I wrote before about ASPM, a gene that might play a role in generating our big brains. There's an article in today's New York Times, Evolution of Gene Related to Brain's Growth Is Detailed, that describes recent results in sequencing this gene in other primates.

The gene, known as the ASPM gene, has been under steady selective pressure throughout the evolution of the great apes, a group that includes orangutans, gorillas, chimpanzees and humans, Dr. Lahn and colleagues say in an article being published today in the journal Human Molecular Genetics. By contrast, the versions of the gene possessed by monkeys, dogs, cats and cows show no particular sign of being under selective pressure.

The progressive change in the architecture of the ASPM protein over the last 18 million years is correlated with a steady increase in the size of the cerebral cortex, the part of the brain responsible for higher cognitive function, during the ape and human lineage. Evolution has been particularly intense in the five million years since humans split from chimpanzees.

"There has been a sweep every 300,000 to 400,000 years, with the last sweep occurring between 200,000 and 500,000 years ago," Dr. Lahn said, referring to a genetic change so advantageous that it sweeps through a population, endowing everyone with the same improved version of a gene.

The article is published by Bruce Lahn in the latest issue of Human Molecular Genetics, and unfortunately the terms of our library's license for that journal mean I won't be able to get it easily for another year. Dang it.