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Science/Tech See other Science/Tech Articles Title: Human Evolution is Still Continuing This Thursday, February 12, 2009, marks the 200th anniversary of the birth of Charles Darwin, author of the 1859 book On the Origin of Species by Means of Natural Selection: Or The Preservation of Favoured Races in the Struggle for Life. (I guess Darwin didn’t get the memo about race not existing. You’ll see vast heapings of praise in the press for Darwin this week. Keep in mind, though, that if he were alive today, the same people now lauding the dead Darwin would be denouncing the living one the same way they demonized James Watson in 2007.) I’m pleased that a new book, The 10,000 Year Explosion: How Civilization Accelerated Human Evolution, demonstrates that Darwin has two worthy 21st Century successors of comparable insight and ambition: co-authors Gregory Cochran and Henry Harpending. (They’ve set up an official website for The 10,000 Year Explosion here). On a rather less epochal note, the publication of The 10,000 Year Explosion marks the tenth anniversary of my invitation-only Human Biodiversity email group, which I started in 1999. And that’s where Greg and Henry got to know each other! Peter Brimelow recently called to my attention that the inscription on the Westminster Abbey tomb of concert impresario J.P. Salomon reads, "He brought Haydn to England …" Perhaps my gravestone will read, "He introduced Cochran to Harpending." Henry Harpending, a professor at the University of Utah and member of the National Academy of Sciences, is one of the few field anthropologists (he lived for 42 months with hunter-gatherer peoples in Africa, such as the tongue-clicking Bushmen) with the mathematical skills to grapple with the current deluge of genetic data. (Here’s Henry’s hair-raising tale of going hunting with Bushmen for the most lethal African game animal, the Cape buffalo.) Greg Cochran, a physicist turned evolutionary theorist, is a polymath who might be the most ferociously brilliant idea man of his generation in America. Obviously, I’m biased about their The 10,000 Year Explosion. Over the last decade, I’ve spent perhaps a thousand hours talking to Greg Cochran on the phone. Or, to be more accurate, listening to Greg, which is how I’ve gotten a sizable fraction of my best ideas. (My worst ideas are all mine.) Cochran the conversationalist is at his acerbic best in a five part interview on the 2Blowhards blog: Day 1, Day 2, Day 3, Day 4, and Day 5. On the first page of The 10,000 Year Explosion, Cochran and Harpending quote the reigning conventional wisdom about humanity: "There’s been no biological change in humans in 40,000 or 50,000 years. Everything we call culture and civilization we’ve built with the same body and brain."— Stephen Jay Gould The co-authors then announce that they will undermine this standard presumption: "We intend to make the case that human evolution has accelerated in the past 10,000 years, rather than slowing or stopping, and is now happening about 100 times faster than its long-term average over the 6 million years of our existence. The pace has been so rapid that humans have changed significantly in body and mind over recorded history. Sargon and Imhotep were different from you genetically as well as culturally." As Greg quips, "The past may never be the same again." While Cochran and Harpending don’t have much respect for Gould, their book serves to complement the much-touted Jared Diamond’s 1997 bestseller Guns, Germs, and Steel, showing you what Diamond left out in his successful bid for political correctness. So, what happened 10,000 years ago? Agriculture. Farming changed everything. Planting crops and raising livestock allowed the human population to grow enormously. Cochran and Harpending note: "In Guns, Germs, and Steel, Jared Diamond observed: 'A larger area or population means more potential inventors, more competing societies, more innovations available to adopt—and more pressure to adopt and retain innovations, because societies failing to do well will be eliminated by competing societies.' We take this idea a step further: There are also more genetic innovations in that larger population." A hundred-fold growth in world population from its pre-agriculture size to the 60 million alive during the Bronze Age 3,000 years ago meant a similar hundred-fold increase in the rate of genetic mutations. Most random changes in DNA are deleterious and eventually die out. But favorable mutations, which improve the odds of survival and reproduction, are more likely to thrive and spread. Cochran and Harpending make the crucial mathematical point that a large population size increases the rate of favorable mutations much faster than it slows their dispersion: "One might think that it would take much longer for a favorable mutation to spread through such a large population than it would for one to spread through a population as small as the one that existed in the Old Stone Age. But … it takes only twice as long to spread through a population of 100 million as it does to spread through a population of 