Although an individual human is shaped by a combination of genetics and environment, the environment shapes a species only indirectly, through the mechanism of natural selection. As a species, then, the genetic makeup—the genome—is critical. We've long known that we share well over 90% of our genetic material with the chimpanzees. Now that the human genome has been read and we have a draft of the chimpanzee genome, we have a better handle on what those genetic differences are.
Each "word" of the genetic code consists of three units known
as nucleotides. Nucleotides come in four kinds, and it appears that we and the chimps
have accumulated about 35 million nucleotide differences since we split apart some 5 to
7 million years ago. We've also accumulated about 5 million other differences, such
as short segments of genetic material added or deleted or rearranged. Although these
differences may sound large, it turns out that taking all of them into consideration
still leaves us about 96% identical. As the French say regarding a different subject,
"Viva la difference!"
Listen to the Audio (mp3 format) as recorded by KTEP, Public Radio for the Southwest.
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.
Our close relative having an afternoon snack. Photograph courtesy of the Library of Congress.
Anonymous. 2005. This issue. Nature 437:ix.