Dna chimpanzee vs human1/7/2024 ![]() ![]() In addition to the great departure in smell perception, differences in amino acid metabolism also seem to affect chimps' and humans' abilities to digest dietary protein and could date back to the time when early humans began eating more meat, Clark speculates. "The signature of positive selection is very strong in both humans and chimps for tuning the sense of smell, probably because of its importance in finding food and perhaps mates," says Clark. ![]() In a sense, this method asks: What are the genes that make us human? Or rather, what genes were selected by natural selection to result in differences between humans and chimps?" The study started with almost 23,000 genes, but this number fell to 7,645 because of the need to be sure that the right human, chimp and mouse genes were aligned.Īccording to Clark, all mammals have an extensive repertoire of olfactory receptors, genes that allow specific recognition of the smell of different substances. Clark explains, "By lining up the human and chimpanzee gene sequences with those of the mouse, we thought we might be able to find genes that are evolving especially quickly in humans. Some of the analysis, which also compared the mouse genome, used the supercomputer cluster at the Cornell Theory Center. Statistical modeling and computation was done by Clark and by Rasmus Nielsen, a Cornell assistant professor of biological statistics and computational biology. 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.Ĭelera generated some 18 million DNA sequence "reads," or about two-thirds as many as were required for the first sequencing of the human genome. "It is a treasure-trove of ideas to test by more careful comparison of human and chimpanzee development and physiology," Clark says. "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. ![]() Clark, Cornell professor of molecular biology and genetics. "Human and chimpanzee sequences are so similar, we were not sure that this kind of analysis would be informative," says evolutionary geneticist Andrew G. 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. 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. Specifically, two key differences are how humans and chimps perceive smells and what we eat.Ī massive gene-comparison project involving two Cornell University scientists, and reported in the latest issue of the journal Science (Dec. ![]() Nearly 99 percent alike in genetic makeup, chimpanzees and humans might be even more similar were it not for what researchers call "lifestyle" changes in the 6 million years that separate us from a common ancestor. ![]()
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