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  Topic: Darwin, Right and Wrong, Listing the points< Next Oldest | Next Newest >  
Wesley R. Elsberry



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Joined: May 2002

(Permalink) Posted: Feb. 07 2006,10:28   

Over on PT, it was mentioned that Darwin was wrong about some things. In my experience, people who say that often have little clue about what Darwin even did say, much less having any detailed notion of what he might have been wrong about. So I decided that this would be a good place to expand on what Darwin said, and whether it has held up over the years or not. Therefore, not just the things that he got wrong, but also the things that he got right.

Here's my lead-in:

Quote

Yeah, sure, let's list the things Darwin was right and wrong about. I'll spot you guys two items in each category. Right: mechanism of coral atoll formation and importance of earthworms in agricultural soil maintenance. Wrong: Pangenesis and natural selection being the <b>main</b> mechanism of evolutionary change.


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"You can't teach an old dogma new tricks." - Dorothy Parker

    
Russell



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(Permalink) Posted: Feb. 07 2006,10:45   

OK. I'm going to flaunt my ignorance. What's "pangenesis", and what is the "main" mechanism of evolutionary change?

But just to contribute something, Darwin was wrong on human male/female mental characteristics.

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Must... not... scratch... mosquito bite.

  
BWE



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(Permalink) Posted: Feb. 07 2006,10:52   

Darwin was wrong when he claimed (without proof) that jesus never lived and that god had no part to play in the creation of man. How bout that?

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Who said that ev'ry wish would be heard and answered
When wished on the morning star
Somebody thought of that, and someone believed it
Look what it's done so far

The Daily Wingnut

   
C.J.O'Brien



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(Permalink) Posted: Feb. 07 2006,11:28   

Re: the "main" mechanism.

Huh? Natural Selection is the only mechanism, in principle, that can explain the adaptive complexity we see in nature. Now, "adaptive complexity" is not the end of "evolutionary change," so maybe we're talking about drift, the founder effect, and other elements of speciation. But it's the "purposeful arrangement of parts," to use Beheian terminology, that gets everyone talking, and that really demands an explanation.

So maybe you can clarify for me, Wesley.

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Dean Morrison



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(Permalink) Posted: Feb. 07 2006,17:44   

Without actually being wrong as such Darwin had a gap in his theory until Mendel came along. 'Blending' of characteristics at each generation would have not have given 'Natural Selection' anything to get it's teeth into. The combination of the two into 'neo-Darwinism' gives the complete theory.

Were you being confrontational about the 'Natural Selection' thing Wesley? or were you going to make a point about sexual selection or something?

  
Wesley R. Elsberry



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(Permalink) Posted: Feb. 07 2006,17:49   

Pangenesis was Darwin's proposed mechanism of inheritance. He proposed the existence of tiny "pangenes" or "gemmules" which would carry information about somatic cells to germ cells, where somehow this information would be incorporated into the gametes. This would have permitted the sort of Lamarckian inheritance that Darwin thought was correct, allowing for "use and disuse" to influence traits in succeeding generations. See Darwin's The Variation of Animals and Plants Under Domestication for the original explication of the hypothesis.

The mode of evolution is neutral evolution. In the 1960s, gel electrophoresis results showed widespread "protein polymorphism" -- and lots of it. As the technology has gotten better, scientists have examined genetic sequences, and the amount of variation seen there indicates that many times more change is due to neutral evolution than to natural selection. I asked Richard Dawkins about this via calling in to a radio talk show he was on in the fall of 2004, and he said that when one looks at the molecular level, most of what one sees is neutral change, but that at the level of observable morphological traits, most of those are due to natural selection. Darwin said otherwise in his introduction to the Origin of Species: Furthermore, I am convinced that Natural Selection has been the main but not exclusive means of modification.

Quote

Darwin was wrong when he claimed (without proof) that jesus never lived and that god had no part to play in the creation of man. How bout that?


It'll be cool when we get some citations to where Darwin said that. I've put up references in what I discussed above; now it is your turn.

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"You can't teach an old dogma new tricks." - Dorothy Parker

    
Russell



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(Permalink) Posted: Feb. 08 2006,03:49   

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[Dawkins] said that when one looks at the molecular level, most of what one sees is neutral change, but that at the level of observable morphological traits, most of those are due to natural selection. Darwin said otherwise in his introduction to the Origin of Species: Furthermore, I am convinced that Natural Selection has been the main but not exclusive means of modification.
In my mind, this turns out to be something of a semantic question. Obviously, Darwin wasn't opining about changes in nucleic acid sequences; he was looking at observable differences, and in that area I'm not so sure natural selection doesn't still reign supreme.

