Due to some transatlanic holdup the 5 Nov digest only reached me after 6
days! Thus this response may be rather belated, I hope it is still
relevant.
On Tue, 4 Nov 1997 Loren Cordain <[log in to unmask]> wrote:
>
> Dick Bird's questioned the evidence regarding differences between modern
> man's genome and that of paleolithic man. Clearly, the suggestion that
> there are minimal differences can only be inferred. The amount of
> mitochondrial DNA diversity in various human racial groups from around
> the world has been determined (1), additionally the rate of
> mitochondrial DNA change can also be estimated (1,2). Based upon this
> rate of mDNA change, as well as similar nuclear DNA studies (3), the
> genetic differences between humans living 40,000 yrs ago and those
> living today ago can be estimated. A similar approach has been used
> to determine if Neanderthals were precursors to modern humans or were
> separate species (4).
But all these studies have been conducted on what are believed to be
non-coding unselected parts of the genome, and cannot be extrapolated to
rates of change in parts of the genome which are under selection. A
stronger argument can be built from the following facts:
a) mtDNA and nuclear DNA evidence shows that there has been a recent
(100-200ka ago) population bottleneck follwed by rapid expansion, which
explains the lack of genetic diversity amongst modern humans, and:
b) a conservative reading of the archaeological evidence shows that modern
human populations were present throughout the Old World by 40ka
Thus given our species recent origin, and geographical dispersion, we can
argue that there will be no nutritional selective pressures common to all
Homo sapiens. The nutritional niche for which we are selected will either
be that of the founding population, or more or less modified versions of
it, varying between regions. So there may be entire populations or large
proportions of populations with genetic adaptations to local food
resources.
As Loren says, we observe some of these:
> there are a number of genotypic differences among various human
> populations that are known to have been elicited by diet (i.e. adult
> lactase persistence and a variety of hemoglobinopathies, and perhaps the
> degree of insulin resistance/sensitivity) since the agricultural
> revolution. Consequently, modern human genomes (particularly in those
> populations with the greatest exposure to agriculture) are not identical
> to our paleolithic ancestors, and some of these slight genetic
> differences may have important health ramifications for modern man.
BUT these are minor variations:
> All humans require similar ranges of both macro and micronutrients and
> all human groups have similar anatomical, physiological and endocrine
> functions in regard to diet and nutrition.
we therefore may conclude that:
> The reason for these similarities is because of our common evolutionary
> experience - we were all hunter gatherers dependent upon wild plants and
> animals - and these dietary selective pressures shaped our present day
> nutritional requirements.
When in the past should we look for this palaeolithic diet which is the
common inheritance of all humans? It must be before the population
dispersal which allowed regionally varying diets to arise. We cannot then
look at Upper Palaeolithic diets, as they are certainly after the
dispersal. Accepting the genetic evidence for a bottleneck mentioned
above leads us acceptance an Out Of Africa II scenario rather than a
Multiregional Evolution scenario for the origin of modern humans, and thus
to place the dispersal event of interest at c.120-100ka. Therefore it is
amongst archaic Homo sapiens and possibly late Homo erectus *in Africa*
that we should seek this diet, and probably in some smaller (but as yet
undefined) part of Africa.
Andrew
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Dr. Andrew Millard [log in to unmask]
Department of Archaeology, University of Durham, Tel: +44 191 374 4757
South Road, Durham. DH1 3LE. United Kingdom. Fax: +44 191 374 3619
http://www.dur.ac.uk/~drk0arm/
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