Ruediger asked, "The difference between us and our last African
ancestor cannot exceed the differences between modern Europeans and
Africans. Isnt there still an African gut under our fair skin"?
Back in November 1997 there was an interesting post on this issue
by Andrew Millard. For those new to this list, I attach it below
(the comments that Andrew responds to are by Loren Cordain).
At the time, there was no response to Andrew's point.
One implication that I get from it is that the diet subsistence
pattern of 20th C HGers living in environments similar to those
of the Lower Paleolithic African populations that Andrew refers to
might be a better guide to the pattern that modern humans are adapted
for than an average over 20th C HG groups scattered across a variety
of environments (these 20th C groups might better reflect diet
patterns of Upper Paleolithic humans -- post Out of Africa II).
Steve Meyers
----------------------------------------------------
Date: Tue, 11 Nov 1997 16:38:51 +0000
From: Andrew Millard <[log in to unmask]>
COMMON ANCESTRAL DIET
> Dick Bird 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 Paleolithic 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.
>I asked: Why do you only go as far back as late Homo erectus?
Essentially I was arguing when our *most recent* common ancestral diet
was, which is clearly that of archaic Homo sapiens in Africa. Homo
erectus is another species, although ancestral, and therefore more removed
from us. The late African Homo erectus (sensu lato) were presumably
moving towards being like modern humans, but the further back you go, the
more likely it is that the diet was different, particularly given the
glacial-interglacial cycles occurring at the time of H.s. arising from
H.e. IT IS QUITE POSSIBLE THAT THE SPECIATION INVOLVED A DIETARY SHIFT.
HENCE i WOULD PREFER TO LOOK AT OUR OWN SPECIES IF POSSIBLE, and if not
then the most closely related part of another species.
Of course if you take the regional continuity hypothesis, then the common
ancestral diet is that of early H.e., but, given the apparently rapid
spread of that species around the world, the best we can do might be to
look at late H. habilis.
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
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