Archiver > GENEALOGY-DNA > 2006-08 > 1154486837

Subject: Re: [DNA] research strategy for genealogists
Date: Tue, 1 Aug 2006 22:47:17 EDT

In a message dated 7/31/2006 2:30:52 PM Pacific Daylight Time,

> The difference between animal morphology and Y-chromosome STRs is that the
> former is being driven by natural selection, while we are assuming the
> latter is
> selection neutral, meaning the resemblances are technically coincidence, not
> convergence. So, how does "resemblance" caused by coincidence or
> convergence
> affect our Y-DNA STR research strategy? Is having two unrelated animals
> look
> alike similar to having similar STR motifs? The answer is, yes, in terms of
> having to figure out how to separate real relationship from a superficial
> resemblance.

It is surprisingly difficult to achieve this state of
coincidence/convergence. I know you meant it to dramatize your point, but your specific example would
be well nigh impossible to achieve. I ran some simulations one time with
easier starting points -- just one or two differences out of 37 markers. The
results were summarized in this old message (long URL, ends in +F)

Convergence occurred in a very small percentage of cases, so it's not a good
explanation for why different surnames have the same haplotype. Relatively
speaking (pun!), it's far more likely that they have the same haplotype because
they descend from a common ancestor who lived before the time surnames were
adopted. It's harder to estimate the relative probability of another explanation,
that different surnames have the same haplotype because of name changes and
misattributed paternity in more recent times, where there's some chance of
finding a paper trail.

Ann Turner

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