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Mapping similarities between humans and chimpanzees
Edward R. Winstead


Scientists have created a comparative map of DNA sequences found in humans and chimpanzees, our closest relative. The map confirms previous estimates of the high degree of genetic similarity between the two species. In one of the largest comparisons of human and chimpanzee genomic sequence to date, the researchers calculated that the shared sequences were 98.77 percent identical.

The researchers aligned some 77,000 chimpanzee DNA fragments to corresponding segments of the human genome sequence. They identified several regions in the human genome that appear to differ from similar regions in chimpanzees and gorillas; these differences may represent significant events in evolution. Asao Fujiyama, of the RIKEN Genomic Sciences Center in Japan, led the study.

"Because chimpanzees are our closest relatives, the differences between us are less than with any other species, yet these differences are more likely to be important," the researchers write in Science. "Thus, comparisons between humans and chimpanzees are the most efficient and effective approach to understand what makes us human."

Images of human and chimpanzee chromosomes used in the study.

The DNA came from three chimpanzees—two males and one female. When aligned, the fragments covered about 49 percent of the human genome sequence. The quality—and therefore the usefulness—of the map will be improved as the human genome sequence is refined.

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Fujiyama, A. et al. Construction and analysis of a human-chimpanzee comparative clone map. Science 295, 131-134 (January 4, 2002).

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