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From: "Ken Nordtvedt" <>
Subject: [DNA] 40 Nodes to You
Date: Mon, 7 Sep 2009 09:29:29 -0600


I mentioned that each of us males will probably be able to uniquely map our ancestral line back to genetic Adam with 50 node choices in the y tree. 50 was a generous estimate, I really think the number is more like 40 nodes.

I am I1-ASgeneric. I counted just 8 nodes in the y tree between genetic Adam and the I1-AS MRCA. That covers the time from maybe 70,000 years ago to 4000 years ago.

That leaves me about 32 more nodes to get from I1 MRCA living 4000 years ago to the present. But the y tree is really bushy along those last 4000 years of my line, so the nodes will certainly be close together and 32 of them could certainly be required to reach me. If you sketch a realistic y tree or just imagine it, note how bushy it is the last few thousand years and pruned down to hefty limbs further back in time. That's because of the population explosion that came with the newer ways of life of agriculture, technology, industrialization, etc.

Let's return to those first 8 nodes in my ancestral line from genetic Adam which are already identified. Suppose each node was perfectly efficient in dividing the male population of the world in half. 1/2 raised to the 8th power is 256. 3 billion males in today's world divided by 256 is about 12 million. I believe the number of I1 males today probably exceeds 12 million, but not by a huge multiple. So I1 can be said to be slightly more demographically successful than average of today's "8th degree" haplogroups in the world.

Ken


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