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Archiver > GENBRIT > 2006-01 > 1137427256


From: Doug McDonald <>
Subject: Re: Most recent common ancestors
Date: Mon, 16 Jan 2006 10:00:56 -0600
References: <1137338990.456458.231910@f14g2000cwb.googlegroups.com> <mo4ms15t5bs77ev0ds8bhs690882gdmb15@4ax.com>
In-Reply-To: <mo4ms15t5bs77ev0ds8bhs690882gdmb15@4ax.com>


Denis Beauregard wrote:
> On 15 Jan 2006 07:29:50 -0800, wrote in
> soc.genealogy.medieval:
>
>
>>(Also published at http://www.livejournal.com/users/nhw/563512.html )
>>
>>Doug Rohde's paper on the most recent common ancestor of all humanity
>>(http://tedlab.mit.edu/~dr/Papers/Rohde-MRCA-two.pdf) is, I think, well
>>known to most here. ... Rohde's computer
>>simulations gave results of between 3,000 and 5,000 years ago for the
>>lifetime of the most recent common ancestor of all humanity.
>
>
> Must be junk ! If you check artefacts from 3000 years ago, you will
> see that "racial" features were already defined at that time, i.e.
> color of skin or shape of eyes.

This is immaterial. The amount of mixing proposed by Rhode is
so tiny that no obvious feature would be visible. In fact, it is
so small that in many people today there would not even be any
DNA derived from the common ancestor, even though they descnd from him.



>Since these features survived because
> of separated cultures (i.e. in a world where there is no racism, I
> think those differences are vanishing after many interracial
> weddings). So, if those features already existed 3000 years ago, how
> can you explain the common ancestors are so late.

Rhode proposes only a teensy bit of mixing.


>
> Moreover, Americas were isolated from Asia at least 15,000 years ago.

No, not at all. There has always been some communication across
the Bering Strait. In fact, there is a substantial DNA
component in Siberia that CLEARLY comes from America. The
communication surely went in both directions.

>
> We don't need that kind of pseudo-science... The model is obviously
> wrong.
>

It's not wrong. It just may be miscalibrated.

Doug McDonald
>
> Denis
>

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