Some believe culture has effectively blocked the action that natural selection might have on our brains.
The human brain may still be evolving, new research suggests. New variants of two genes that control brain development have swept through much of the human population during the last several thousand years, biologists have found.
The evolution of a large, complex brain has been the defining feature of the human lineage – although human brain size has not changed over the past 200,000 years. But it is not apparent whether the new genetic adaptations discovered in human brains have any effect on brain size, or intelligence.
What is more, not everyone possesses the new gene variants, potentially inflaming an already controversial debate about whether brains of different groups of people function differently.
"Whatever advantage these genes give, some groups have it and some don't. This has to be the worst nightmare for people who believe strongly there are no differences in brain function between groups," says anthropologist John Hawks of the University of Wisconsin in Madison, US.