new living forms |
| Match 87 (1):
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The difficulty posed by the absence of transitional intermediates for both neo Darwinism and to a lesser but still significant extent punctuationalist evolutionary theories is illustrated |
The difficulty posed by the absence of transitional intermediates for both neo Darwinism and to a lesser but significant extent punctuationalist evolutionary theories is illustrated |
| Match 88 (1):
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morphological change versus time The first diagram shows the Darwinian and neo Darwinian expectation that changes in morphology should arise gradually as minute microevolutionary changes accumulate This Darwinian commitment to gradual change via microevolution produces the classic representation of the history of life as a branching tree figure |
morphological change versus time The first diagram shows the Darwinian and neo Darwinian expectation that changes in morphology should arise gradually as minute micro evolutionary changes accumulate This Darwinian commitment to gradual phyletic change via microevolution produces the classic representation of the history of life as a branching tree Figure |
| Match 89 (1):
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represents another model of strictly naturalistic evolutionary change as advanced by Niles Eldredge and Stephen J Gould This model known as punctuated equilibrium was developed during the late 1960s in an attempt to explain or describe more accurately the pattern of sudden appearance and stasis that paleontologists had long observed in the fossil record According to the punctuationalists evolutionary change occurs rapidly often after long periods of what they called stasis periods in which organisms manifest no directional change in |
represents another model of strictly naturalistic evolutionary change as advanced by Niles Eldredge and Stephen J Gould This model known as punctuated equilibrium was developed during the late 1960s in an attempt to explain or describe more accurately the pattern of sudden appearance and stasis that paleontologists had long observed in the fossil record According to the punctuationalists evolutionary change occurs rapidly often after long periods of what they called stasis periods in which organisms manifest no directional change in |
| Match 90 (1):
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their morphology By repudiating Darwinian gradualism this model specifically sought to account for the absence of transitional forms in the fossil record Even so insofar as this model maintained a commitment to the core Darwinian notion of common descent it too implied that the fossil record should preserve many intermediate forms |
their morphology By repudiating Darwinian gradualism this model specifically sought to account for the absence of transitional forms in the fossil record Even so in so far as this model maintained a commitment to the core Darwinian notion of common descent it too implied that the fossil record should preserve many intermediate forms |
| Match 91 (1):
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details how punctuationalists conceive of evolutionary change and thus also their expectations for what the fossil record ought to show According to many punctuationalists natural selection functions more as a mechanism for selecting the most fit species rather than the most fit individual among a species Thus morphological change should occur in larger more discrete intervals than traditional Darwinism asserts Nevertheless as figure |
details how punctuationalists conceive of evolutionary change and thus also their expectations for what the fossil record ought to show According to many punctuationalists natural selection functions more as a mechanism for selecting the most fit species rather than the most fit individual among a species Thus morphological change should occur in larger more discrete intervals than traditional Darwinism asserts Nevertheless as Figure |
| Match 92 (1):
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shows punctuationalists still envision many transitional forms as a result of a series of rapid evolutionary changes albeit representing larger jumps in morphology Figure |
shows punctuationalists still envision many transitional forms as a result of a series of rapid evolutionary changes albeit representing larger jumps in morphology The Figure |
| Match 93 (1):
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shows the relationship between time and morphology in the actual fossil record Note that contrary to the predicted patterns above the Cambrian radiation and subsequent variation occur after but not before the basic body plans appear in the fossil record The fossil record also shows a dearth of transitional intermediates between Cambrian and Precambrian fauna Since the late 1960s paleontologists have recognized that the general absence of transitional forms contradicts the picture of the history of life that neo Darwinism implies given its commitment to a gradualistic mechanism of evolutionary change |
shows the relationship between time and morphology in the actual fossil record Note that contrary to the predicted patterns above the Cambrian radiation and subsequent variation occurs after but not before the basic body plans appear in the fossil record The fossil record also shows a dearth of transitional intermediates between Cambrian and Precambrian fauna Since the late 1960s paleontologists have recognized that the general absence of transitional forms contradicts the picture of the history of life that neo Darwinism implies given its commitment to a gradualistic mechanism of evolutionary change |
| Match 94 (1):
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Fewer have recognized however that the absence of transitional forms also represents a severe |
Fewer have recognized however that the absence of transitional forms also represents a severe |
| Match 95 (1):
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relatively lesser difficulty for punctuated equilibrium Note that both standard neo Darwinian and more recent punctuationalist versions of evolutionary theory predict or expect many more transitional intermediates than the fossil record actually preserves This constitutes a particular difficulty because of the great number of new phyla represented in the Cambrian At present paleontologists lack clear ancestral precursors for the representatives of not just one new phylum but virtually all the phyla represented in Cambrian explosion |
relatively lesser difficulty for punctuated equilibrium Note that both standard neo Darwinian and more recent punctuationalist versions of evolutionary theory predict or expect many more transitional intermediates than the fossil record actually preserves This constitutes a particular difficulty because of the great number of new phyla represented in the Cambrian At present paleontologists lack clear ancestral precursors for the representatives of not just one new phyla but virtually all the phyla represented in Cambrian explosion |
| Match 96 (1):
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section IV B In a seminal paper titled Interpreting Great Developmental Experiments The Fossil Record |
section IV B below In a seminal paper titled Interpreting Great Developmental Experiments The Fossil Record |
| Match 97 (1):
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paleontologists J W Valentine and D H Erwin question the sufficiency of both evolutionary models discussed above as explanations for the origin of body plans and higher level taxa They note that transitional alliances are unknown or unconfirmed for any of the Cambrian phyla and yet the |
paleontologists J W Valentine and D H Erwin question the sufficiency of both evolutionary models discussed above as explanations for the origin of body plans and higher level taxa They note that transitional alliances are unknown or unconfirmed for any of the Cambrian phyla and yet the |
| Match 98 (1):
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evolutionary explosion near the beginning of Cambrian time was real and produced numerous new body plans Clearly neo Darwinism does not explain this pattern But as Valentine and Erwin point out neither does punctuated equilibrium |
evolutionary explosion near the beginning of Cambrian time was real and produced numerous new body plans 29 Clearly neo Darwinism does not explain this pattern But as Valentine and Erwin point out neither does punctuated equilibrium |
| Match 99 (1):
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note that the proposed mechanism of punctuated evolutionary change simply would have lacked the raw material upon which to work As Valentine and Erwin note the fossil record fails to document a large pool of species prior to the Cambrian Yet the proposed mechanism of species selection requires just such a pool of species upon which to act Thus they conclude that the probability that species selection is a general solution to the origin of higher taxa is not great |
