This article was taken from SciBoard of Louisville University.
THE EVE THEORY
/Bio #6016 09-APR-92 19:39
To: ** ALL **
Computer researchers have apparently found a major flaw in the notorious
"Eve" hypothesis which purported to find a woman who was in the family
tree of every living human being, and who by a "biological clock" had
been estimated to have lived around 200,000 years ago.
This theory was proposed by computer analysis of "mitochondrial DNA."
Mitochondria are cell organelles that are -always- inherited from your
mother; by contrast, your nuclear DNA is half yours and half your
mother's. (Well, maybe in Kentucky. I meant, half your father's.)
The authors of this hypothesis, which was originally proposed by Allan
Wilson of Berkeley, had examined human mitochondrial DNA for random
mutations and concluded that the earliest differences could be found
between San Bushmen and everybody else. From this they concluded that a
common ancestor of everybody lived in Africa, and that she lived 200,000
Bone and fossil types had been hostile to this hypothesis, because
Wilson made some statements that implied that a superior group of humans
arising at that time had -replaced- all previously existing humans. On
the other hand, they didn't have the skills in probability or genetics
to attack his research directly.
Unfortunately for Wilson, it appears that a flaw in the computer
analysis he used dooms his original findings. Mathematically, you
cannot deduce how many intermediate forms of mitochondrial DNA may have
existed between one set and an ancestral set, merely by counting the
different forms that appear -now-. The greatest divergence in the
genetic sequence (which Wilson found between the Bushmen and the rest of
us) does -not- imply that the Bushmen are closer to the ancestral stock.
Wilson's theory may still be true. More research will need to be done.
I don't have a problem with a single human ancestor existing 200,000
That would put the "common ancestor" beyond even the point where
Neanderthals become identifiable as a separate group.
Mitochondrial DNA is like a family name. It is transferred by only one
sex - in this case, the woman. A father may have seven children, and
all of them are daughters. These daughters can marry and have children
of their own. Yet, under the traditional naming system, the father's
name has been lost. All of his children were daughters. In the stream
of "family name" inheritance, his is a dead branch; in the stream of
genetic inheritance it is not. Mitochondrial DNA will also be lost, not
only by those who beget no children, but by all women who have only
sons. Those sons may pass their mother's genes. But they cannot pass
their mother's mitochondrial DNA.
So the wilder speculation that has come out of the "Eve" hypothesis ---
that there was a group of early humans who managed to -replace- all
others, and that all genetic material not traceable to this group has
been lost --- just doesn't follow from it even if you accept it at face