Generally, only the popular press and Christians concerned with origins
take seriously the dates inferred by coalescent theory calculations with
regard to any actual individuals (i.e., an actual Eve or Adam). The dates
are estimates *given certain assumptions*. They are most useful when
compared to each other, as this can help to indicate histories of
short-term versus sustained bottlenecks, and modes of transmission, extent
of gene flow among geographical areas, etc.
Popular press versions of such study results should come with
disclaimer: "Any relation of these findings to actual individuals and
specific historical events are entirely speculative, albeit perhaps more
plausible than certain alternatives which are unambiguously falsified."
Doug
At 08:44 AM 11/1/00 -0500, you wrote:
>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
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