note that the proposed mechanism of punctuated evolutionary change simply would have lacked the raw material upon which to work As Valentine and Erwin note the fossil record fails to document a large pool of species prior to the Cambrian Yet the proposed mechanism of species selection requires just such a pool of species upon which to act Thus they conclude that the probability that species selection is a general solution to the origin of higher taxa is not great |
| Match 100 (1):
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Recent work on statistical paleontology by Michael Foote of the University of Chicago |
Recent work on statistical paleontology by Michael Foote of the University of Chicago |
| Match 101 (1):
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develops a method by which evolutionary models can be tested against several variables Foote shows that given estimates of a completeness of the fossil record b median species duration c the time required for evolutionary transitions and d the number of ordinal or higher level transitions we could obtain an estimate of the number of major transitions we should expect to see in the fossil record His method provides a way to evaluate as he puts it whether the small number of documented major transitions provides strong evidence against evolution |
develops a method by which evolutionary models can be tested against several variables Foote shows that given estimates of a completeness of the fossil record b median species duration c the time required for evolutionary transitions and d the number of ordinal or higher level transitions we could obtain an estimate of the number of major transitions we should expect to see in the fossil record 31 His method provides a way to evaluate as he puts it whether the small number of documented major transitions provides strong evidence against evolution |
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of the completeness of the fossil record median species duration and the |
of the completeness of the Cambrian fossil record and the |
| Match 103 (1):
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transitions are reasonably well established the time required for plausible mechanisms to produce macroevolutionary transitions stands as the crucial variable in any such analysis If the time required to produce major evolutionary change is high as it is for neo Darwinian mechanisms of change then given current estimates of |
a b and d are reasonably well established c the time required for plausible mechanisms to produce macro evolutionary transitions stands as the crucial variable in any such analysis If the time required to produce major evolutionary change is high as it is for neo Darwinian mechanisms of change then given current estimates of |
| Match 104 (1):
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of the completeness of the fossil record median species duration and the |
of the completeness of the Cambrian fossil record and the |
| Match 105 (1):
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of ordinal or higherlevel transitions neo Darwinism fails to account for the data of the fossil record Conversely for punctuated equilibrium to succeed as an explanation for the data of the fossil record |
of a b and d neo Darwinism fails to account for the data of the fossil record Conversely for punctuated equilibrium to succeed as an explanation for the data of the fossil record |
| Match 106 (1):
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record the time required for plausible mechanisms to produce macroevolutionary transitions |
c the time required for plausible mechanisms to produce macro evolutionary transitions |
| Match 107 (1):
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must be very low In other words the explanatory success of punctuated equilibrium depends upon the existence of a mechanism that can produce rapid macroevolutionary change As Foote and Gould note elsewhere the punctuationalist model of Cambrian evolution requires a mechanism of unusual flexibility and speed |
must be very low In other words the explanatory success of punctuated equilibrium depends upon the existence of a mechanism that can produce rapid macro evolutionary change As Foote and Gould note elsewhere the punctuationalist model of Cambrian evolution requires a mechanism of unusual flexibility and speed |
| Match 108 (1):
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As yet however neither Foote nor Gould nor anyone else has identified such a mechanism with any genetic or developmental plausibility Thus given the current empirical climate the logic of Foote s statistical methodology tends to reinforce the earlier work of Valentine and |
As yet however neither Foote Gould nor anyone else has identified such a mechanism with any genetic or developmental plausibility Thus given the current empirical climate the logic of Foote s statistical methodology tends to reinforce the earlier work of Valentine and |
| Match 109 (1):
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Erwin who concluded that neither of the contending theories of evolutionary change at the species level phyletic gradualism or punctuated equilibrium seem applicable to the origin of new body plans and thus we now require a new theory for the evolution of novelty not diversity |
Erwin who concluded that neither of the contending theories of evolutionary change at the species level phyletic gradualism or punctuated equilibrium seem applicable to the origin of new body plans 34 and thus we now require a new theory for the evolution of novelty not diversity |
| Match 110 (1):
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B Prediction 2 Diversity Precedes Morphological Disparity contra Completeness and Morphological Breadth The distinction between small scale morphological diversity and large scale morphological novelty or what taxonomists call disparity raises another key issue Most biologists today believe that Darwinian mechanisms account for the great diversity of life by which they often mean the vast numbers of different species in existence Many fail to ask the question |
B Prediction 2 Diversity Precedes Morphological Disparity contra completeness and morphological breadth The distinction between small scale morphological diversity and large scale morphological novelty or what taxonomists call disparity raises another key issue Most biologists today believe that Darwinian mechanisms account for the great diversity of life by which they often mean the vast numbers of different species in existence Many fail to ask the question |
| Match 111 (1):
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disparity we mean the major differences in morphology in contrast to minor variations Specifically paleontologists use the term disparity to measure the major morphological differences between the body plans that correspond to the higher level taxonomic classifications whereas they use diversity to describe the small scale variations that correspond to lower level taxonomic classifications such as species or genera In other words disparity refers to life s basic morphological themes whereas diversity refers to the variations on those themes |
disparity By disparity we mean the major differences in morphology in contrast to minor variations Specifically paleontologists use the term disparity to measure the major morphological differences between the body plans that correspond to the higher level taxonomic classifications whereas they use diversity to describe the small scale variations that correspond to lower level taxonomic classifications such as species or genera In other words disparity refers to life s basic themes whereas diversity refers to the variations on those themes |
| Match 112 (1):
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According to neo Darwinism morphological distance between evolving organisms will increase gradually over time as small scale variations accumulate by natural selection to produce increasingly complex forms and structures including eventually new body plans Thus given the neo Darwinian mechanism one would expect that small scale differences or diversity between species should precede the emergence of morphological disparity between body plans and phyla see figures |
According to neo Darwinism morphological distance between evolving organisms will increase gradually over time as small scale variations accumulate by natural selection to produce increasingly complex forms and structures including eventually new body plans Thus given the neo Darwinian mechanism one would expect that small scale differences or diversity between species should precede the emergence of morphological disparity between body plans and phyla see Figures |
