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Archiver > GENEALOGY-DNA > 2010-07 > 1280130829


From: "Clay Daniels" <>
Subject: Re: [DNA] Bottlenecks not needed
Date: Mon, 26 Jul 2010 02:53:49 -0500


Please disregard my message. I got P312 amd P 314 confused.

Sorry

Clay
----- Original Message -----
From: "Clay Daniels" <>
To: <>
Sent: Monday, July 26, 2010 2:43 AM
Subject: Re: [DNA] Bottlenecks not needed


> John, my mouth is agape. You seemed to have nailed it. So if I'm L21+ but
> P312-, do we assume about 18,000 years back to L21?
>
> Clay
> ----- Original Message -----
> From: "Alister John Marsh" <>
> To: <>
> Sent: Sunday, July 25, 2010 8:30 PM
> Subject: Re: [DNA] Bottlenecks not needed
>
>
>> Ken,
>>
>> You suggest Y-Adam lived about 72,000 years ago. I have a poor memory
>> for
>> dates, but I think the Toba eruption was about about 72,000 years ago. I
>> believe they found human stone tools outside of Africa before the Toba
>> ash
>> layer, and near the same locations found very similar human stone tools
>> relatively soon after the Toba ash layer, so some human lines outside of
>> Africa seemed to have survived Toba. Toba is speculated to be an event
>> which prompted a significant environmental change which likely caused a
>> bottleneck of some significance. Based on that, I think there is
>> moderately
>> good evidence that Y-DNA Adam was before 72,000 years ago, and European
>> lines leading to F, I J, K P were living outside of Africa before Toba..
>>
>> Looking at the historic CO2 and temperature levels, a long cool period
>> ended
>> about 140,000 years ago and from then temperatures rose steadily until
>> about
>> 128,000 years ago. Currently we have an historically high temperature
>> range, and human population is mushrooming. I think one of the steady
>> temperature rising periods is the most likely time for population growth.
>> Although as I recently said, there could be a lot of different scenarios,
>> I
>> think the expansion from Y-Adam was likely between 140,000 years ago and
>> 128,000 years ago. My "guess" is that the line from Y-Adam branched
>> closer
>> to 140,000 years ago than 130,000 years ago. In view of the difficulty
>> of
>> guessing, in round numbers to the nearest 10,000 years, I would say
>> Y-Adam
>> had 2 surviving male lines "approximately" 140,000 years ago.
>>
>> In the article which started this thread, one study suggested a
>> bottleneck
>> in Africa between 183,000 and 123 years ago. Myself, I think this is a
>> plausible time for Y-Adam to have lived.
>>
>> I think your 72,000 year ago estimate for Adam may be about 50% too
>> short.
>>
>> Given the scale of the Toba event, it probably affected Y-DNA lines
>> globally. If Y-Adam hypothetically lived 140,000 years ago, there should
>> be
>> a noticeable bottleneck half way since then, evidenced by a branching of
>> haplogroup lines subsequent to 72,000 years ago, but with a major
>> branching
>> event since about 18,000 years ago as we came out of the last ice age.
>> We
>> can count the SNPs occurring an all haplogroups since Adam.
>>
>> Looking at the Y-Tree at http://ytree.ftdna.com/ , there are 84 SNPs in
>> the
>> line from Y-Adam to R1b1b2a1a2- P312. A quick count of SNPs is as
>> follows
>> (numbers are undivided runs of SNPs)...
>>
>> Y-Adam <<< perhaps 140,000 years ago????
>> 2 (SNPs) ends in A
>> 5 ends in BT/BR
>> 3 ends in CT
>> 1 ends in CF
>> 26 ends in F <<< end of significant bottleneck
>> 2 ends in IJK
>> 4 end in K
>> 21 ends in P <<< end of significant bottleneck
>> 8 ends in R <<< end of significant bottleneck
>> 1 ends in R1b
>> 3 ends in R1b1
>> 1
>> 1
>> 1
>> 2
>> 3 ends in R1b1b2a1a2 (P312) <<< perhaps 5,000 years ago???
>>
>> Let's for arguments sake, say Y-Adam lived 140,000 years ago, and P312
>> lived
>> 5,000 years ago. That is 135,000 years with 84 SNPs, or roughly 1607
>> years
>> per discovered Y-SNP on this line.
>>
>> A very significant bottleneck started after K (43 SNPs since Y Adam) ,
>> and
>> ended with P (64 SNPs from Y-Adam), . If Y-Adam was 140,000 years ago,
>> and
>> 43 SNPs to K represent 43x1607= 69,100 years, then K might have lived
>> 71,000
>> years ago. When was the major Toba eruption, 72,000 years ago?
>>
>> Ok, suppose K lived 1,000 years after Toba when there may have been a
>> following long lean period for humans, the line to P has 21 undivided
>> SNPs
>> from K. That could be roughly assessed at 21x1607= 33,700 years, or
>> about
>> 37,300 years ago. There was another longish bottleneck after P which
>> ended
>> in R, after 8 SNPs. 8x1607= 12,800, so perhaps R dates to 24,500 years
>> ago.
>> Now 24,500 years ago is almost exactly the date when global temperatures
>> reached the lowest level in the past million or so years, and from there
>> started rising to where we are today. I suggest rising temperatures
>> favoured humans and their food sources.
>>
>> If we move on 4 SNPs since R, we get to R1b1, which 4x1607= 6,400 years,
>> suggests R1b1 lived about 18,100 years ago. Although the temperatures
>> bottomed out at about 24,000 years ago, there was a little stutter in the
>> temperature rise at about 18,000 years ago, and since then there was a
>> very
>> rapid steady rise in temperature similar to that occurring about 140,000
>> years ago..
>>
>> Now I have only looked at the line to P312. I am assuming it has been a
>> well researched line, so the SNP trail along that line is probably as
>> good
>> as we will get in any haplogroup.
>>
>> Looking only at temperature and CO2 levels, the two most significant
>> dates
>> by far would be about 140,000 years ago and 18,000 years ago, when at
>> those
>> two dates temperatures set off from notable lows and headed "very
>> rapidly"
>> on 10 degree plus rises over the next 10,000 or so years. I suggest
>> that
>> Y-Adam lived approximately 140,000 years ago correlating with the start
>> of a
>> very rapid large rise in temperature. I suggest R lived about 24,000
>> years
>> ago correlating with the start of the temperature rise from the million
>> year
>> low, and R1b1 lived about 18,000 years ago correlating with the start of
>> a
>> very steady uninterrupted temperature rise very similar to that occurring
>> at
>> the time I speculate for Y-Adam.
>>
>> I think with this proposal, the start about 71,000 years ago of the very
>> significant bottleneck ending in P, is an interesting correlation with
>> Toba
>> at about 72,000 years ago. However, if you were to set the date for
>> Y-Adam
>> at 72,000 years ago, it is possible that key bottleneck events would
>> correlate with some temperature events. So my correlation attempt is not
>> the only interpretation.
>>
>> Just my view, based on assumptions of roughly uniform distribution of
>> SNPs,
>> and assumed reference points of 140,000 years ago since Y Adam, and 5,000
>> years ago since P312.
>>
>> John.
>

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