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Vol. 20, No. 5
Science Refutes Orthodoxy — Again
Racial differences are real and increasing.
Gregory Cochran and Henry Harpending, The 10,000 Year Explosion: How Civilization Accelerated Human Evolution, Basic Books, 2009, 288 pp., $27.00.
Reviewed by Thomas Jackson
The 10,000 Year Explosion is such a subversive book it is surprising it was brought out by a mainstream New York publisher. The authors, both of whom teach anthropology at the University of Utah, steer clear of politics, but the scientific findings they describe have such obvious policy implications that they will reduce liberals to spluttering incoherence — if liberals can bring themselves to read the book.
This volume shatters one of the obligatory doctrines by which the Left lives: that Homo sapiens hardly evolved at all after modern man ventured out of Africa, and that although groups differ in appearance their brains are identical. This is clearly nonsense, but the great strength of this book is to have marshaled so many contemporary genetic discoveries that prove it is nonsense. Far from slowing down, evolution has been speeding up, and the authors argue that for the last several thousand years it has been roaring along 100 times faster than during the Stone Age, making different populations increasingly unlike each other. “The biological equality of human races,” the authors write, is “about as likely as a fistful of silver dollars all landing on edge when dropped.”
If one accepts the theory that modern humans first evolved in Africa and began colonizing the rest of the world 50,000 to 60,000 years ago, it is obvious that there has been enormous evolutionary change since that time. Zulus and Danes presumably had a common ancestor about the time humans left Africa, but are now so different from each other that standard taxonomies might well classify them as separate species.
Nature is full of dramatic change. When fish are trapped in caves they lose their eyesight in just a few thousand years. Rapid evolution also occurred when the sea rose at the end of the last Ice Age, 11,500 years ago, and herds of elephants were cut off from the mainland on what became islands. Size is not an advantage on an island, and the fossil record shows that the elephants shrank in height from 12 feet to three feet in just 5,000 years. Elephants have about the same 20-year generation span as humans.
Professors Cochran and Harpending point out that even more rapid evolution is taken for granted by ranchers and farmers, who are constantly raising stock that did not exist 100 or even 15 years ago. They note that every breed of dog has evolved from wolves, which were domesticated 15,000 years ago, and that most of the breeds we recognize today are only about 200 years old. A Russian scientist managed to breed tame foxes in just 40 years — ten generations — by selecting only for tameness and friendliness. The pet foxes lost their musky, fox smell, wagged their tails when they were happy (which wild foxes do not), and liked to lick people’s hands.
People consciously direct the evolution of plants and animals, but the authors point out that the process is no different from the rigors of natural selection — just quicker. Much as the race deniers hate to admit it, humans in different environments evolved in sharply different directions. As the authors conclude, “We expect that differences between human ethnic groups are qualitatively similar to those between dog breeds.”
What, however, caused human evolution suddenly to speed up ten to twelve thousand years ago? For Professors Cochran and Harpending, the short answer is “agriculture.” It did so in two ways: by sharply increasing the number of people and by radically changing the environment in which they lived.
More humans meant more children, and therefore more mutations. Most babies are born with about 100 mutations, all but one or two of which are in DNA that does not seem to do anything and therefore have no effect. Those that make a difference are usually harmful or neutral but it is the occasional helpful mutation that drives evolution. Sixty thousand years ago, before the expansion out of Africa, there were perhaps only about 250,000 humans. By the Bronze Age, 3,000 years ago, there were 60 million, so a mutation that would have taken 100,000 years to occur could appear in just 400 years. Evolution was painfully slow among Paleolithic proto-humans because beneficial mutations show up so rarely in tiny populations.
Large populations are therefore a reservoir of new mutations and their size hardly slows down the propagation of good genes. According to the authors, a genetic leg up is like the flu, and can sweep through a population of 100 million in only twice the time it takes to go through a population of just 10,000.
The power of agriculture
Agriculture also brought perhaps the most dramatic change in the biological and social environment our species has ever experienced. Farming meant that for the first time in their existence Homo sapiens stayed in one place, and could therefore own more things than they could carry with them. They could become wealthier than their neighbors, and had to guard possessions against theft. Farmers could produce more food than their families needed, and this gave rise to commerce, division of labor, artisans, and non-productive elites. This social environment was completely new.
“Eventually [after the adoption of farming] there must have been many people with personality types that hadn’t existed at all among our forager ancestors.”
Of particular significance from an evolutionary point of view were the change of diet, domestication of animals, and population densities. The first agricultural diets had little variety and were not nearly as nutritious as the meat humans had been eating for millennia. With little protein in their diets, farmers were as much as five inches shorter than hunters, and any mutations that helped farmers get more out of a cereal diet got around quickly. At the same time, the widespread use of fire to prepare and soften food meant people could evolve smaller teeth than those necessary during the Paleolithic period.
Domestication and herding meant living with animals, and people began to catch their diseases. At the same time, villages produced heaps of rubbish that attracted rats and other disease carriers. New kinds of pestilence ran through populations that were far denser than before, so there was a high demand for genes that gave resistance to disease. Farmers invariably discovered fermentation, so selective pressure also began to weed out excessive susceptibility to alcohol.
In dense communities, in which wealth could be accumulated and traded, complex speech is more important than among hunters. Ownership of land and livestock required new rules and ways to enforce them. People had more to think about, more possessions to look after, and thieves and con men to deal with. All this pushed evolution in new directions.
The nature of agriculture changed human nature. Farming requires more planning and self-restraint than hunting; at the very least, farmers must save seed corn for the next year no matter how hungry they get during the winter. Meat, on the other hand, goes bad in a few days, so hunters gorged themselves rather than save. Farming favored deferred gratification.
Likewise, if farmers worked hard they could make permanent improvements to their land and build safe, comfortable houses. There was no incentive for hunters to build things or accumulate anything they could not move. Once their bellies were full they goofed off until the next hunt. Farming favored mutations that produced steady toilers.
People who lived in densely packed, permanent settlements also had to control anger and violence. If hunters had nasty neighbors they could just move away. Farmers could not abandon their farms, so they had to learn to live with people they did not like. Once governments arose, people had to submit to rulers, and the impulse to reach for a weapon was no longer so adaptive. As the authors explain, “Eventually there must have been many people with personality types that hadn’t existed at all among our forager ancestors.”
There is direct, genetic evidence that agriculture caused rapid genetic change. Sophisticated techniques can indicate how recently distinctive genetic patterns evolved in different populations, and more new genes were sweeping through European and Asian populations about 5,500 years ago than at any time before or since. The huge changes brought on by agriculture were probably the cause.