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The human brain shows strikingly different patterns of gene expression compared to the chimpanzee brain, a difference that isn't seen in other parts of the body like the liver and white blood cells, an international research team reports.

Their study in the 12 April issue of the journal Science, published by the American Association for the Advancement of Science, may shed light on why chimps and humans are so genetically similar--humans and chimpanzees share 98.7 percent of their DNA sequences--yet so mentally and physically different.

Zeroing in on these differences could also help scientists learn more about the genetics underlying medical traits such as susceptibility to AIDS, malaria, and Alzheimer's disease, say the Science researchers, led by Svante Pbo of the Max-Planck-Institute of Evolutionary Anthropology in Leipzig, Germany.

The differences between humans and their closest relatives are more a matter of quantity than quality, according to the report. Differences in the amount of gene and protein expression, rather than differences in the structure of the genes or proteins themselves, distinguish the two species. The overall pattern suggests that the human brain may have experienced accelerated evolutionary change.

Pbo and colleagues searched for these differences using gene chips carrying tiny dabs of human DNA, representing about 18,000 genes. The chip DNA interacted with genetic material purified from brain and liver tissue collected from humans, chimpanzees, and macaque monkeys, allowing the researchers to measure levels of gene expression in each of the species.

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Contact: Lisa Onaga
lonaga@aaas.org
202-326-7088
American Association for the Advancement of Science
11-Apr-2002