Archiver > GENEALOGY-DNA > 2010-03 > 1268630504

From: "Ken Nordtvedt" <>
Subject: Re: [DNA] Clades, Definitions, Discoveries, FTDNA
Date: Sun, 14 Mar 2010 23:21:47 -0600
References: <>,<SNT115-W100A5F4E30C0231B9E890ACC2E0@phx.gbl>,<016301cac3e3$fe0b33e0$5e82af48@Ken1><SNT115-W196CFB24CCDD653D7C3D50CC2E0@phx.gbl><01ba01cac3fb$87b368d0$5e82af48@Ken1>

I just dropped a "million" from my comment. For those just tuning in.
Correction is below

----- Original Message -----
From: "Ken Nordtvedt" <>
To: <>
Sent: Sunday, March 14, 2010 10:53 PM
Subject: Re: [DNA] Clades, Definitions, Discoveries, FTDNA

> ----- Original Message -----
> From: "Steven Bird" <>
>> Let's do the numbers:
> [[That's sure welcome; some one around here who wants to do the numbers ]]
>> There were 134 million births last year, according to the U.N. estimates.
>> Half of these were boys, so about 67 million boys. The odds of a SNP
>> occurring, according to Hartwell 2008, are 1 in a billion. That means
>> that there is just a 6.7% chance of a Y-SNP occurring within ONE birth
>> among those 67 million boys last year. Following your logic, on average,
>> ONE new SNP occurs among all births every 15 years or so. However, since
>> the new SNP is always de novo and can occur anywhere, and there are 3
>> billion base pairs in the human genome, the odds of any one SNP being
>> duplicated are 3.0 * 10 to the -17 power.
> [[ For purposes of the Y tree we are only interested in the mutations at
> base pairs on the y chromosome. I'll take 25 million base pairs in the y
> as
> the practical region.
> 67 million males were born last year. EACH base pair on the y has your
> one in a
> billion chance of mutating. So EACH base pair had a .067 chance of
> mutating
> last year. So EACH base pair had a chance of approximately ONE to mutate
> over about 16 years. That's half a generation --- so in half a generation
> EACH and every practical snp site on the y chromosome has on average
> mutated
> once. I still don't know why you are bringing the 3 billion base pairs of
> the whole genome into the picture. The snps used for the male y tree are
> only from the y chromosome. Ken ]]
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