| Match 113 (1):
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As Richard Dawkins expresses the point What had been distinct species within one genus become in the fullness of time distinct genera within one family Later families will be found to have diverged to the point where taxonomists specialists in classification prefer to call them orders then classes then phyla Ancestors of two different phyla say vertebrates and mollusks which we see as built upon utterly different fundamental body plans were once just two species within a genus |
As Richard Dawkins expresses the point What had been distinct species within one genus become in the fullness of time distinct genera within one family Later families will be found to have diverged to the point where taxonomists specialists in classification prefer to call them orders then classes then phyla Ancestors of two different phyla say vertebrates and molluscs which we see as built upon utterly different fundamental body plans were once just two species within a genus |
| Match 114 (1):
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Indeed because the mutation selection mechanism operates cumulatively and gradually the novel body plans that define the different phyla must arise from numerous lower level speciation events For this reason neo |
Indeed because the selection variation mechanism operates cumulatively and gradually the novel body plans that define the different phyla must arise from numerous lower level speciation events For this reason neo |
| Match 115 (1):
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Subject (005259 .. 005297, of 22118): |
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Darwinism expects a cone of increasing diversity in which large scale morphological and taxonomic disparity results from the cumulative effects of many small scale speciation events Darwin himself made this point in the Origin Explaining his famous diagram figure |
Darwinism expects a cone of increasing diversity in which large scale morphological and taxonomic disparity results from the cumulative effects of many small scale speciation events Darwin himself made this point in the Origin Explaining his famous diagram Figure |
| Match 116 (1):
Reference (006580 .. 006605, of 28480): |
Subject (005299 .. 005324, of 22118): |
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illustrating the theory of common descent Darwin described how higher taxa should emerge from lower taxa by the accumulation of numerous slight variations As he said |
illustrating the theory of common descent Darwin described how higher taxa should emerge from lower taxa by the accumulation of numerous slight variations As he said |
| Match 117 (1):
Reference (006580 .. 006689, of 28480): |
Subject (005299 .. 005408, of 22118): |
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illustrating the theory of common descent Darwin described how higher taxa should emerge from lower taxa by the accumulation of numerous slight variations As he said T he diagram illustrates the steps by which small differences distinguishing varieties are increased into larger differences distinguishing species By continuing the process for a greater number of generations we get eight species He went on I see no reason to limit the process of modification as now explained to the formation of species and genera alone These two groups of genera will thus form two distinct families or orders according to the amount of divergent modification supposed to be represented in the diagram |
illustrating the theory of common descent Darwin described how higher taxa should emerge from lower taxa by the accumulation of numerous slight variations As he said the diagram illustrates the steps by which small differences distinguishing varieties are increased into larger differences distinguishing species By continuing the process for a greater number of generations we get eight species 38 He went on I see no reason to limit the process of modification as now explained to the formation of species and genera alone These two groups of genera will thus form two distinct families or orders according to the amount of divergent modification supposed to be represented in the diagram |
| Match 118 (1):
Reference (006691 .. 006711, of 28480): |
Subject (005410 .. 005430, of 22118): |
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Thus Darwin described small scale variations producing new species genera and orders This process would doubtless on a Darwinian view continue |
Thus Darwin described small scale variations producing new species genera and orders This process would doubtless on a Darwinian view continue |
| Match 119 (1):
Reference (006750 .. 006825, of 28480): |
Subject (005431 .. 005507, of 22118): |
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until it produced new phyla as well For both classical Darwinism and neo Darwinism diversity must precede disparity Phyla level differences in body plans must emerge therefore only after species genus and classlevel differences appear Though advocates of punctuationalist change envision morphological distance arising in larger more discrete intervals due to species selection than do classical neo Darwinists they too see phyla level differences arising cumulatively starting from lower level taxonomic differences between evolving forms In |
until it produced new phyla as well For both classical Darwinism and neo Darwinism diversity must precede disparity Phyla level differences in body plans must emerge therefore only after species genus and class level differences appear Though advocates of punctuationalist change envision morphological distance arising in larger more discrete intervals due to species selection than do classical neo Darwinists they too see phyla level differences arising cumulatively starting from lower level taxonomic differences between evolving forms In |
| Match 120 (1):
Reference (006827 .. 006837, of 28480): |
Subject (005509 .. 005519, of 22118): |
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words punctuated equilibrium also predicts morphological diversity preceding disparity as figure |
words punctuated equilibrium also predicts morphological diversity preceding disparity as Figure |
| Match 121 (1):
Reference (006839 .. 006872, of 28480): |
Subject (005521 .. 005559, of 22118): |
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also shows Thus for both current evolutionary models novel body plans are built bottomup as the result of many smaller scale genetic changes The actual pattern in the fossil record however contradicts this prediction |
also shows Thus for both current evolutionary models novel body plans disparity are built bottom up as the result of many smaller scale genetic changes i e diversity The actual pattern in the fossil record however contradicts this prediction |
| Match 122 (1):
Reference (006878 .. 006942, of 28480): |
Subject (005563 .. 005627, of 22118): |
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Instead of showing a gradual bottom up origin of the basic body plans where smaller scale diversification or speciation precedes the advent of large scale morphological disparity disparity precedes diversity Indeed the fossil record shows a top down pattern in which morphological disparity between many separate body plans emerges suddenly and prior to the occurrence of species level or higher diversification on those basic themes |
Instead of showing a gradual bottom up origin of the basic body plans where smaller scale diversification or speciation precedes the advent of large scale morphological disparity disparity precedes diversity Indeed the fossil record shows a top down pattern in which morphological disparity between many separate body plans emerges suddenly and prior to the occurrence of species level or higher diversification on those basic themes |
| Match 123 (1):
Reference (006943 .. 006997, of 28480): |
Subject (005633 .. 005687, of 22118): |
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As science writer Roger Lewin has noted Several possible patterns exist for the establishment of higher taxa the two most obvious of which are the bottom up and the top down approaches In the first evolutionary novelties emerge bit by bit The Cambrian explosion appears to conform to the second pattern the top down effect |
As science writer Roger Lewin has noted Several possible patterns exist for the establishment of higher taxa the two most obvious of which are the bottom up and the top down approaches In the first evolutionary novelties emerge bit by bit The Cambrian explosion appears to conform to the second pattern the top down effect |
| Match 124 (1):
Reference (007006 .. 007070, of 28480): |
Subject (005696 .. 005760, of 22118): |
