GENEALOGY-DNA-L Archives

Archiver > GENEALOGY-DNA > 2006-10 > 1162352991


From: (John Chandler)
Subject: Re: [DNA] Neolithic J2 and E3b in Britain? Maybe not.
Date: Tue, 31 Oct 2006 22:49:51 -0500 (EST)
References: <02a701c6fd41$20655050$6401a8c0@Precision360>
In-Reply-To: <02a701c6fd41$20655050$6401a8c0@Precision360> (lgmayka@ieee.org)


Lawrence wrote:
> My understanding is that statistically, a lone man who travels to a faraway
> location is *very* unlikely to have exactly one, or just a few, male
> descendants two thousand years later. Most likely, his male line will die
> out, as most male lines do (except during a rapid expansion). Rarely (or
> during a rapid expansion), his line will succeed, and produce a multitude of
> male descendants whose yDNA will show their relationship. Can a
> statistician confirm or deny these probabilities?

In a static population, the extinction probability is virtually 100% --
but the population has been very far from static for the past two
thousand years. Also, the extinction probability is for *eventual*
extinction, not necessarily soon. Two thousand years is a short enough
time that a line "destined" for extinction might still be hanging on
with a few representatives.

Another important point to consider is that one lone man traveling
to a faraway place might well be followed by another migrant a few
decades or centuries later.

> Perhaps I should have stated the alternative hypothesis more clearly: That
> the small amounts of K2, E3b, J1, and I1b-Western and I1b-Isles are remnants
> of what were once much larger migrations. Through war, out-competition,
> etc., the newer haplogroups R1b, I1a, and R1a have become predominant only
> since the LGM.

The extinction argument works not only for isolated lines, but also for
tiny remnants of a once-large population. Once a group has nearly
vanished, it is ripe for complete disappearance -- eventually. Of
course, the group won't disappear after all if there are occasional
immigrants who "refresh" the population. In other words, it may be
very hard to tell for a *particular individual* whether his line is
a relative newcomer or an ancient holdover.

John Chandler

This thread: