Saturday, January 17, 2004

Brain Evolution Don't miss this short article from the ever-useful New York Times, describing the discovery of a gene, called ASPM, which has a major impact on the size of our brains. People possessing a non-functional copy of this gene suffer from microcephaly, a dramatically shrunken brain. Comparing the version of this gene with that found in chimpanzees, gorillas, monkeys, cows and other animals reveals that natural selection caused major changes to accrue in this gene over the last eighteen million years. The changes became increasingly dramatic after the human/chimpanzee split roughly five million years ago.

The changes in this gene appear to be correlated with steadily increasing brain size in hominid evolution. Furthermore, unlike most human genes, which appear in groups of similar members that arise as the result of gene duplication events, ASPM exists only as a single copy. This, coupled with the enormous selective advantage of larger brains, could go a long way towards explaining one of the great mysteries of evolutionary biology: What caused the rapid growth of brain size in humans after our split form the chimpanzees?

Also note that, creationist protestations notwithstanding, Darwin's theory of evolution continues to pay dividends in everyday scientific work.


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