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Archiver > GENEALOGY-DNA > 2005-07 > 1121876010


From: Bonnie Schrack <>
Subject: Re: recent common ancestry of everyone
Date: Wed, 20 Jul 2005 12:13:30 -0400


So, what's wrong with this picture? I think their conclusions must
greatly underestimate the degree of consanguinity (inbreeding) in most
populations, and the well-known consequence, pedigree collapse. Because
of this most people have far fewer ancestors than they would otherwise.
The theory at hand says that our number of ancestors becomes
astronomical in a short time, and therefore overlaps to a great degree
and very quickly, with all other living humans. Related to the way they
ignore consanguinity is that there was far more local isolation, I
think, than they seem to taking account of.

The people involved seem to be highly qualified in math and "cognitive
sciences," but they have no authors involved who would have given them a
reality check from fields such as history and anthropology, much les
genealogy. The results of math and computer simulation can be only as
good as the accuracy of the premises they are based on.

I have a neat book that I found at the U. of MD library, by L. Luca
Cavalli-Sforza et al: Consanguinity, Inbreeding, and Genetic Drift in
Italy (2004). It's an amazing book, making use of massive volumes of
genealogical data obtained from Catholic Church records, and it
demonstrates the huge prevalence of closely consanguineous marriages
that have taken place over many generations. Hopefully with time, this
kind of information will be taken into account by those constructing
such theories as Rohde's. I did a search, and the words "consanguinity"
and "inbreeding" don't even appear in the article.

Bonnie Schrack


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