This google news query should get you to popular press articles. I’ll start putting links to blogs when more come in.
Blogs: One of the lead authors, John Hawks, promises lots of commentary this week. Greg Laden has some questions regarding the demographic assumptions. Steve Sailer with a round-up and Linda Seebach offers the bigger picture. p-ter offers some pointed criticisms. John Hawks does some rapid response. Eric Wang and Henry Harpending offer specific comments. John Hawks’ summary for lay people (long). Shoshin goes over the theory too. Popgen Ramblings says simulation is important. p-ter offers more “notes.” Popgen Ramblings has another post up in response to a John Hawks comment..
Quotes below from news articles….
More people mean more mutations, Harpending noted.
“You are also giving them the potential to be adaptive mutations,” said Brian Verrelli, who studies population genetics and evolution at Arizona State University in Tempe and was not involved in the research.
Verrelli said the new study is interesting and accurately explains the accelerated evolution with a plausible model based on demographics.
Importantly, he said, the research indicates that any speed-up in evolution “had to have happened differently in different geographic regions.”
“Ten thousand years ago, as men switched to an agricultural lifestyle, their bodies began getting smaller, and along with their bodies, their brains also decreased in size,” anthropologist John Hawks told Haaretz. Hawks, who headed the team of researchers at Wisconsin, said nutritional changes constituted one of the reasons – but not the only one – behind the reduction in body size.
“Man himself has changed and become smaller,” Hawks said. At the same time, the average height in the West began to grow during the past two hundred years. However, Hawks attributes that to better nutrition, rather than to genetic changes
The brisk rate of human selection occurred for two reasons, Dr. Moyzis’ team says. One was that the population started to grow, first in Africa and then in the rest of the world after the first modern humans left Africa. The larger size of the population meant that there were more mutations for natural selection to work on. The second reason for the accelerated evolution was that the expanding human populations in Africa and Eurasia were encountering climates and diseases to which they had to adapt genetically. The extra mutations in their growing populations allowed them to do so.
David Reich, a population geneticist at the Harvard Medical School, said the new report was “a very interesting and exciting hypothesis” but that the authors had not ruled out other explanations of the data. The power of their test for selected genes falls off in looking both at more ancient and more recent events, he said, so the overall picture might not be correct.
Similar reservations were expressed by Jonathan Pritchard, a population geneticist at the University of Chicago.
“My feeling is that they haven’t been cautious enough,” he said. “This paper will probably stimulate others to study this question.”
“In evolutionary terms, cultures that grow slowly are at a disadvantage, but the massive growth of human populations has led to far more genetic mutations,” says Hawks. “And every mutation that is advantageous to people has a chance of being selected and driven toward fixation. What we are catching is an exceptional time.”
“Ten thousand years ago, no one on planet Earth had blue eyes,” Hawks notes, because that gene–OCA2–had not yet developed. “We are different from people who lived only 400 generations ago in ways that are very obvious; that you can see with your eyes.”
Richard Potts, director of the human origins program at the Smithsonian Institution’s National Museum of Natural History, said he thinks the researchers reasoning regarding rapid adaptive change is plausible.
The study mainly points to an overall expansion in the human population over the past 40,000 years to explain the genetic data.
“Yet the archaeological record also shows that humans increasingly divided themselves into distinct cultures and migrating groups — factors that seem to play only a small role in their analysis. Dividing the human population into finer units and their movement into new regions — the Arctic, Oceania, tropical forests, just to name some — may have also forced quicker adaptive evolution in our species,” Potts said.
Harpending said the genetic evidence shows that people worldwide have been getting less similar rather than more similar due to the relatively recent genetic changes.
Genes have evolved relatively quickly in Africa, Asia and Europe but almost all of the changes have been unique to their corner of the world. This is the case, he said, because since humans dispersed from Africa to other parts of the world about 40,000 years ago, there has not been much flow of genes between the regions.
In the study, researchers analzyed genomes from 270 people belonging to four disparate ethnic groups: Han Chinese, Africa’s Yoruba tribe, Japanese and Utah Mormons. By comparing areas of difference and similarity, they determined that about seven percent of the genome has undergone significant change since the end of the last Ice Age. “
Armand Leroi, Reader in Evolutionary Biology at Imperial College, London, said: “In principle, this could have led to speciation if it had continued. In practice, it has got to be the case that that cannot happen now. The reason is that this study has looked at largely separated populations in the past, but everything about human history since the Industrial Revolution weighs overwhelmingly against separation and thus against speciation too. Huge increases in gene flow are going to wipe this trend out.”
“We aren’t the same as people even 1,000 or 2,000 years ago,” he told the journal Proceedings of the National Academy of Sciences.
“The dogma has been these are cultural fluctuations, but almost any temperament trait you look at is under strong genetic influence.
“Human races are evolving away from each other. Genes are evolving fast in Europe, Asia and Africa, but almost all of these are unique to their continent of origin.
Our Stone Age ancestors were more genetically similar to Neanderthals than they are to us, as our species has evolved 100 times faster in the past 5,000 years than at any other time in human evolution, a new study indicates.
The findings are persuasive to anthropologist Clark Larsen of Ohio State University in Columbus. But not everyone is on board. “I don’t deny recent rapid selection,” says geneticist Kenneth Kidd of Yale University. “But I am not yet convinced that so much rapid selection at so many places in the genome has occurred. … I think we need much more data.”
Among the fastest-evolving genes are those related to brain development, but the researchers aren’t sure what made them so desirable, Hawks said.
There are other mysteries too.
“Nobody 10,000 years ago had blue eyes,” Hawks said. “Why is it that blue-eyed people had a 5% advantage in reproducing compared to non-blue-eyed people? I have no idea.”