Saturday, March 21, 2009

The 10,000 Year Explosion

Just finished The 10,000 Year Explosion by Gregory Cochran and Henry Harpending. The thesis of this book is that the changing environments encountered by human populations since the original excursion out of Africa ~50,000 years ago - and more recently through the introduction of agriculture, have led to substantial and differential genetic changes in various human populations. Therefore, to understand the deep history of humanity, we need a combined cultural-genetic analysis in which each component couples to the other.

Key ideas include:
  • The evolved disease-resistance of Europeans + their diseases effectively destroyed the Amerindian populations of North and South America, which led to a relatively easy colonisation by quite small forces. Compare the European inability to colonise Africa, rich in its own diseases to which the indigenous Africans were far better adapted: they didn't die off.

  • The spread of the original Indo-European speakers from their Pontic-Caspian Steppe homeland was, the authors argue, driven by a lactose-tolerating mutation which allowed those nomadic invaders to consume milk. This is a far more efficient energy source than slaughtering cattle, supporting five times as many warriors per square kilometre.

  • And then the explanation of the superior intelligence (~0.7 std. dev.) of the Ashkenazi Jews due to strong selective pressure in their taxation, money lending and management niche over the last thousand years in northern Europe ... and the price in genetic diseases of the nervous system they pay for their IQ-boosting mutations.
I suspect the enemies of applying evolutionary theory to human development will have to die-off before the paradigm gets decisively shifted, but to an honest evolutionist, the approach of this book cannot be faulted.

We are at the earliest stages of differential genetic analysis, and I expect that the bubbling ideas and historical scenarios outlined in such a clear and entertaining way in this book will be substantially developed and refined in the coming years.