Author: Metcalfe David
Date: August 2007
It is an astonishing fact that man shares 99% of his genes with the humble chimpanzee. Now, a team of researchers from Duke University has shown that differences in dietary preference and cognition are largely due to regulation of genes rather than their sequence.
According to Ralph Haygood, first author on the paper that appeared in Nature Genetics earlier this month, "positive selection, the process by which genetic changes that aid survival and reproduction spread throughout a species, has targeted the regulation of many genes known to be involved in the brain and nervous system and in nutrition." Although researchers have previously found little difference in the sequence of genes between man and chimpanzee, this is the first time that a study has taken a genome-wide approach to investigating regulatory genetic components.
Haygood's team examined the regulatory sequences that lie adjacent to genes shown to be involved in nutritional or neural processes. These regulatory sequences are the structures to which proteins bind in the cell to switch particular genes on' and off' as required. In particular, they looked at 6,280 regulatory sequences in humans, common chimpanzees, and rhesus macaques. By measuring the rate of evolution, these researchers were able to show that significant changes have occurred in regulatory regions between human and chimpanzee DNA. It was not, however, until the macaque genome was published in 2005 that they could introduce a third, closely-related primate to compare the human and chimpanzee sequences.
Although the present work strongly suggests that neural and dietary adaptations have arisen due to the evolution of regulatory sequences, the final test of this theory awaits the publication of further primate genomes. According to the authors, "much further work is needed to confirm and elaborate this suggestion. [our approach] will gain power by incorporating sequences from additional primates."
By David Metcalfe