10,000. " Moreover, agriculture dramatically changed the environment that selects which mutations turn out to be favorable. To flourish, farmers have to be harder-working than hunter-gatherers, more orderly in densely crowded locations, less susceptible to alcoholism, and more foresighted (farmers can’t eat the seed corn). Harpending writes of his Bushmen friends: "They weren’t very good at self-denial back in the early Neolithic period, and they aren’t very good at it even today: Efforts to teach Bushmen to become herders frequently fail when they eat all their goats." Different cultures bring about different genes. Therefore, different kinds of agriculture select for different genes. For example, the "female farming" cultures of tropical Africa, where women do most of the work, tend to evolve different personalities on average than the labor-intensive rice-growing cultures of Northeast Asia. As I wrote in my 1997 review of Guns, Germs, and Steel: "Diamond makes environmental differences [between continents] seem so compelling that it's hard to believe that humans would not become somewhat adapted to their homelands through natural selection." Conversely, different genes bring about different cultures, at least in the short run. The authors illustrate their theories with countless historical and prehistorical examples, such as the beautiful but isolated village in Italy where 43 people possess a mutation from the late 18th century that protects against heart disease so well that it has increased their overall fitness by 7 percent. Going back further in time, a mutation for lactose-tolerance among adults emerged about 8,000 years ago and has since spread across a vast swath of western Eurasia and northern Africa, reaching 95 percent levels in southern Scandinavia. Lactose tolerance dramatically increased the Darwinian fitness of people living in grasslands because keeping cows for milk rather than just for meat produces five times the calories. Cochran and Harpending theorize that this lactose tolerance mutation accounts for the remarkable spread of Indo-European languages from Calcutta to Cork. "If this picture is correct, the occurrence of a single mutation in a particular group of pastoralists some 8,000 years ago eventually determined the spoken language of half of mankind." The 10,000 Year Explosion outlines a new type of scholarship: "genetic history," in which DNA differences between groups can drive major events. For example, the astonishing conquests of the great empires of Mexico and Peru by a few hundred Spaniards can be explained by immune system disparities between Old Worlders, who had been evolving in a stew of Afro-Eurasian infectious diseases, and New Worlders, whose ancestors hadn’t brought many germs with them when they crossed from Siberia to Alaska. Most controversially, Cochran and Harpending make a strong case that the high average IQs seen today among Ashkenazi (Central European) Jews are the results of Darwinian selection for mental skills useful in the finance-related jobs held by so many medieval Ashkenazi. I summarized this audacious theory in VDARE.com back in 2005, but their new write-up is the best version yet. The 10,000 Year Explosion features enough original ideas to launch a hundred Ph.D. dissertations. What proportion of their suggestions will turn out to be right, I don’t know. They’re founding a new branch of knowledge, so it will take decades to find out. Despite this density of novel notions, the book is remarkably readable. It’s much smoother sailing than On the Origin of Species. In fact, The 10,000 Year Explosion scores on the Microsoft Word readability scales as easier to read than my review of it. (One of the "deleted scenes" featured on the book’s website rings up a Flesch Reading Ease score of 45.1 and a Flesch-Kincade Grade Level of 12.5—not bad for a breakthrough book.) The writing style is a combination of casual and pithy, with a joke every couple of pages. Still, you can’t just breeze through this book. I found myself cruising along muttering, "Oh, yeah, that makes sense, I get it, yeah, I get that too, no problem, I get it, I get it, I …I … I … Wait a minute, where’d that idea come from?" And then I have to backtrack and think it over. A century and a half ago, Darwin penned two gnomic but prophetic sentences that didn’t blossom into the new field of evolutionary psychology until the late 20th century: "In the distant future I see open fields for far more important researches. Psychology will be based on a new foundation, that of the necessary acquirement of each mental power and capacity by gradation." Just as scientists still reread Darwin today to get new insights, they will be rereading Cochran and Harpending for decades to come.
Poster Comment: Turtle has known since he was 12 that evolution is ongoing. Turtle, after all, belongs to a new species, Turteus Brainius Maximus. When all are like Turtle, there will be no war and no politicians, and peace and happness will reign over all.
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#1. To: Turtle (#0)
Good piece.
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