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in their study of well skeletonized marine invertebrates Most higher taxa were built from the top down rather than from the bottom up The fossil record suggests that the major pulse of diversification of phyla occurs before that of classes classes before that of orders orders before that of families The higher taxa do not seem to have diverged through an accumulation of lower taxa |
in their study of well skeletonized marine invertebrates Most higher taxa were built from the top down rather than from the bottom up The fossil record suggests that the major pulse of diversification of phyla occurs before that of classes classes before that of orders orders before that of families The higher taxa do not seem to have diverged through an accumulation of lower taxa |
| Match 125 (1):
Reference (007072 .. 007087, of 28480): |
Subject (005762 .. 005775, of 22118): |
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In other words instead of a multiplication of species and other representatives of lower level taxa |
In other words instead of numerous species and other representatives of lower level taxa |
| Match 126 (1):
Reference (007089 .. 007102, of 28480): |
Subject (005777 .. 005788, of 22118): |
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first and the building to the disparity of higher taxa the highest taxonomic differences |
first building to the disparity of higher taxa the highest taxonomic differences |
| Match 127 (1):
Reference (007105 .. 007118, of 28480): |
Subject (005791 .. 005802, of 22118): |
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those between phyla and classes appear first instantiated by very few species level representatives |
those between phyla appear first instantiated by very few species level representatives |
| Match 128 (1):
Reference (007109 .. 007125, of 28480): |
Subject (005790 .. 005808, of 22118): |
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classes appear first instantiated by very few species level representatives Only later do lower level taxonomic differences |
e those between phyla appear first instantiated by very few species level representatives followed later by class level differences |
| Match 129 (1):
Reference (007140 .. 007149, of 28480): |
Subject (000286 .. 000294, of 22118): |
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the neo Darwinian mechanism of natural selection acting on random |
the Darwinian mechanism of natural selection acting on random |
| Match 130 (1):
Reference (007140 .. 007150, of 28480): |
Subject (002772 .. 002782, of 22118): |
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the neo Darwinian mechanism of natural selection acting on random genetic |
the neo Darwinian mechanism of natural selection acting on random genetic |
| Match 131 (1):
Reference (007140 .. 007151, of 28480): |
Subject (014308 .. 014316, of 22118): |
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the neo Darwinian mechanism of natural selection acting on random genetic mutations |
the mechanism of natural selection acting on random mutations |
| Match 132 (1):
Reference (007171 .. 007180, of 28480): |
Subject (021485 .. 021494, of 22118): |
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in the history of life following the Cambrian explosion C |
in the history of life following the Cambrian explosion Compare |
| Match 133 (1):
Reference (007180 .. 007194, of 28480): |
Subject (005939 .. 005954, of 22118): |
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C Prediction 3 The Morphological Distance between Organic Forms and thus the Number of Phyla |
C Prediction Number 3 The morphological distance between organic forms and thus the number of phyla |
| Match 134 (1):
Reference (007200 .. 007294, of 28480): |
Subject (005960 .. 006055, of 22118): |
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According to neo Darwinism and punctuated equilibrium the fossil record should exhibit another feature As we have seen the neo Darwinian mechanism and the punctuationalist mechanism of species selection imply that the morphological distance between organisms will increase gradually over time Thus both these mechanisms should produce a steadily increasing number of new body plans or phyla over time Borrowing from Darwin s predictions on the emergence of species see above we can express graphically the idealized expectation of the neo Darwinian and the punctuationalist model concerning the appearance of phyla over time see figure |
According to Darwinism neo Darwinism and punctuated equilibrium the fossil record should exhibit another feature As we have seen the neo Darwinian mechanism and the punctuationalist mechanism of species selection imply that the morphological distance between organisms will increase gradually over time Thus both these mechanisms should produce a steadily increasing number of new body plans or phyla over time Borrowing from Darwin s predictions on the emergence of species see above we can express graphically the idealized expectation of the neo Darwinian and the punctuationalist model concerning the appearance of phyla over time see Figure |
| Match 135 (1):
Reference (007297 .. 007325, of 28480): |
Subject (006062 .. 006090, of 22118): |
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both these evolutionary models the number of new phyla should increase in a steady logarithmic fashion as members of one phylum diversify and give rise to new phyla Figures |
both these evolutionary models the number of new phyla should increase in a steady logarithmic fashion as members of one phylum diversify and give rise to new phyla Figures |
| Match 136 (1):
Reference (007330 .. 007341, of 28480): |
Subject (006095 .. 006106, of 22118): |
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numerically the first appearance of all animal phyla over geological time Figure |
numerically the first appearance of all animal phyla over geological time Figure |
| Match 137 (1):
Reference (007344 .. 007359, of 28480): |
Subject (006109 .. 006124, of 22118): |
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the first appearance of animal phyla based solely on the present body of paleontological evidence Figure |
the first appearance of animal phyla based solely on the present body of paleontological evidence Figure |
| Match 138 (1):
Reference (007405 .. 007415, of 28480): |
Subject (006139 .. 006152, of 22118): |
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their first appearance in the Cambrian based on geological environmental considerations |
their first appearance in the Cambrian based on either evolutionary or geological environmental considerations |
| Match 139 (1):
Reference (007427 .. 007466, of 28480): |
Subject (006156 .. 006195, of 22118): |
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of the phyla that first appear in the fossil record after the Cambrian are less complex than the phyla that first appear in the Cambrian Since standard evolutionary reasoning assumes that complexity evolves from simplicity and not generally the reverse |
of the phyla that first appear in the fossil record after the Cambrian are less complex than the phyla that first appear in the Cambrian Since standard evolutionary reasoning assumes that complexity evolves from simplicity and not generally the reverse |
| Match 140 (1):
Reference (007473 .. 007521, of 28480): |
Subject (006202 .. 006252, of 22118): |
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assumed that these simpler phyla must have been present in the Cambrian Additionally factors such as organism size lifestyle habitat depositional environment and the presence or absence of mineralized hard parts affect the likelihood of preservation Many of the organisms representing phyla that first appear after the Cambrian or |
assumed that these simpler phyla must have been present in the Cambrian Additionally theoretically independent factors such as organism size lifestyle habitat depositional environment and the presence or absence of mineralized hard parts affect the likelihood of preservation Many of the organisms representing phyla that first appear after the Cambrian or |
| Match 141 (1):
Reference (007524 .. 007537, of 28480): |
Subject (006255 .. 006265, of 22118): |
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no fossil record at all have one or more of the above features that |
no fossil record at all have one or more features that |
| Match 142 (1):
Reference (007524 .. 007543, of 28480): |
Subject (006255 .. 006269, of 22118): |
|
no fossil record at all have one or more of the above features that would have rendered their preservation unlikely |
no fossil record at all have one or more features that render their preservation unlikely |
| Match 143 (1):
Reference (007580 .. 007591, of 28480): |
Subject (006342 .. 006349, of 22118): |
