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Archiver > GENEALOGY-DNA > 2011-12 > 1324586169


From: (John Chandler)
Subject: [DNA] Generations [was Re: King Tut's DNA- Youngest possible age ofP312]
Date: Thu, 22 Dec 2011 15:36:09 -0500
References: <1542418238.951585.1323629441687.JavaMail.root@sz0002a.westchester.pa.mail.comcast.net>
In-Reply-To: <1542418238.951585.1323629441687.JavaMail.root@sz0002a.westchester.pa.mail.comcast.net>(aklyosov@comcast.net)


Anatole wrote:
> Then, a generation is a "floating" number, which depends on many
> factors - cultures, habits, wars, cataclysms, diseases, etc. They vary
> in a wide range from at least 16 to at least 45, pick any number. A
> "generations" per se is a useless term to employ in historical
> calculations

You have put your finger precisely on the problem. As it happens, the
generation is the one-and-only relevant time unit in genetic
genealogy. The father-son studies have looked for, but failed to
establish, even a clear correlation between mutation likelihood and
father's age, let alone a linear relationship. In other words, the
intrinsic mutation process yields mutations per generation, not per
year. Therefore, trying to calibrate the mutation rate constants in
terms of years is to accept and propagate the huge uncertainty that
comes from that wide range in generation lengths.

John Chandler


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