Book review: The 10,000 year explosion: how civilisation accelerated human evolution
This brief book review by Michael Sargent was first published in the 2011/2012 Mill Hill Essays.
The anthropologist authors of this book suggest that human cultural evolution in the last 10,000 years has been underpinned by an accelerating rate of selection of new genetic variants. This contrasts sharply with the once widely accepted view that all recent human evolution was only cultural. This accessible and fascinating book discusses many traits that emerged in the last ten millennia and which affect skull size, lactose tolerance, speech, pigmentation, metabolic pathways and resistance to microbes. With a proper regard for evidence, the authors also dip fearlessly into areas where angels fear to tread: intelligence and interbreeding with Neanderthals. Less provocative is their example of the lactose-tolerance gene variant that allows adults to consume milk comfortably. This trait appeared first amongst the Kurgan people of South-West Asia, the inventors of dairy farming. The mutation conferred enormous selective value on carriers and on the entire group through the competitive edge conferred by their high quality foodstuffs. Most modern Europeans are descended from these lactose-tolerant dairy people because of a history of military conquest and cross-cultural mating. The book concludes with intriguing speculation about the origins of the extreme intellectual prominence amongst Ashkenazi Jews that has emerged in the last two centuries. The authors see a link between this and the high incidence of genetic diseases like Tay-Sachs that cause accumulation of brain sphingolipids. The key suggestion is that heterozygotes for these recessive mutations develop superior interconnections between brain cells (rather analogous to the heterozygote advantage found with sickle cell anaemia that protects against malaria). While conclusive proof of such an argument is likely to remain elusive, there is substantial circumstantial evidence.
The 10,000 year explosion: how civilisation accelerated human evolution, by Gregory Cochran and Henry Harpending is published by Basic books, 2009.