WORLD SCIENCE

"Long before it's in the papers"
June 20, 2005

Brain flexibility, not size, gave us our intelligence, researchers say

August 24, 2004
Special to World Science

Researchers have traditionally assumed that a gradual increase in human brainpower over evolutionary history corresponds to an increase in brain size. Not so, Spanish researchers say: instead of greater size, they insist, we have to thank genes that improved brain cells' ability to change and repair their interconnections, boosting learning ability. 

"Brain size in the Homo genus not only has not increased during the last 150,000 years but has also experienced a slight reduction in the last 35,000 years," write Enric Bufill and colleagues, with Hospital General de Vic, Spain, in the July issue of the research journal Revista de Neurologia. 

Instead, mutations—including a key mutation in a gene called apolipoprotein E, about 220,000 years ago—improved neurons' ability to rewire themselves, they write. This mutation's "selection and expansion may have continued until a relatively recent period that coincides with the emergence... [of] complex symbolic culture," they write. The culture itself may then have increased selective pressure for the good mutations, they add.

—EJL

Front image credit: National Institutes of Health

WORLD SCIENCE

WORLD SCIENCE