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of animals representing specific phyla that did first appear in the Cambrian |
of phyla that first appear during the Cambrian |
| Match 144 (1):
Reference (007666 .. 007677, of 28480): |
Subject (006272 .. 006283, of 22118): |
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factors suggest reasons independent of evolutionary assumptions for suspecting a Cambrian appearance |
factors suggest independent of evolutionary assumptions reasons for suspecting a Cambrian appearance |
| Match 145 (1):
Reference (007716 .. 007725, of 28480): |
Subject (006157 .. 006168, of 22118): |
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either first appear in the fossil record after the Cambrian |
the phyla that first appear in the fossil record after the Cambrian |
| Match 146 (1):
Reference (007740 .. 007750, of 28480): |
Subject (006312 .. 006323, of 22118): |
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can be excluded from a Cambrian first appearance given present knowledge |
can be definitively excluded from a Cambrian first appearance given present knowledge |
| Match 147 (1):
Reference (007854 .. 007873, of 28480): |
Subject (006324 .. 006343, of 22118): |
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Of course how one weighs and assesses these various factors will result in differing estimates for the number of phyla |
Of course how one weighs and assesses these various factors will result in differing estimates for the number of phyla |
| Match 148 (1):
Reference (007874 .. 007887, of 28480): |
Subject (006339 .. 006352, of 22118): |
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or phyla subphyla body plans that first appear during the Cambrian Values ranging from |
for the number of phyla that first appear during the Cambrian Values ranging from |
| Match 149 (1):
Reference (007894 .. 007907, of 28480): |
Subject (006359 .. 006372, of 22118): |
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are consistent with existing data Though we are skeptical of strictly presuppositionally driven arguments |
are consistent with existing data Though we are skeptical of strictly presuppositionally driven arguments |
| Match 150 (1):
Reference (007945 .. 007981, of 28480): |
Subject (006401 .. 006437, of 22118): |
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first appearances at both extremes of this range in order to show that however one assesses the various factors discussed above the empirical expectations of neo Darwinism and punctuated equilibrium do not conform to paleontological evidence concerning |
first appearance at both extremes of this range in order to show that however one assesses the various factors discussed above the empirical expectations of neo Darwinism and punctuated equilibrium do not conform to paleontological evidence concerning |
| Match 151 (1):
Reference (007984 .. 007998, of 28480): |
Subject (006439 .. 006453, of 22118): |
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first appearance Indeed rather than conforming to neo Darwinian and punctuationalist expectations of a steadily |
first appearance Indeed rather than conforming to neo Darwinian and punctuationalist expectations of a steadily |
| Match 152 (1):
Reference (008087 .. 008117, of 28480): |
Subject (006454 .. 006484, of 22118): |
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increasing number of phyla over geologic time the fossil record shows a very different pattern namely a sudden burst of phyla first appearing in the Cambrian followed either by as in |
increasing number of phyla over geologic time the fossil record shows a very different pattern namely a sudden burst of phyletic first appearance in the Cambrian followed either by as in |
| Match 153 (1):
Reference (008141 .. 008151, of 28480): |
Subject (006510 .. 006520, of 22118): |
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Indeed for 525 million years after the Cambrian explosion and for |
Indeed for 525 million years after the Cambrian explosion and for |
| Match 154 (1):
Reference (008153 .. 008172, of 28480): |
Subject (006522 .. 006541, of 22118): |
|
billion years before it the fossil record does not show anything like a steadily increasing number of new phyla Nor |
billion years before it the fossil record does not show anything like a steadily increasing number of new phyla Nor |
| Match 155 (1):
Reference (008291 .. 008305, of 28480): |
Subject (006564 .. 006578, of 22118): |
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fit the pattern of steady increase that one would expect given either of the two |
fit the pattern of steady increase that one would expect given either of the two |
| Match 156 (1):
Reference (008302 .. 008313, of 28480): |
Subject (004275 .. 004288, of 22118): |
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either of the two main evolutionary pictures of the history of life |
the general absence of transitional forms contradicts the picture of the history of life |
| Match 157 (1):
Reference (008314 .. 008326, of 28480): |
Subject (006582 .. 006594, of 22118): |
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We have provided two other graphs that reinforce these points Several animal phyla |
We have provided two other graphs that reinforce these points Several animal phyla |
| Match 158 (1):
Reference (008334 .. 008353, of 28480): |
Subject (006599 .. 006619, of 22118): |
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subphyla These subphyla represent major morphological divisions within their respective phyla distinctions even greater than those seen between classes Since |
subphyla These sub phyla represent major morphological divisions within their respective phyla distinctions even greater than those seen between classes Since |
| Match 159 (1):
Reference (008356 .. 008367, of 28480): |
Subject (006622 .. 006632, of 22118): |
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regard subphyla as equivalent or nearly equivalent to phyla we have also |
regard subphyla as nearly equivalent to phyla 47 we have also |
| Match 160 (1):
Reference (008374 .. 008394, of 28480): |
Subject (006638 .. 006658, of 22118): |
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to show the stratigraphic first appearance and presumed first appearance not only for all the animal phyla but also for the |
to show the stratigraphic first appearance and presumed first appearance not only for all the animal phyla but also for the |
| Match 161 (1):
Reference (008402 .. 008415, of 28480): |
Subject (006664 .. 006677, of 22118): |
|
graphs the first appearance of the phyla and subphyla on strictly empirical grounds Figure |
graphs the first appearance of the phyla and subphyla on strictly empirical grounds Figure |
| Match 162 (1):
Reference (008417 .. 008426, of 28480): |
Subject (006679 .. 006688, of 22118): |
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graphs the presumed first appearance of the phyla and subphyla |
graphs the presumed first appearance of the phyla and subphyla |
| Match 163 (1):
Reference (008512 .. 008521, of 28480): |
Subject (006137 .. 006146, of 22118): |
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have their first appearance in the Cambrian Estimates based on |
have had their first appearance in the Cambrian based on |
| Match 164 (1):
Reference (008674 .. 008693, of 28480): |
Subject (006712 .. 006731, of 22118): |
|
the pattern of first appearance of the phyla and subphyla contradicts that predicted by both the neo Darwinian and punctuationalist |
the pattern first appearance of the phyla and sub phyla contradicts that predicted by both the neo Darwinian and punctuationalist |
| Match 165 (1):
Reference (008698 .. 008848, of 28480): |
Subject (006731 .. 006883, of 22118): |
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al D Summary Assessment When we compare the pattern of fossilization in the actual fossil record to the expected pattern given the neo Darwinian mechanism we encounter significant dissonance Neither the pace nor the mode of evolutionary change match neo Darwinian expectations Indeed the neo Darwinism mechanism cannot explain the geologically sudden origin of the major body plans to which the term the Cambrian explosion principally refers Further the absence of plausible transitional organisms the pattern of disparity preceding diversity and the pattern of phyla first appearance all run counter to the neo Darwinian predictions or expectations Only the overall increase in complexity from the Precambrian to the Cambrian conforms to neo Darwinian expectations Although as we have seen the newer punctuationalist model of evolutionary change appears more consonant with some aspects of the Cambrian Precambrian fossil record it too fails to account for the extreme absence of transitional intermediates the |
