A massive gene-comparison project involving two Cornell University scientists, and reported in the latest issue of the journal Science (Dec. 12, 2003), found these and many other differences in a search for evidence of accelerated evolution and positive selection in the genetic history of humans and chimps.
In the most comprehensive comparison to date of the genetic differences between two primates, the genomic analysts found evidence of positive selection in genes involved in olfaction, or the ability to sense and process information about odors. "Human and chimpanzee sequences are so similar, we were not sure that this kind of analysis would be informative," says evolutionary geneticist Andrew G. Clark, Cornell professor of molecular biology and genetics. "But we found hundreds of genes showing a pattern of sequence change consistent with adaptive evolution occurring in human ancestors." Those genes are involved in the sense of smell, in digestion, in long-bone growth, in hairiness and in hearing. "It is a treasure-trove of ideas to test by more careful comparison of human and chimpanzee development and physiology," Clark says.
The DNA sequencing of the chimpanzee was performed by Celera Genomics, in Rockville, Md., as part of a larger study of human variation headed by company researchers Michele Cargill and Mark Adams.
Celera generated some 18 million DNA sequence "reads," or about two-thirds as many as were required for the first sequencing of the human genome. Statistical modeling and computation was done by Clark and by Rasmus Nielsen, a Cornell assistant professor of biological statistics and computational biolo
Contact: Roger Segelken
Cornell University News Service