Excerpt from “Was There an Eve?”
In a 1987 article in the prestigious journal Nature,
three biochemists published a study of mitochondrial DNAs from 147
people living on five continents. The biochemists stated, “All these mitochondrial
DNAs stem from one woman who is postulated to have lived about 200,000
years ago, probably in Africa.”1
The story became a sensation. The woman was called the African Eve, and Newsweek put her on its cover. There she was—the single ancestor of all living human beings.
Eve was one in a population of primitive human beings. But all human lineages not deriving from her have perished. For students of human evolution, one important implication of this finding was that Asian populations of Homo erectus, including the famous Peking ape men, must not have been among our ancestors. Those ape men couldn’t have descended from Eve, it was thought, because they lived in Asia before 200,000 years ago.
Mitochondrial DNA (mtDNA) carries genetic instructions for the energy-making factories of human cells. Unlike other genetic material, it is transmitted to offspring only from the mother, with no contribution from the father. This means that the descent of mtDNA makes a simple branching tree that is easy to study. Computer studies on the sample of 147 people (who represent the world population) show that the original ancestral trunk divided into two branches. Only Africans descended from one branch. The rest of the population, as well as some Africans, descended from the other. The inference was that the stem was African. In 1991 another analysis of exact mtDNA sequences from 189 people confirmed this and indicated that Eve was roughly our ten-thousandth great-grandmother.
The Fall of Eve
Unfortunately, however, Eve quickly fell down. In 1992 the geneticist Alan Templeton of Washington University stated in the journal Science, “The inference that the tree of humankind is rooted in Africa is not supported by the data.”2 It seems that the African Eve theory evolved from errors in computer analysis. . . .
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|1.||Cann, R., Stoneking, M., and Wilson, A., 1987, “Mitochondial DNA and Human Evolution,” Nature, Vol. 325, January 1.|
|2.||Begley, S., 1992, “Eve Takes Another Fall,” Newsweek, March 1.|
Copyright © 2004 by Richard L. Thompson