I’ve never seriously studied anthropology, paleontology, or paleoanthropology. When I read someone who seems or claims to be an expert on paleoanthropology or certain aspects of evolution, it requires a degree of trust on my part.
(I have a stronger background in evolution, thanks to a B.S. degree in Zoology. I was thoroughly indoctrinated in the mid-1970s.)
It was a slow day at work, so I just spent a couple hours perusing the blog of an actual paleoanthropologist named John Hawks. It’s a massive database that may be the equivalent of a paleoanthropology textbook. Naturally, it will reflect the biases of the author, if any (and we all have some, don’t we?) .
Some interesting things you’ll find there:
- the iconoclastic thought that human evolution has accelerated over the last five or ten thousand years, thanks to our population growth
- we don’t know as much as you may think we do about ancestral diets and lifestyles; researchers may over-interpret the evidence
- explanations of modern investigative techniques
Regarding the pace of human evolution in the Neolithic period, Artemis P. Simopoulos (with The Center for Genetics, Nutrition and Health in 2009) has a different view:
The spontaneous mutation rate for nuclear DNA is estimated at 0.5% per million years. Therefore, over the past 10,000 years there has been time for very little change in our genes, perhaps 0.005%. In fact, our genes today are very similar to the genes of our ancestors during the Paleolithic period 40,000 years ago, at which time our genetic profile was established.
I dunno; you decide.
Reference: Simopoulos, Artemis P. Evolutionary aspects of the dietary omega-6:omega-3 fatty acid ratio: medical implications. World Review of Nutrition and Dietetics, 100 (2009): 1-21. Epub August 17, 2009.
I was talking about this issue with Stephan Guyenet and Mat Lalonde last Saturday – of course we have made some adaptations to neolithic foods and agriculture, and the amount of genetic change will depend on selection pressure (for lactose tolerance in adulthood – quite high, for increased folate absoprtion/metabolism in a low-folate population, quite high, and there is also hemochromatosis, where a high-iron, paleolithic diet would be disastrous, and phytic acid is the best thing, along with blood loss!)
In addition, we have epigenetic changes, which can happen relatively quickly and vastly change phenotype, though I think it is unclear how much these changes are reflected over generations.
It is fascinating – and complex!
I was thinking about selection pressure as I wrote the original post. Black Death (probably caused by Yersinia pestis) killed about 45% of Europe’s population in the 14th century. And European colonization of the New World devastated native populations.
That’s heavy selection pressure.
On the other hand, modern medicine and surgery, better nutrition, sewage systems, water purification, and other technologies greatly mitigate selection pressure.
I’ll have to re-read Hawks’ thoughts on accelerated human evolution. It seems to hinge on greater rates of reproduction leading to more genetic variation.
very silly for that guy to extrapolate evolutionary change from some across the board mutation rate. don’t even know where to start with that.
if you’re interested in the recent acceleration of human evolution, the obvious text is cochran and harpending’s 10,000 year explosion. they’ve just started a blog http://westhunt.wordpress.com/. the evidence for this hypothesis is strong and the resistance to it is political.
Jay, thanks for the comments. Reading Hawks, I found he assumes his readers know what “SNP” means. I don’t.