September 10, 2005
The human brain is still evolving and may get bigger, a study of two genes linked to the organ's size and complexity suggests.
"If our species survives for another million years or so, I would imagine that the brain by then would show significant structural differences from the human brain of today," said Bruce Lahn, an assistant professor of human genetics at the University of Chicago.
Dr Lahn and his research team studied two genes called microcephalin and ASPM. People with mutated, inactive versions of these genes have very small brains - a condition called microcephaly. Comparing the DNA code of these two genes in apes and humans, the researchers found that both genes had changed significantly during millions of years of evolution.
To find out if this process was still occurring, they tested more than a thousand people from 59 different ethnic backgrounds. The results were published in the journal Science yesterday.
The researchers identified one version of the microcephalin gene that they calculated arose about 37,000 years ago - about the time humans began to produce art and music, practise religion and use sophisticated tools. About 70 per cent of people now have this particular version.
AdvertisementAbout 30 per cent of people also have a version of the ASPM gene that arose even more recently, about 5800 years ago, about the time that people began to farm, write and build cities.
To have become so common in the human population in such as short time, these particular versions of the genes must be very advantageous for survival.
While linked to brain size, the genes could have many roles, such as affecting how people think, their personality or susceptibility to mental illnesses.
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