There is a lot of buzz about the recent (but still unavailable [update: link]) PNAS paper by John Hawks et al. reporting an accelerated rate of natural selection in humans. This time, I am not going to pick on the media who, predictably, are selling this as a conclusive finding when those of us in the scientific community have not even had a chance to read the paper yet, let alone for anyone to try to critically assess it. It may be fantastic work, and if it holds up I will certainly give it a significant place in my lecture on human evolutionary history. My complaint is about what the authors themselves have been telling the press.
“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.”
Interesting idea. But I suppose at no time in history could there have been another variant that caused blue eyes? Is this really the sort of thing that can only evolve once and in one way?
“We aren’t the same as people even 1,000 or 2,000 years ago,” he says, which may explain, for example, part of the difference between Viking invaders and their peaceful Swedish descendants.
Um, ok. I wonder if blue eyes make you peaceful?
Harpending says genetic differences among different human populations “cannot be used to justify discrimination. Rights in the Constitution aren’t predicated on utter equality. People have rights and should have opportunities whatever their group.”
And, by implication, the groups are not utterly equal. Care to speculate on which groups are more equal than which others?
The new study comes from two of the same University of Utah scientists – Harpending and Cochran – who created a stir in 2005 when they published a study arguing that above-average intelligence in Ashkenazi Jews – those of northern European heritage – resulted from natural selection in medieval Europe, where they were pressured into jobs as financiers, traders, managers and tax collectors. Those who were smarter succeeded, grew wealthy and had bigger families to pass on their genes. Yet that intelligence also is linked to genetic diseases such as Tay-Sachs and Gaucher in Jews.
“History looks more and more like a science fiction novel in which mutants repeatedly arose and displaced normal humans – sometimes quietly, by surviving starvation and disease better, sometimes as a conquering horde. And we are those mutants.”
Michael Crichton’s latest: LACTASE, the harrowing story of a small mutation that conferred a slightly better ability to digest milk and reached a higher frequency in some human populations. Expect the movie in summer 2010.
“Five thousand years is such a small sliver of time – it’s 100 to 200 generations ago,” he says. “That’s how long it’s been since some of these genes originated, and today they are in 30 or 40 percent of people because they’ve had such an advantage. It’s like ‘invasion of the body snatchers.’”
Genes, alleles. Tomayto, tomahto. Either way, they’re out to take us over!
“We are always trying to outrun disease.”
And body snatchers.
“Natural selection cares about how many children you have. People will have kids younger and younger.”
Where’s Bart Simpson when you need him? Natural selection is not conscious. Natural selection is not conscious. Natural selection is not conscious. Natural selection is n…
“Genetic engineering will make all this irrelevant. If people want green-haired kids they will go to the doctor and get them in 100 years.”
No they won’t, because people will be marrying robots by then.
“We are more different genetically from people living 5,000 years ago than they were different from Neanderthals.”
MNSdfnklcn. Oops, sorry… that was Coke sprayed all over my keyboard.
“In the last 40,000 years humans have changed as much as they did in the previous 2 million years.”
Nxjbjbecbc. Dammit… again!
“We found very many human genes undergoing selection,” says anthropologist Gregory Cochran of the University of Utah, a member of the team that analyzed the 3.9 million genes showing the most variation. “Most are very recent, so much so that the rate of human evolution over the past few thousand years is far greater than it has been over the past few million years.” [emphasis added]
Really? A few million years ago there were no humans at all.