Our brains have shrunk in the past 20,000 years. In The Domesticated Brain, Bruce Hood argues that it’s a result of living together in societies

“TWENTY thousand years ago, the average human brain was 10 per cent larger than it is today. Some people, such as David Geary, a psychologist at the University of Missouri in Columbia, claim that the dip in cranial capacity marks our dwindling intelligence. Others, like John Hawks, an anthropologist at the University of Wisconsin-Madison, attribute it to improved brain efficiency.

But for Bruce Hood, the author of The Domesticated Brain and a psychologist at the University of Bristol, UK, the shrinkage is best explained by changes in society. “We have been self-domesticating through the invention of culture and practices that ensure that we can live together,” he writes. Our brains, he believes, are getting downsized by domesticity.

Domestication tends to have that effect. According to Hood, every species that has been domesticated by humans has lost brain capacity as a result. Bred for passivity, their testosterone decreases, reducing the size of all organs. Dogs are a good example and the effect on their behaviour is telling: where wolves will try to solve a problem through cunning, dogs are adept at soliciting help from their masters.”

Read the whole article in New Scientist: http://www.newscientist.com/article/mg22229690.900-has-social-living-shrunk-our-brains.html#.U4BCJvmSyuJ