Hi, Glenn
An important caveat. All these estimates are based on coalescent theory,
which is a very successful area within population genetics. CT basically
deals with phylogenies of different alleles in the same species, and uses
those phylogenies to estimate things such as most recent common ancestors,
effective population sizes and measures of gene flow. One of the most
common assumptions is that the genes must be selectively neutral or at
least nearly neutral. Any strongly beneficial mutation in the y chromosome
could increase the frequency of that allele as well as other linked genes
("a selective sweep"). As a consequence, the estimated time for the most
recent common ancestor would be biased towards the present, which could be
the case here.
On the other hand, calculations by Francisco Ayala using the same
coalescent theory suggested that the human effective population size
(number of reproductively active individuals in a population) never became
smaller than 50 individuals since the divergence from chimps. This is
inconsistent with the idea of a very strong populational bottleneck with
only one active female.
Marcio
At 06:45 AM 11/1/00 +0000, glenn morton wrote:
>There was a fascinating article in The Times yesterday in which genetics is
>showing that the y-chromosome Adam never met the mtDNA Eve. Adam leved about
>59,000 years ago and Eve 143,000. Now, if one wants to maintain any sort of
>Biblical historicity in the face of this kind of data, one needs to either
>move Adam and Eve back to a time prior to 143,000 years ago (as I suggest)
>or have Adam and Eve NOT be the parents of all people (as Dick Fischer
>advocates). One simply can't have the data-ignoring position of Hugh Ross
>who would say that Adam and Eve were created sometime after 60,000 years
>ago. Genetics simply doesn't allow that possibility any more. Here is part
>of the article.
>
>http://www.thetimes.co.uk/article/0,,27713,00.html
>Tuesday October 31,2000
>
>Even early man was late for first date
>
>BY NIGEL HAWKES HEALTH EDITOR
>
>"WOMEN were the complete article long before men, a new study has shown.
>
>Geneticists have found that female genes acquired their modern form 143,000
>years ago but the male version was not up and running for another 84,000
>years.
>
>The result overturns the Biblical description of women being created from a
>spare rib left over from a man, and suggests that if Eve ever did meet Adam
>she was slumming it, genetically speaking.
>
>*The result overturns the Biblical description of women being created from a
>spare rib left over from a man*, and suggests that if Eve ever did meet Adam
>she was slumming it, genetically speaking.
>
>An international team led by Peter Underhill of Stanford University studied
>the Y chromosome, which confers maleness, of more than 1,000 men from 22
>parts of the world. By creating a family tree of genetic variations, it is
>possible to trace it back to a putative ancestor from whom all varieties of
>today's Y chromosome originated.
>Similar studies have been made of mitochondrial DNA, which is passed down
>unchanged through the maternal line. These studies have shown that we are
>all ultimately descended from an "ancestral Eve" who lived in Africa about
>143,000 years ago.
>
>But ancestral Adam, measured by the Y chromosome clock, was alive a mere
>59,000 years ago. So it is clear than ancestral Eve never met ancestral
>Adam, though she must have met some sort of male in order to have begotten
>all those descendants. Dr Underhill and his team report in Nature Genetics
>that the perfect DNA for men simply took longer to emerge. There must have
>been thousands of generations of men whose maleness was provided by
>different, less perfect, versions of the Y chromosome.
>
>
>glenn
>
>see http://www.flash.net/~mortongr/dmd.htm
>for lots of creation/evolution information
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Marcio R. Pie
Department of Biology
Boston University
5 Cummington St.
Boston, MA 02215
Phone: (617) 353-6974
FAX: (617) 353-6340
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