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From: elturner@phoenix.Princeton.EDU (Edwin L Turner)
Newsgroups: sci.misc,sci.bio,soc.women
Subject: Univerrsal Common Female Ancestor
Message-ID: <894@phoenix.Princeton.EDU>
Date: Fri, 9-Oct-87 15:46:19 EDT
Article-I.D.: phoenix.894
Posted: Fri Oct  9 15:46:19 1987
Date-Received: Sun, 11-Oct-87 16:30:14 EDT
Organization: Princeton University, NJ
Lines: 38
Keywords: update on mitochondrail eve, big mama lives
Xref: mnetor sci.misc:534 sci.bio:709 soc.women:7649


In 1983 ther ewas a fairly extensive discussion of the above referenced
topic started by an article I posted which I reproduce, in part, below:

-All living people (or at least ~99% of them) have a single common female
-ancestor on their purely maternal line.  In other words, tracing back to
-one's mother's mother's mother's ... mother will bring everyone back to a
-single individual woman.  She is estimated to have lived between 50,000 and
-500,000 years ago.
-
-This result is based on comparisons of human mitochondrial DNA taken from
-very diverse populations all over the world.  Mitochondrial DNA is passed
-along solely (i.e., asexually) by females to their offspring.  The mutation
-rate for this process is very roughly known, and this together with delicate
-measurements of differences between two individuals' mitochondrial DNA, allows
-the determination of the interval since they shared a common pure female line
-ancestor.  The technique is fairly new and is not yet completely accepted, but
-so far no one has suggested any specific reason for doubting its validity.
-The most serious uncertainties are associated with the estimate of the time
-scale involved but do not alter the basic conclusion of a single common
-ancestor.
-
-Explanations for this "fact" are not as difficult as they might at first
-appear given reasonable assumptions about population and reproduction
-statistics; however, all such explanations imply that the human species
-must have once (before!) had a close brush with extinction.

If anyone is now or still interested, an update is given in the Research News
section of the Oct. 2 issue of SCIENCE (vol. 238, pp. 24-26).  The upshot is
that the basic result now seems to be generally accepted with the experts
falling to arguing about better dating estimates and detailed mechanisms.  It
remains true that the result suggests that our species has had at least one
rather close brush with extinction, direct or statistical.

Ed Turner			"Does one really have to fret
phoenix!elturner		 About enlightenment?
				 No matter what road I travel,
				 I'm going home."