punctuationalist mechanisms III D Summary Assessment When we compare the pattern of fossilization in the actual fossil record to the expected pattern given the neo Darwinian mechanism we encounter significant dissonance Neither the pace nor the mode of evolutionary change match neo Darwinian expectations Indeed the neo Darwinism mechanism cannot explain the geologically sudden origin of the major body plans to which the term the Cambrian explosion principally refers Further the absence of plausible transitional organisms the pattern of disparity preceding diversity and the pattern of phyletic first appearance all run counter to the neo Darwinian predictions or expectations Only the overall increase in complexity from the Precambrian to the Cambrian conforms to neo Darwinian expectations Though as we have seen the newer punctuationalist model of evolutionary change appears more consonant with some aspects of the Cambrian Precambrian fossil record it too fails to account for the extreme absence of transitional intermediates the |
| Match 166 (1):
Reference (008848 .. 008859, of 28480): |
Subject (006807 .. 006816, of 22118): |
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the top down pattern of disparity preceding diversity and the pattern of |
the pattern of disparity preceding diversity and the pattern of |
| Match 167 (1):
Reference (008861 .. 008956, of 28480): |
Subject (006893 .. 006988, of 22118): |
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first appearance Furthermore punctuated equilibrium lacks a sufficient mechanism to explain the origin of the major body plans that appear in the Cambrian strata These problems underscore a more significant theoretical difficulty for evolutionary theory generally namely the insufficiency of attempts to extrapolate microevolutionary mechanisms to explain macroevolutionary development As developmental biologists Gilbert Opitz and Raff have noted The Modern Synthesis is a remarkable achievement However starting in the 1970s many biologists began questioning its adequacy in explaining evolution Genetics might be adequate for explaining microevolution but microevolutionary changes in gene frequency were not seen as |
first appearance Furthermore punctuated equilibrium lacks a sufficient mechanism to explain the origin of the major body plans in the Cambrian strata These problems underscore a more significant theoretical difficulty for evolutionary theory generally namely the insufficiency of attempts to extrapolate microevolutionary mechanisms to explain macro evolutionary development As developmental biologists Gilbert Opitz and Raff have noted The Modern Synthesis is a remarkable achievement However starting in the 1970 s many biologists began questioning its adequacy in explaining evolution Genetics might be adequate for explaining microevolution but microevolutionary changes in gene frequency were not seen as |
| Match 168 (1):
Reference (009012 .. 009045, of 28480): |
Subject (006989 .. 007022, of 22118): |
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able to turn a reptile into a mammal or to convert a fish into an amphibian Microevolution looks at adaptations that concern only the survival of the fittest not the arrival of the fittest |
able to turn a reptile into a mammal or to convert a fish into an amphibian Microevolution looks at adaptations that concern only the survival of the fittest not the arrival of the fittest |
| Match 169 (1):
Reference (009047 .. 009108, of 28480): |
Subject (007024 .. 007085, of 22118): |
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Or as Roger Lewin stated in his summary of the historic Chicago Macroevolution conference in 1980 The central question of the Chicago conference was whether the mechanisms underlying microevolution can be extrapolated to explain the phenomena of macroevolution At the risk of doing violence to the position of some people at the meeting the answer can be given as a clear No |
Or as Roger Lewin stated in his summary of the historic Chicago Macroevolution Conference in 1980 The central question of the Chicago conference was whether the mechanisms underlying microevolution can be extrapolated to explain the phenomena of macroevolution At the risk of doing violence to the position of some people at the meeting the answer can be given as a clear No |
| Match 170 (1):
Reference (009118 .. 009143, of 28480): |
Subject (007095 .. 007119, of 22118): |
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increasingly recognized as an unsolved problem for all fully naturalistic versions of evolutionary theory and biologists especially developmental biologists are beginning an intensive search for solutions |
increasingly recognized as unsolved problems for all fully naturalistic versions of evolutionary theory and biologists especially developmental biologists are beginning an intensive search for solutions |
| Match 171 (1):
Reference (009145 .. 009181, of 28480): |
Subject (007121 .. 007152, of 22118): |
|
Before considering whether the theory of intelligent design should be considered in this search we will consider some objections to the paleontological arguments that we have marshaled against the adequacy of neo Darwinism and punctuated equilibrium IV |
Before considering whether intelligent design should be considered in this search we will consider some objections to arguments that we have marshaled against the adequacy of neo Darwinism and punctuated equilibrium IV |
| Match 172 (1):
Reference (009145 .. 009185, of 28480): |
Subject (007121 .. 007157, of 22118): |
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Before considering whether the theory of intelligent design should be considered in this search we will consider some objections to the paleontological arguments that we have marshaled against the adequacy of neo Darwinism and punctuated equilibrium IV Objections A The Artifact |
Before considering whether intelligent design should be considered in this search we will consider some objections to arguments that we have marshaled against the adequacy of neo Darwinism and punctuated equilibrium IV OBJECTIONS IV A The Artifact |
| Match 173 (1):
Reference (009189 .. 009217, of 28480): |
Subject (007161 .. 007188, of 22118): |
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Cambrian Explosion Real Many have argued that absence of Precambrian transitional intermediates does not disconfirm neo Darwinian predictions but instead testifies only to the incompleteness of the fossil record |
Cambrian Explosion Real Many have argued that absence of Precambrian transitional intermediates does not disconfirm neo Darwinian predictions but instead testifies to the incompleteness of the fossil record |
| Match 174 (1):
Reference (009215 .. 009245, of 28480): |
Subject (007190 .. 007220, of 22118): |
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the fossil record The difference between what the fossil record shows and what neo Darwinism implies that it should show has led many to question not the neo Darwinian mechanism or |
the difference between what the fossil record shows and what neo Darwinism implies that it should show has led many to question not the neo Darwinian mechanism but the fossil record |
| Match 175 (1):
Reference (009253 .. 009334, of 28480): |
Subject (007217 .. 007294, of 22118): |
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but the completeness of the fossil record Initially however Darwinists adopted a different approach For many decades after the publication of the Origin paleontologists sympathetic to Darwin s theory sought to find the missing ancestors of the Cambrian animals The search for the missing fossils in Precambrian formations all over the world resulted in universal disappointment Maintaining Darwin s theory therefore eventually required formulating ad hoc hypotheses to account for the absence of ancestral and transitional forms Various so called artifact hypotheses |
but the fossil record Initially however Darwinists adopted a different approach For many decades after the publication of the Origin of Species paleontologists sympathetic to Darwin s theory sought to find the missing ancestors of the Cambrian animals The search for the missing fossils in Precambrian formations all over the world resulted in universal disappointment Maintaining Darwin s theory therefore eventually required formulating ad hoc hypotheses to account for the absence of ancestral and transitional forms Various hypotheses |
| Match 176 (1):
Reference (009345 .. 009366, of 28480): |
Subject (007314 .. 007335, of 22118): |
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hold that the fossil ancestors existed but for various reasons were not preserved in an imperfect and biased fossil record On this |
holds that the fossil ancestors existed but for various reasons were not preserved in an imperfect and biased fossil record On this |
| Match 177 (1):
Reference (009368 .. 009377, of 28480): |
Subject (007337 .. 007346, of 22118): |
