"Myth of Eve"

[rowe@lepomis.psych.upenn.edu (Mickey Rowe)]

Sorry to dredge something up from a couple of weeks ago, but I
couldn't let this pass and couldn't get to it sooner.  Steve Cole sent
us a story from Reuter:

> All about Eve not just one, and much older
>  By Deborah Zabarenko
>  WASHINGTON, Dec 21 (Reuter) - Bad news for Eve: a new report
> disputes the theory that one genetic mother of us all lived 200,000
> years ago in Africa, arguing that there had to be some 100,000
> "Eves" existing much earlier in time.
>  The report in Friday's edition of the journal Science that our
> earliest genetic forbears existed perhaps 60 million years ago, long
> before human beings walked the earth, contradicts the "mitochondrial
> Eve" theory advanced eight years ago.

I won't repeat the article in toto, because I still can't take the
time to point out all of the errors (I can't believe that nobody else
complained about the author's abuse of the word "molecule"; in one
place she used it where she should have written "cell"!  Where have
all the great nit-pickers gone? ;-).  I'd just like to comment that
the Reuter article did little but spread some of the misinformation
that the Science article was trying to dispel.  Contrary to the Reuter
article's claim, the _Science_ article doesn't dispute the existence
of our mitochondrial mother; it just attempts to clarify the meaning
of the poorly named "Eve".  If you understood Wilson et al. when they
originally wrote about the pinpointing of our mitochondrial mother in
time and space, then you don't have to change your understanding much
as a result of the Science article.  If there's interest, I might be
persuaded to elaborate, but for now suffice it to say that the Reuter
article on the subject should best be completely forgotten.  I'll
close by blasting her last sentence (because it's an easy target):

> The Y-chromosome is passed only from fathers to children, just as
> mitochondrial DNA is passed only from mothers.

This is an oversimplification because recombination does occur between
X and Y chromosomes during the creation of sperm.  That is, if you're
a male, some of the genes on your Y chromosome came from your father's
X chromosome (and hence from your father's mother).  If you're a
woman, some of the genes on one of your X chromosomes came from your
father's Y chromosome.  There are *regions* of the Y chromosome that
do not crossover, and hence are conserved along male lines.  The
entire Y chromosome is not such a beast, however.

-- 
Mickey Rowe     (rowe@lepomis.psych.upenn.edu)