taken from:
Genetics: An Evolutionary Mate for 'Eve"?
Genetics: An Evolutionary Mate for 'Eve"?
by Boyce Rensberger
The Washington Post
About 10 years ago, molecular biologists found evidence in human genes that all people share a
common female ancestor, dubbed Eve,- who lived in Africa about 200,000 years ago. The claim has
been challenged on both genetic and fossil evidence, and it has been supported by a repetition of the
same kind of analysis.
Now comes corroboration from a different kind of genetic study. While the earlier claim was
based on DNA transmitted only through the maternal lineage (mitochondrial DNA), the new report
uses DNA transmitted-and possessed only by males (the Y chromosome).
Michael F. Hammer, a researcher in
molecular evolution at the University of Arizona in
Tucson, reported in the Nov. 23 Nature that his
analysis of a part of the Y sex chromosome
indicates that modern humans descended from a
common male ancestor who lived 188,000 years
ago. Although the new report does not say where
that ancient man, whom some are cauing "Adam,'
lived, his age is close enough to Eve's for this kind
of work.
Both analyses are based on counting
mutations that distinguish a portion of one modern
person's DNA from that of others and using a
"molecular clock" that assumes the mutations arise
at a known, constant rate.
Even though the studies refer to a single man
or woman in the past, they do not imply that those
people were a couple or even that they were the only parents of all humans. Their primary
significance is in pointing to the time when anatomically modern human beings, Homo sapiens
sapiens, evolved from a more primitive ancestor, generally thought to be an archaic form of Homo
sapiens. Most experts think the founders of the modern species numbered around 10,000.
Many anthropologists believe this transition happened in Africa and that the subspecies spread
to other parts of the world, replacing more primitive foms of humans such as Homo erectus. Others,
however, dispute the genetic evidence and argue that modern people evolved in many parts of the
world as products both of the people already living there and of immigrants.
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