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the absence of the fossil ancestors represents an artifact of |
the absence of the fossil ancestors represents an artifact of |
| Match 178 (1):
Reference (009390 .. 009412, of 28480): |
Subject (007349 .. 007372, of 22118): |
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an accurate representation of the history of life Gaps in the fossil record are apparent not real A popular version of the artifact |
a not accurate representation of the history of life Gaps in the fossil record are apparent not real A popular version of the artifact |
| Match 179 (1):
Reference (009390 .. 009525, of 28480): |
Subject (007349 .. 007486, of 22118): |
|
an accurate representation of the history of life Gaps in the fossil record are apparent not real A popular version of the artifact hypothesis was proposed by the prominent American geologist Charles Walcott in the early 1900s Taking his lead from Darwin Walcott proposed a so called Lipalian interval According to Walcott the ancestors of the trilobites first lived and evolved at a time when the Precambrian seas had receded from the land masses Then at the beginning of the Cambrian the seas again rose covering the continents and depositing recently evolved trilobites According to Walcott ancestral trilobites did exist but were not fossilized in terrestrial sediments until the beginning of the Cambrian Before the Cambrian during a period of recession of seas trilobites and their ancestral forms were being deposited only in deep sea sediments |
a not accurate representation of the history of life Gaps in the fossil record are apparent not real A popular version of the artifact theory was proposed by the prominent American geologist Charles Walcott in the early 1900s Taking his lead from Darwin Walcott proposed a so called Lipalian interval According to Walcott the ancestors of trilobites first lived and evolved at a time when the Precambrian seas had receded from the land masses Then at the beginning of the Cambrian the seas again rose covering the continents and depositing the then recently evolved trilobites According to Walcott ancestral trilobites did exist but were not fossilized in terrestrial sediments until the beginning of the Cambrian Before the Cambrian during a period of recession of seas trilobites and their ancestral forms were being deposited only in deep sea sediments |
| Match 180 (1):
Reference (009529 .. 009609, of 28480): |
Subject (007490 .. 007570, of 22118): |
|
argued that paleontologists should not expect to find fossilized trilobites in terrestrial strata but only in the marine sediments that were in Walcott s time inaccessible to paleontology The Lipalian interval hypothesis had the advantage of accounting for the sudden appearance of the trilobites and the absence of ancestral and transitional forms Moreover it could be tested at least once offshore drilling technology advanced to allow for the sampling of the buried offshore Precambrian sedimentary rocks Walcotts s Lipalian interval hypothesis |
argued that paleontologists should not expect to find fossilized trilobites in terrestrial strata but only in the marine sediments that were in Walcott s time inaccessible to paleontology The Lipalian interval hypothesis had the advantage of accounting for the sudden appearance of the trilobites and the absence of ancestral and transitional forms Moreover it could be tested at least once off shore drilling technology advanced to allow for the sampling of the buried offshore sedimentary rocks Unfortunately for Walcott s hypothesis |
| Match 181 (1):
Reference (009618 .. 009634, of 28480): |
Subject (007572 .. 007588, of 22118): |
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technology has now been developed and offshore drilling cores have repeatedly failed to verify the existence of |
technology has now been developed and offshore drilling cores have repeatedly failed to verify the existence of |
| Match 182 (1):
Reference (009618 .. 009638, of 28480): |
Subject (007572 .. 007592, of 22118): |
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technology has now been developed and offshore drilling cores have repeatedly failed to verify the existence of Walcott s predicted fossils |
technology has now been developed and offshore drilling cores have repeatedly failed to verify the existence of the predicted Precambrian fossils |
| Match 183 (1):
Reference (009898 .. 009948, of 28480): |
Subject (007625 .. 007676, of 22118): |
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metamorphosed or melted beyond recognition Others claimed that major evolutionary innovation occurred during periods in which sedimentary deposition had ceased Advocates of these hypotheses abandoned them however once geologists began to uncover extensive Precambrian sedimentary deposits that again failed to document the existence of plausible ancestors for the complex Cambrian animals |
metamorphosed or melted beyond recognition Others have claimed that major evolutionary innovation occurred during periods in which sedimentary deposition had ceased Advocates of these hypotheses abandoned them however once geologists began to uncover extensive Precambrian sedimentary deposits that again failed to document the existence of plausible ancestors for the complex Cambrian animals |
| Match 184 (1):
Reference (009950 .. 009977, of 28480): |
Subject (007678 .. 007705, of 22118): |
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Proponents of the artifact hypothesis have advanced other explanations One asserts that the Precambrian ancestors of the Cambrian animals lacked hard parts such as shells and exoskeletons Thus |
Proponents of the artifact theory have advanced other explanations One asserts that the Precambrian ancestors of the Cambrian animals lacked hard parts such as shells and exoskeletons Thus |
| Match 185 (1):
Reference (009986 .. 010000, of 28480): |
Subject (007706 .. 007720, of 22118): |
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we should not expect to find remains of ancestral forms in the Precambrian fossil record |
we should not expect to find remains of these ancestral forms in the fossil record |
| Match 186 (1):
Reference (010018 .. 010041, of 28480): |
Subject (007721 .. 007744, of 22118): |
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While clearly the fossil record does not preserve soft body parts of organisms as frequently as hard body parts it has preserved enough soft |
While clearly the fossil record does not preserve soft body parts of organisms as frequently as hard body parts it has preserved enough soft |
| Match 187 (1):
Reference (010043 .. 010052, of 28480): |
Subject (007746 .. 007755, of 22118): |
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animals and organs to render this version of the artifact |
animals and organs to render this version of the artifact |
| Match 188 (1):
Reference (010043 .. 010055, of 28480): |
Subject (007746 .. 007758, of 22118): |
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animals and organs to render this version of the artifact hypothesis suspect Indeed |
animals and organs to render this version of the artifact theory suspect Indeed |
| Match 189 (1):
Reference (010088 .. 010128, of 28480): |
Subject (007783 .. 007823, of 22118): |
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represent plausible transitional intermediates to representatives of the Cambrian phyla In each case the jump in complexity as measured by the number of cell types for example and the morphological disparity between the Precambrian and Cambrian organisms appear far too great |
represent plausible transitional intermediates to representatives of the Cambrian phyla In each case the jump in complexity as measured by the number of cell types for example and the morphological disparity between the Precambrian and Cambrian organisms appears far too great |
| Match 190 (1):
Reference (010133 .. 010150, of 28480): |
Subject (007824 .. 007841, of 22118): |
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Furthermore the postulation of exclusively soft bodied ancestors for hard bodied Cambrian organisms seems implausible on anatomical grounds |
Furthermore the postulation of exclusively soft bodied ancestors for hard bodied Cambrian organisms seems implausible on anatomical grounds |
| Match 191 (1):
Reference (010152 .. 010199, of 28480): |
Subject (007843 .. 007888, of 22118): |
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Many phyla such as brachiopods and arthropods could have not evolved their soft parts first and then added shells later since their survival depends in large part upon their ability to protect their soft parts from hostile environmental forces Instead soft and hard parts had to arise together |
