Dr. Robert Jastrow holds models of man's brain, showing its smaller size of 2 million years ago and the modern brain. (Photo : Getty Images)
Chinese researchers may have just found out why the average Asian brain is significantly larger than the average African or European brain.
A study from the Chinese Academy of Sciences' Kunming Institute of Zoology indicates that the answer to this question may lie with Darwinian selection in East Asian populations.
The study was published late last month in the journal Human Genetics. It indicates that genetic mutations may have led to bigger brains in the group due to natural selection.
The discovery was first put forth three decades ago by a team of American researchers after they have studied more than 20,000 present-day human skulls coming from different parts of the world. It was considered the largest survey of brain sizes.
The survey revealed that the cranial capacity of East Asians was 1,314 cubic centimeters, which was bigger compared to the Europeans averaging at 1,362 and Africans averaging at 1,268.
A gene called CASC5 was identified by the Chinese research team. This is one of eight genes that regulate the human brain size, and may be the key on solving the puzzle regarding cranial sizes.
The gene's genetic mutations in humans are relatively new, which makes it unique. The researchers found a "high frequency" of four mutations that increased the brain sizes among East Asians after isolating and comparing CASC5 mutations.
The researchers wrote in the paper: “At the population level, our results suggest a selection of CASC5 in East Asian populations, which seems to favor a larger grey matter volume of the brain. By contrast, no signal of selection was detected in Europeans and Africans.”
Scientists, however, points out that the drivers behind such change are still unclear for the time being.
Su Bing, the team lead of the research team, said: “Scientific research has found no evidence, none at all, to support the existence of intellectual difference among races."