GENEALOGY-DNA-L Archives

Archiver > GENEALOGY-DNA > 2005-08 > 1123181868


From: (John Chandler)
Subject: Re: [DNA] SNP mutation rates
Date: Thu, 4 Aug 2005 14:57:48 -0400 (EDT)
References: <IGEOKAGLHNEKPCKPADIGOEIKKEAA.bbailey.lowedna@baileyconnection.com> <REME20050803190044@alum.mit.edu> <090b01c59884$6238c5c0$0200a8c0@c452380a> <REME20050803194536@alum.mit.edu> <097001c59905$fff2b6f0$0200a8c0@c452380a>
In-Reply-To: <097001c59905$fff2b6f0$0200a8c0@c452380a> (ecbeaty@comcast.net)


Earl wrote:
> That raises another point where my intuition is in conflict with accepted
> reality. Way back in time some guy was born with the M207 mutation, starting
> haplogroup R, and making him different from all the thousands of other men
> living at the time. Somehow his male-line descendants came to dominate
> Europe, and all (almost) the others died out. It is easy to understand how
> the M207 guy has more male-line descendants than his brothers. The problem
> is the SIZE of the disparity. The result seems so overwhelmingly improbable.

The main point to consider is that the population size is extremely
unstable. The unchecked growth rate is huge, and the attrition rate
is almost as big. Don't forget that, on top of all the hazards in
life, there is also the possibility of passing on the X chromosome
instead of the Y, i.e., many offspring but no sons. The result of
all this is a very high probability that any specific man's Y
chromosome will go extinct, but any line that survives is likely
to expand enormously. To put it another way, the only sure way
to avoid extinction is to become predominant.

John Chandler

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