Stanford researchers show adaptation plays a significant role in human evolution

Jan 16, 2009

For years researchers have puzzled over whether adaptation plays a major role in human evolution or whether most changes are due to neutral, random selection of genes and traits.

Geneticists at Stanford now have laid this question to rest. Their results, scheduled to be published Jan. 16 online in Public Library of Science Genetics, show adaptation-the process by which organisms change to better fit their environment-is indeed a large part of human genomic evolution.

"Others have looked for the signal of widespread adaptation and couldn't find it. Now we've used a lot more data and did a lot of work cleaning it up," said Dmitri Petrov, associate professor of biology at Stanford University and one of two senior authors of the paper. "We were able to detect the adaptation signatures quite clearly, and they have the characteristic shape we anticipated."

All genetic mutations start out random, but those that are beneficial to an organism's success in their environment are directly selected for and quickly perpetuate throughout the population, providing a uniform, traceable signature.

With the help of post-doctoral researcher James Cai and recent graduate student Michael Macpherson, Petrov and co-senior author Guy Sella, a biologist at the Hebrew University of Jerusalem, used different methodology from what's been used before to look for signatures of adaptation left in the human genome.

"We detected a number of signatures that suggest adaptation is quite pervasive and common," Petrov said.

Humans have a very complex history from traveling around the globe, and the human genome is also highly structured, making it complicated and difficult to work with, he said.

To find the adaptation signal, Petrov and his colleagues looked for regions of the genome that "hitchhiked" along with an adaptation. When a genetic adaptation occurs and is passed on to offspring, other genes on both sides of the adaptation typically accompany it. The result is a whole region of the genome where all humans are unusually similar to each other, referred to as a "selective sweep," that researchers can identify and trace through human genetic history.

"Adaptation becomes widespread in the population very quickly," Petrov said. "Whereas neutral random mutation doesn't and would not have the selective sweep signature."

"We tried to see if these regions of unusual similarity among all humans tended to be in particular places in the genome as the theory predicts they should be, and indeed we find them there," Petrov said. "The work suggests human beings have undergone rampant adaptation to their environment in the last 200,000 years of history."

In the past, these sweeps were difficult to discern because the data were not sufficiently abundant and were filled with noise. Depending on the methodology, estimates of the degree of adaptation in humans ranged from as high as 30 percent down to zero. Signatures were impossible to interpret with confidence.

"People would find changes in specific genes suggesting that recent adaptations in humans might be common but could not find genome-wide signatures of pervasive adaptation. That was unsettling," Petrov said. "I'm hoping that people will react with relief that things are starting to make sense."

Petrov hopes that researchers can now do a much better job of finding the regions within the genome responsible for specific human adaptations and relate them to changes in human history or past environments. For example, one could trace the arrival of lactose tolerance to the domestication of cattle and the introduction of milk into our adult diet.

"As the data are going to grow, we should be able to locate specific adaptive events quite well," Petrov said. "By identifying specific genes, we can unravel this evolutionary history of adaptive change."

Another possibility is tracing the origin of skin pigmentation genes, which give people their different skin-color types. Many of these genes are linked to skin cancer. Researchers may be able to recreate past environments while better understanding how adaptation comes into play.

"We see signatures of possibly hundreds of recent adaptive events, and now we can ask what are they doing there," he said. "It's both exiting and puzzling."

This paper follows similar work in bacteria and fruit flies indicating adaptation is a significant contribution to evolution as a whole.

"We are on a crest of a wave showing that adaptation is a lot more prevalent than we thought," Petrov said.

Source: Stanford University

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Modernmystic
4 / 5 (2) Jan 16, 2009
Not to sound too arrogant here, but I always kind of considered this a no-brainer and always assumed it to be the case. I guess that you do have to prove the sky is blue to some people though. Good science is partly about covering ALL your bases I guess...no matter how obvious they seem to some.
HenisDov
not rated yet Feb 22, 2009
On Humans (And Other Materials) Evolution
And On The Sad State Of Life Sciences In 2009


Re "Stanford researchers show adaptation plays a significant role in human evolution"
http://www.eureka...1409.php


1) "For years researchers have puzzled over whether adaptation plays a major role in human evolution or whether most changes are due to neutral, random selection of genes and traits."

- I have been presenting evidence for years that adaptation, i.e. culture, is the driver of evolution of all life including human and, yes, of all other materials, and that genetic evolution is generally biased, not random.

2) "Geneticists at Stanford now...show adaptation, the process by which organisms change to better fit their environment, is indeed a large part of human genomic evolution."

