Genealogists will readily admit to
an insatiable curiosity about their ancestors. Fitting one new ancestor onto a
pedigree chart provides only a temporary moment of triumph. It immediately
raises two more questions – who were the father and mother?
The same applies to tracing DNA
patterns. We rejoice when we find a DNA cousin in one ancestral line, but our
curiosity will not be completely satisfied until the complete genome of
everyone on earth has been linked into one gigantic network, showing how we are
all cousins many times over.
Yet if we take Rudyard Kipling’s
phrase, ‘satiable curiosity, in a literal way, there are many questions that
might be addressed with small-scale projects, perhaps even by students taking a
class on DNA analysis techniques. The genetic genealogy community could provide
samples that have already been analyzed to some extent, and the students could
end up with a publishable paper.
For example, the Y-chromosome
phylogenetic tree has been cobbled together using markers developed at
different laboratories (see
http://ycc.biosci.arizona.edu/nomenclature_system/frontpage.html). Some
branches of the tree have two or even more markers, which are “phylogenetically equivalent” – that is, no cases have yet
been found where one marker is positive and the other marker is negative. Yet
not all papers actually report on both markers, and the number of samples may
be quite small.
Take the fragment of the tree shown
in Figure 1. We see that the markers P36, M242, and MEH2 appear on the main
branch point leading to Haplogroup Q. The researchers could put out a call to
the genetic genealogy community for people who have been proven, or even
predicted, to belong to Haplogroup Q. These could all be typed for both markers
to see whether they all still hang together, or if they actually define two
distinct branches. Similar experiments could be performed at other points on
the phylogenetic tree.
Figure
1 Fragment of the Y-Chromosome Phylogenetic Tree
The genetic genealogy community is
an untapped resource of willing volunteers who have been prescreened by
commercially available testing procedures. Future editions of this column will
include requests from researchers looking for subjects as well as questions
posed by genealogists. Please send submissions to Ann Turner at the address
below, with the subject line “Satiable Curiosity.”
Ann Turner