The 10,000 Year Explosion

The 10,000 Year Explosion: How Civilization Accelerated Human Evolution by Gregory Cochran and Henry Harpending, Basic Books, 2009. 

Recent Human Evolution

This book describes how human evolution did not stop with the emergence of homo sapiens two hundred thousand years ago, but instead continues even now. In fact, they argue, the rate of human evolution is speeding up.

Race

The authors discuss the scientific arguments made by the opponents of the concept of race. The opponents of the concept of race point out that there is more genetic variation within each race than there is between the races. But the same is also true for dog breeds, and no one is challenging the concept of dog breeds. The explanation for why there is so much variation within a race or breed is that most of these within-breed genetic differences have only a minor impact on the traits that are expressed by the genes. Some genes are more important than others.

Lactose Tolerance

The allele that allows adults to digest the lactose sugar in milk originated in the Eurasian steppe. This enabled adults to gain nourishment from the milk of domesticated cattle. The authors argue that it was this advantage that enabled the Indo-Europeans to spread to Europe and India. 

Ashkenazi Jews

European Jews are called Ashkenazi, after the Hebrew word for Germany. During the Middle Ages in Europe, the Jews were limited to being money lenders. This environmental factor selected for intelligence. Ashkenazi Jews tend to be more intelligent than Sephardic and Mizrahi Jews, and the authors propose that this is due to changes in their neurological genes. To support this hypothesis, the authors point out that Ashkenazi Jews are prone to hereditary neurological diseases. The Ashkenazi neurological disorders include: Tay-Sachs, Gaucher’s disease, familial dysautonomia, Niemann-Pick lysosomal storage disease, the Canavan disease of infancy, torsion dystonia, and mucolipidosis type IV (often misdiagnosed as cerebral palsy). Some of these neurological diseases create a marked increase in the growth of dendrites.