(Btw, surely the comment about Darwin and Jesus was a joke, no?)

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Must... not... scratch... mosquito bite.

  
Wesley R. Elsberry



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(Permalink) Posted: Feb. 08 2006,08:49   

Quote

In my mind, this turns out to be something of a semantic question. Obviously, Darwin wasn't opining about changes in nucleic acid sequences; he was looking at observable differences, and in that area I'm not so sure natural selection doesn't still reign supreme.


Dawkins's answer to the question echoes that sentiment. Nevertheless, the fact is that natural selection does not account for most evolutionary change.

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"You can't teach an old dogma new tricks." - Dorothy Parker

    
jeannot



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(Permalink) Posted: Feb. 08 2006,11:44   

Quote (Wesley R. Elsberry @ Feb. 08 2006,14:49)
Quote

In my mind, this turns out to be something of a semantic question. Obviously, Darwin wasn't opining about changes in nucleic acid sequences; he was looking at observable differences, and in that area I'm not so sure natural selection doesn't still reign supreme.


Dawkins's answer to the question echoes that sentiment. Nevertheless, the fact is that natural selection does not account for most evolutionary change.

... at the molecular level.
This is the neutral theory of Motoo Kimura, indeed.
It is my opinion, but substitutions of billions of non-coding nucleotides don't represent any "evolutionary change". They don't have any impact on the phenotype.

  
Wesley R. Elsberry



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(Permalink) Posted: Feb. 08 2006,12:25   

Who said that they are all non-coding? Neutral is not synonymous with "silent".

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"You can't teach an old dogma new tricks." - Dorothy Parker

    
sir_toejam



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(Permalink) Posted: Feb. 08 2006,12:48   

Quote
Nevertheless, the fact is that natural selection does not account for most evolutionary change.


i disagree that you can quantify this in such a fashion, even taking a horribly small subset of traits and characteristics in order to formulate a hypothesis.

there are simply too many traits and too many variable mutation/selection agents to make the relative contributions on a large scale meaningful.

in one population, you might see neutral mutations as being the dominant force driving phenotypic changes over time, while in another, selective forces could be quite different, and far more important.

How many natural populations can you cite where ALL selective pressures have been quantified over time, and compared to the effects of neutral mutation?

fancy trick, that.

perhaps you are leading up to the models suggesting that selection acts as a primary evolutionary force only in small, isolated populations?

  
jeannot



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(Permalink) Posted: Feb. 09 2006,12:06   

Quote (Wesley R. Elsberry @ Feb. 08 2006,18:25)
Who said that they are all non-coding? Neutral is not synonymous with "silent".

You're right. "Neutral" doesn't refer to mutations that have no effect on phenotype (silent), it refers to mutations that don't affect fitness.
However, as toejam has just pointed out, I don't think we can assert that most phenotypic changes do not affect the fitness of individuals.
And we would have to assign some relative weight to the “evolutionary changes” we measure. Should we consider a mutation in the junk DNA as important as a mutation in a hox gene, which could cause a major morphological change?

  
Dean Morrison



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(Permalink) Posted: Feb. 12 2006,01:24   

'Neutral evolution' seems a bit pedantic to me - a bit like saying that the main change in Wesley R. Elsberry since he started this board is that his water molecules have been exchanged for different water molecules (including some with a different atomic mass) - rather than that he has got a bit older.

Technically correct to say this the 'main' form of change - but in terms of importance in any other sense? - perhaps not.

  
jeannot



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(Permalink) Posted: Feb. 12 2006,03:31   

Quote (Dean Morrison @ Feb. 12 2006,07:24)
'Neutral evolution' seems a bit pedantic to me - a bit like saying that the main change in Wesley R. Elsberry since he started this board is that his water molecules have been exchanged for different water molecules (including some with a different atomic mass) - rather than that he has got a bit older.

Technically correct to say this the 'main' form of change - but in terms of importance in any other sense? - perhaps not.

That is a fair remark Dean, but we are talking about "evolutionary changes", changes that can be inherited.
Metabolism, maturation, growth, phenotypic plasticity... don't belong to this category.

  
Dean Morrison



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Joined: Dec. 2005

(Permalink) Posted: Feb. 12 2006,10:51   

The use of the word 'main' in this sense suggests a 'value statement.

If by 'main' you mean:

quantification of base pair changes over time -

but why chose this measure over:

'base pair changes having phenotypic consequences' - or:

'base pair changes resulting in phenotypic consequences susceptible to selection. ( I realise this latter may result in a circular definition).

- we can agree what is happening - but I think the use of the word 'main' is value laden here

  
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