Many phyla such as brachiopods could have not evolved their soft parts first and then added shells later since their survival depends in large part upon their ability to protect their soft parts from hostile environmental forces Instead soft and hard parts had to arise together |
| Match 192 (1):
Reference (010224 .. 010252, of 28480): |
Subject (007906 .. 007934, of 22118): |
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To admit that hard bodied Cambrian animals had not yet evolved their hard bodied parts in the Precambrian effectively concedes that credible precursor animals themselves had not yet evolved |
To admit that hard bodied Cambrian animals had not yet evolved their hard bodied parts in the Precambrian effectively concedes that credible precursor animals themselves had not yet evolved |
| Match 193 (1):
Reference (010254 .. 010329, of 28480): |
Subject (007936 .. 008010, of 22118): |
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As Chen and Zhou explain A nimals such as brachiopods and most echinoderms and mollusks cannot exist without a mineralized skeleton Arthropods bear jointed appendages and likewise require a hard organic or mineralized outer covering Therefore the existence of these organisms in the distant past should be recorded either by fossil tracks and trails or remains of skeletons The observation that such fossils are absent in Precambrian strata proves that these phyla arose in the Cambrian |
As Chen and Zhou explain animals such as brachiopods and most echinoderms and mollusks cannot exist without a mineralized skeleton Arthropods bear jointed appendages and likewise require a hard organic or mineralized outer covering Therefore the existence of these organisms in the distant past should be recorded either by fossil tracks and trails or remains of skeletons The observation that such fossils are absent in Precambrian strata proves that these phyla arose in the Cambrian |
| Match 194 (1):
Reference (010331 .. 010358, of 28480): |
Subject (008012 .. 008039, of 22118): |
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Others have explained the absence of transitional organisms as the result of their putatively tiny size Some have even suggested that transitionals only existed in the larval stage |
Others have explained the absence of transitional organisms as the result of their putatively tiny size Some have even suggested that transitionals only existed in the larval stage |
| Match 195 (1):
Reference (010360 .. 010408, of 28480): |
Subject (008041 .. 008089, of 22118): |
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While possible perhaps it should be noted that cells of filamentous microorganisms interpreted as cyanobacteria have been discovered and documented in the Warrawoona Group strata of western Australia These microfossils found in bedded carbonaceous cherts are estimated to be between 3 3 billion to 3 5 billion years old |
While possible perhaps it should be noted that cells of filamentous microorganisms interpreted as cyanobacteria have been discovered and documented in the Warrawoona Group strata of Western Australia These microfossils found in bedded carbonaceous cherts are estimated to be between 3 3 billion to 3 5 billion years old |
| Match 196 (1):
Reference (010410 .. 010436, of 28480): |
Subject (008091 .. 008116, of 22118): |
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Species of single celled algae and the appearance of cells with a nucleus about 2 7 billion years ago have been well documented in the fossil record |
Species of single celled algae and the appearance of cells with a nucleus about 2 7 billionyears ago have been well documented in the fossil record |
| Match 197 (1):
Reference (010448 .. 010522, of 28480): |
Subject (008128 .. 008201, of 22118): |
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are far older and therefore far more rare due to the greater likelihood of tectonic destruction it would seem that the allegedly tiny fossil precursors of the Cambrian animals should have been found somewhere in the over 500 million years of sedimentary strata below the Cambrian Moreover as already noted the Precambrian rocks in China beneath the Chengjiang Cambrian biota reveal the presence of tiny sponge embryos at the very earliest stages of cell division |
are far older and therefore far rarer due to the greater likelihood of tectonic destruction it would seem that the allegedly tiny fossil precursors of the Cambrian animals should have been found somewhere in the over 500 million years of sedimentary strata below the Cambrian Moreover as already noted the Precambrian rocks in China beneath the Chengjiang biota clearly reveal the presence of tiny sponge embryos63 at the very earliest stages of cell division |
| Match 198 (1):
Reference (010541 .. 010551, of 28480): |
Subject (008219 .. 008228, of 22118): |
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any of the allegedly miniature or soft bodied ancestral forms of |
any of the allegedly miniature transitional or ancestral forms of |
| Match 199 (1):
Reference (010608 .. 010655, of 28480): |
Subject (008285 .. 008333, of 22118): |
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preservation unlikely do not help to account for the specific absence of Precambrian ancestral forms We know for example that nearshore sands do not favor preservation of detail let alone the fine detail of very small organisms a millimeter or less in length Similarly paleontologists rarely find the |
preservation unlikely in general do not help to account for the specific absence of Precambrian ancestral forms We know that near shore sands do not favor preservation of detail let alone the fine detail of very small organisms a millimeter or less in length Similarly paleontologists rarely find the |
| Match 200 (1):
Reference (010664 .. 010688, of 28480): |
Subject (008334 .. 008358, of 22118): |
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remains of parasites that live in the soft tissues of other organisms indeed parasitic organisms represent several of the phyla that have no fossil record |
remains of parasites that live in the soft tissues of other organisms indeed parasitic organisms represent several of the phyla that have no fossil record |
| Match 201 (1):
Reference (010690 .. 010825, of 28480): |
Subject (008360 .. 008496, of 22118): |
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Even so such considerations do little to bolster the artifact hypothesis The carbonates phosphorates and shales of the Precambrian strata beneath the Chengjiang fauna for example would have provided moderate to very favorable depositional environments in Precambrian times Yet these strata do not preserve plausible ancestral forms for any of the animals in the Cambrian beds of the Chengjiang Advocates of the artifact hypothesis need to show not just that certain factors discourage preservation in general which is not disputed but that these factors were ubiquitous in Precambrian depositional environments worldwide If nearshore sands characterized all Precambrian sedimentary deposits then paleontologists would not expect to find any ancestral or at least any tiny ancestral forms for the Cambrian animals Yet clearly this is not the case Precambrian strata include many types of sediments that can preserve |
Even so such considerations do little to bolster the artifact hypothesis The carbonates phosphorates and shales of the Precambrian strata beneath the Chengjiang fauna for example would have provided moderate to very favorable depositional environments in Precambrian times Yet these strata do not preserve plausible ancestral forms for any of the animals in the Cambrian beds of the Chengjiang Advocates of the artifact hypothesis need to show not just that certain factors discourage preservation in general which is not disputed but that these factors were ubiquitous in Precambrian depositional environments worldwide If near shore sands characterized all Precambrian sedimentary deposits then paleontologists would not expect to find any ancestral or at least any tiny ancestral forms for the Cambrian animals Yet clearly this is not the case Precambrian strata include many types of sediments that can preserve |
| Match 202 (1):
Reference (010834 .. 010843, of 28480): |
Subject (008496 .. 008505, of 22118): |
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preserved animal remains in fine detail Yet no forms plausibly |
preserve animal remains in fine detail Yet no forms plausibly |
| Match 203 (1):
Reference (010845 .. 010873, of 28480): |
Subject (008507 .. 008535, of 22118): |
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to the metazoan animals have been found in such beds The implausibility of the artifact hypotheses in its various manifestations has been reinforced by recent work in statistical paleontology |
to the metazoan animals have been found in such beds The implausibility of the artifact hypotheses in its various manifestations has been reinforced by r |