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  Topic: Study Detects Recent Instance of Human Evolution, NY Times Story< Next Oldest | Next Newest >  
stevestory



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Joined: Oct. 2005

(Permalink) Posted: Dec. 10 2006,23:56   

Quote
A research team led by Sarah Tishkoff of the University of Maryland has now resolved much of the puzzle. After testing for lactose tolerance and genetic makeup among 43 ethnic groups of East Africa, she and her colleagues have found three new mutations, all independent of each other and of the European mutation, which keep the lactase gene permanently switched on.

The principal mutation, found among Nilo-Saharan-speaking ethnic groups of Kenya and Tanzania, arose 2,700 to 6,800 years ago, according to genetic estimates, Dr. Tishkoff’s group is to report in the journal Nature Genetics on Monday. This fits well with archaeological evidence suggesting that pastoral peoples from the north reached northern Kenya about 4,500 years ago and southern Kenya and Tanzania 3,300 years ago.

Two other mutations were found, among the Beja people of northeastern Sudan and tribes of the same language family, Afro-Asiatic, in northern Kenya.

Genetic evidence shows that the mutations conferred an enormous selective advantage on their owners, enabling them to leave almost 10 times as many descendants as people without them. The mutations have created “one of the strongest genetic signatures of natural selection yet reported in humans,” the researchers write.


http://www.nytimes.com/2006....=slogin

   
ericmurphy



Posts: 2460
Joined: Oct. 2005

(Permalink) Posted: Dec. 11 2006,14:35   

But if humans evolved from humans, why are there still humans?

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2006 MVD award for most dogged defense of scientific sanity

"Atheism is a religion the same way NOT collecting stamps is a hobby." —Scott Adams

  
Occam's Aftershave



Posts: 1773
Joined: Feb. 2006

(Permalink) Posted: Dec. 11 2006,15:08   

Thanks SteveS, that's good stuff.  Yet another real world example of a beneficial mutation to rub the in the faces of AFDave Cretos everywhere.

Here is a link to the original article (abstract only unless you pay) in Nature Genetics

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"Science is what got us to the humble place we’re at, and what hard-won progress we might realize comes from science, with ID completely flaccid, religious apologetics bitching from the sidelines." - Eigenstate at UD

  
skeptic



Posts: 1163
Joined: May 2006

(Permalink) Posted: Dec. 11 2006,15:27   

I had a question for Deadman (or anyone else in the field) concerning this research.  Are they tying the mutations of the dutch and swedes to these groups and if so how does that affect the current migration theory, if at all?  Or is this a case of convergent evolution in not only the European and African groups but also among the Eastern African groups or is there any way to tell at this time?

  
Russell



Posts: 1082
Joined: April 2005

(Permalink) Posted: Dec. 11 2006,15:34   

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I had a question ...  Are they tying the mutations of the dutch and swedes to these groups and if so how does that affect the current migration theory, if at all?
This didn't answer your question?
Quote
After testing for lactose tolerance and genetic makeup among 43 ethnic groups of East Africa, she and her colleagues have found three new mutations, all independent of each other and of the European mutation


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

  
Steviepinhead



Posts: 532
Joined: Jan. 2006

(Permalink) Posted: Dec. 11 2006,15:46   

Quote from article:
Quote
Almost all Dutch people and 99 percent of Swedes are lactose-tolerant, but the mutation becomes progressively less common in Europeans who live at increasing distance from the ancient Funnel Beaker region.

Geneticists wondered if the lactose tolerance mutation in Europeans, first identified in 2002, had arisen among pastoral peoples elsewhere. But it seemed to be largely absent from Africa, even though pastoral peoples there generally have some degree of tolerance.

A research team led by Sarah Tishkoff of the University of Maryland has now resolved much of the puzzle. After testing for lactose tolerance and genetic makeup among 43 ethnic groups of East Africa, she and her colleagues have found three new mutations, all independent of each other and of the European mutation, which keep the lactase gene permanently switched on.

Skeptic:
Quote
Are they tying the mutations of the dutch and swedes to these groups and if so how does that affect the current migration theory, if at all?  Or is this a case of convergent evolution in not only the European and African groups but also among the Eastern African groups or is there any way to tell at this time?


Skeptic, unless I'm misunderstanding your question, all the answers are in the NYT article.  Follow the link.  Read.  

Three new mutations, independent of each other and of the European one (Dutch, Swedes).  So, yes, they're "convergent," in the sense that different mutations have arisen in at least four populations to take advantage of the availability of milk from domesticated animals throughout life.

Since all these domestication events have occurred within the last few thousand years--and since the mutations are independent = not the same mutation, then this research has no impact on theories regarding migrations of modern humans out of Africa (if that's what you're talking about).  None of the mutations is a result of one population migrating to somewhere else (because they're different, independent mutations) and, in any event, all the domestication events were more recent than the posited out-migration and, obviously, all the mutations were even more recent.

  
ericmurphy



Posts: 2460
Joined: Oct. 2005

(Permalink) Posted: Dec. 11 2006,18:18   

Given that these are all "independent," i.e., "not the same mutation," and given how recently they all happened, i.e., over a relatively short period of time, this should give Dave some some reason to reconsider his claim that "beneficial" mutations are rare to the point of non-existence.

But it won't.

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2006 MVD award for most dogged defense of scientific sanity

"Atheism is a religion the same way NOT collecting stamps is a hobby." —Scott Adams

  
skeptic



Posts: 1163
Joined: May 2006

(Permalink) Posted: Dec. 11 2006,18:40   

my apologies Stevie, at first I thought you must have read a different article than I but after rereading I see that I just fuzzed out this morning.  Fighting a cold right now and that cold and flu medicine threw me for a loop.  Thanks for righting me.

  
Steviepinhead



Posts: 532
Joined: Jan. 2006

(Permalink) Posted: Dec. 11 2006,19:30   

Man, I wish I got the kind of colds that came with that kind of medication.

 :p  :p  :p

  
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