Tag Archives: John Hawks

How Fast Are Humans Evolving?

paleo diet, Steve Parker MD,calcium, osteoporosis

I’m guessing she’s northern European, perhaps Irish

Most paleo lifestyle proponents think that, genetically speaking, those of us living today are pretty much the same as our ancestors living 50,000 or even 200,000 thousand years ago. That may not be the case.

Conventional Wisdom

The traditional view of the rate of human evolution’s is articulated by Artemis P. Simopoulos, who was with The Center for Genetics, Nutrition and Health in 2009 when he wrote: “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.”

Evolving Thought

 

On the other hand, the experts are debating now whether the pace of human evolution has accelerated over the last 10,000 years. The iconoclasts say it has. For example, remember that most mammals lose the ability to digest milk after they’ve been weaned off the teat in early life: they lose the lactase enzyme that allowed them to digest milk sugar (lactose). That’s why lactose intolerance is so common among adult humans—only a third of us worldwide can digest milk. Five or 10,000 years ago, a genetic mutation occurred that allowed those possessing the gene to consume and digest milk. So a whole new source of food for adults opened up: dairy cattle. Would that have conferred a survival advantage? You bet. We have evidence that the milk-digesting mutation spread fairly quickly since its appearance. But it hasn’t spread across the globe uniformly. The ability to digest milk in adulthood—called lactase persistence—is less than 40% in Greece and Turkey, but higher than 90% in the UK and Scandinavia.

Another oft-cited example of rapid and recent human evolution is the appearance and spread of blue eyes starting six to 10,000 years ago. Everyone with blue eyes today apparently has a common ancestor that had a gene mutation back then, when everybody had brown eyes.

For more information on the “rapid evolution” idea, check out the writings of Gregory Cochran, Henry Harpending, and John Hawks. Also consider a new book by Nicholas Wade, “A Troublesome Inheritance: Genes, Race, and Human History.” Wade is a science writer for the New York Times.

Steve Parker, M.D.

John Hawks’ Perspective on the New Dmanisi Skull

…at his blog. A snippet:

What population structure characterized the African ancestors of the Dmanisi hominins? If we look to the MSA African model, the structure would be one of multiple populations, strongly differentiated, that had existed for hundreds of thousands of years. They may have had adaptations to local ecological conditions, but they were not isolated — they shared genes and one might occasionally replace another, only to re-differentiate as climate fluctuated. The African populations that existed at 1.8 million years ago were probably a modified subset of those that existed 2 million or 2.2 million years ago. Some of these populations would have been morphologically distinctive enough that paleontologists might call them different species. Some of the remixture between them would have been slight, on the scale of Neandertal mixture into today’s human populations. But those cases were at one end of a continuum that included larger amounts of genetic exchange and more rapid turnover. It was a braided stream, in which some of the rivulets were long, but others were short.

Read the rest and you’ll find a brief review of early human evolution.

That Explains a Lot: Our Brains Are Shrinking

…and nobody knows why although there’s no shortage of conjecture. From an article at Discovery magazine:

 

John Hawks is in the middle of explaining his research on human evolution when he drops a bombshell. Running down a list of changes that have occurred in our skeleton and skull since the Stone Age, the University of Wisconsin anthropologist nonchalantly adds, “And it’s also clear the brain has been shrinking.”

 

“Shrinking?” I ask. “I thought it was getting larger.” The whole ascent-of-man thing.

 

“That was true for 2 million years of our evolution,” Hawks says. “But there has been a reversal.”

Read more.

 

Free Online Paleoanthropology “Textbook”: John Hawks Blog

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:

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.

Steve Parker, M.D.

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.