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From: dd@beta.UUCP (Dan Davison)
Newsgroups: sci.misc,sci.bio,soc.women
Subject: Re: Univerrsal Common Female Ancestor
Message-ID: <11066@beta.UUCP>
Date: Sat, 10-Oct-87 02:23:39 EDT
Article-I.D.: beta.11066
Posted: Sat Oct 10 02:23:39 1987
Date-Received: Mon, 12-Oct-87 04:54:56 EDT
References: <894@phoenix.Princeton.EDU> <1248@bsu-cs.UUCP>
Organization: Los Alamos Natl Lab, Los Alamos, N.M.
Lines: 42
Keywords: Eve?
Summary: it's mitochondrial DNA, NOT nuclear DNA, we're talkin' 'bout here
Xref: mnetor sci.misc:536 sci.bio:713 soc.women:7722

In article <1248@bsu-cs.UUCP>, dhesi@bsu-cs.UUCP (Rahul Dhesi) writes:
> In article <894@phoenix.Princeton.EDU> elturner@phoenix.Princeton.EDU 
> (Edwin L Turner) writes:
> 
>      All living people (or at least ~99% of them) have a single common
>      female ancestor on their purely maternal line....
> 
A small correction:  this refers ONLY to mitochondrial DNA, not nuclear DNA,
and so for the vast majority of the population says nothing about a single
common female ancestor.  Nor does it imply a population bottleneck 200,000
years ago.  It seems to me this "Eve" business has been really messed up
by the media.  (1) She's the "eve" for mitochondria only.  (2) It makes
no statement about the human population because 200,000 years is *tiny*
relative to the tempo and mode of primate mitochondrial evolution.  [See
the paper by Wesley Brown et al., J. of Molecular Evolution, 18:225-239
1982, "Mitochondrial DNA sequences of Primates: Tempo and Mode of 
Evolution"]

Note that the other women alive at the time could have left mitochondria
in their descendants who did not have female offspring as recently as
2 generations ago, thus making it look as though there is an "Eve".  
I'd suggest those interested in this topic who want a more intelligent
handling of the topic see the September/October issue of The Sciences,
pp. 30-37.  Note, though, that even The Sciences blew it: the cover
says "Who was the mother of all mankind?".  Amazingly fuzzy thinking!
I am quite amazed at the degree of misinformation this work has caused.

By the way, "molecular clock" fans:  this may be one of the few cases
where a molecular clock has been claimed and there is a clear cut case
which supports the argument.  For those non-biologists reading this,
the "molecular clock" was proposed by Allan Wilson in a review in
the Annual Review of Biochemistry in 1977.  The argument goes that the
rate at which base changes occur ("mutation") happens, on average,
regularly over long periods of time.  If you can determine the "tick"
of the clock, you can do phylogenetic work to determine the divergence
time of two species from sequence comparison alone.  

This idea has so many holes in it I must admit I do not understand the
apparent general acceptance of the idea.

dan davison/t-10 ms k710/theoretical biology/los alamos national lab/
los alamos, nm 87545/dd@lanl.gov/...cmcl2!lanl!dd/dd@lanl.uucp