- Shortly after retiring from industrial consulting (1956 - 1998) I started investigating the state of comprehension of the nature of life and of its evolution and I published evidence and conclusion that culture is the driver of all genomic evolution.

3) "Others have looked for the signal of widespread adaptation and couldn't find it...now...we were able to detect the adaptation signatures quite clearly"

- I found the evidence many years ago and presented it clearly in my postings.

4) "All genetic mutations start out random, but those that are beneficial to an organism's success in their environment are directly selected for and quickly perpetuate throughout the population, providing a uniform, traceable signature."

- NO NO NO. The drive of evolution is NOT RANDOM followed by survival selection. It is biased, as explained in my "Life's Manifest" and elaborated in my posts about the role of culture in evolution.

5) "Humans have a very complex history from traveling around the globe, and the human genome is also highly structured, making it complicated and difficult to work with, he said."

- The human genome, like all other genomes, is complicated, being a multi-genes organism, an organism that consists of a cooperative commune of the smaller Earth's primal organisms, namely of genes.

6)"Adaptation becomes widespread in the population very quickly," Petrov said. "Whereas neutral random mutation doesn't and would not have the selective sweep signature."

- Bravo. This happens to be a correct statement. Random mutations are mechanical accidents that the organism may or may not overcome to survive.


I stop here. No patience nor interest to continue picking at each of the following paras. Just sadly frustrated at The Sad State Of Life Sciences In 2009...


Respectfully yours,

Dov Henis
(Comments From The 22nd Century)
http://blog.360.y...Q--?cq=1

Life's Manifest
http://www.the-sc...page#578

EVOLUTION Beyond Darwin 200
http://www.physfo...ic=14988&st=405&#entry396201
http://www.the-sc...age#1407
HenisDov
not rated yet Jun 10, 2009
Evolution, Genetics And Culture
There is no Science except for the Establishment's alone, and Peer Approved is the Establishment's only apostle?


A. From "Adaptation and the evolution of parasite virulence in a connected world"

http://www.nature...071.html
Adaptation is conventionally regarded as occurring at the level of the individual organism, even if some posit the idea of adaptation at the group level.

This from Nature advance online publication 27 May 2009, Received 13 January 2009, Accepted 9 April 2009, Published online 27 May 2009. Nature is a member of the Science Guild Establishment, of course.


B. There is no Science except for the Establishment's alone, and Peer Approved is the Establishment's only apostle

The Science Guild Establishments, since its Mount Sinai Revelation as AAAS, has been prostituting all aspects of science, including the meanings of the terms science, scientists and research. It monopolized all terminology and publications of information, blocking insights and evolution of science. It turned the organization and activities of science into a ludicrous caricature of a corrupt trade union. This is the origin and explanation of the circa 100 years old black hole in science and of the zero effect of science on societal evolution during the still ongoing 20th century technology culture.


C. Culture, and, yes, intelligence, are ubiquitous traits of ALL matter, not just of life but including life

Adaptation is culture. And culture is the driver of Universal Evolution, of all evolutions.
"Rethink Unified Field Theory And Evolution"
http://www.the-sc...page#982

Animate and inanimate materials differ from each other in the capability of responding (intelligence) and in the mode and speed of responding (culture) to circumstances. These differences are due to the energetic constructs differences between animate and inanimate materials.


D. Yes, there is Science outside the Establishment's, and Peer Approved is not its only apostle,


Suggesting,

Dov Henis
(Comments From The 22nd Century)
Updated Life's Manifest May 2009
http://www.physfo...ic=14988]http://www.physfo...ic=14988[/url]&st=495&#entry412704
http://www.the-sc...age#2321
EVOLUTION Beyond Darwin 200
http://www.physfo...ic=14988]http://www.physfo...ic=14988[/url]&st=405&#entry396201
http://www.the-sc...age#1407
Ethelred
not rated yet Jun 17, 2009
but I always kind of considered this a no-brainer and always assumed it to be the case


It would be a no brainer except that a lot of computer simulations have come up with results that lean towards randomness rather than adaptation. The book I saw them in was not detailed enough to be sure but I always thought they had some highly questionable assumptions.

Basically if your theory doesn't fit the facts then its wrong. Those simulations looked to result in a different world than the one we live in. I just can't see random change alone as resulting new species or even ANY kind of adaptation.

Yes this a late reply. I stumbled on this while looking at HenisDov's profile. I am trying find out if he has actually interacted with anyone or if he is just spamming the site.

So far it looks like another case of someone CRANKING out spam.

Ethelred

QubitTamer

Quantum Physicist, torturer of AGW religious zealots like Ethelred because i laugh at his hysterics.