Due to my move last year and the mess up it caused in me receiving my
journals via the mails, I am just now getting the August 1999 Scientific
American. There is a fascinating article on the Out of
Africa/multiregionalism controversy entitled "Is Out of Africa Going Out
the door?" My interest in this concerns the growing evidence that there is
some genetic input from the archaic hominids into modern mankind. And if
they are our forefathers and mothers, then apologetically, we can't exclude
them from Adam's race. And contrary to the widespread preference so
recently expressed by David Siemens, that he "cannot push Adam and Noah
back millions of years." (2/10/00), their genetic continuity and
interbreeding with modern men makes it very difficult NOT to push Adam and
Noah back millions of years!
A couple of definitions of the out of Africa and multiregionalism are needed.
First the multiregionalism (sometimes called candelabra) as proposed in the
50s and 60s by Carleton Coon has been totally rejected by modern
anthropology. In that view, each local variety of homo sapiens evolved
independently from the local variety of archaic hominid. Modern views of
multiregionalism place tremendous emphasis upon gene flow across all
populations. Thus there was no independence to the evolution of the entire
population as a whole. This modification of the old multiregional view
allows each local population to be a mixture of local archaics and invading
Africans. It is akin to Gunter Brauer's Hybridize and Replacement theory.
(see Gunter Brauer, "The Evolution of Modern Humans: a Comparison of the
African and non-African Evidence," in Paul C. Mellars and Chris B. Stringer
ed. The Human Revolution. (Princeton: Princeton University Press, 1989),
pp. 123-153, p. 124) Thus, multiregionalism no longer means what it did in
the 60s when it garnered a very bad name for itself.
The Out of Africa theory is claimed to refute any gene flow from the
archaics to modern Homo sapiens. It is often claimed and thought by
non-anthropologists that the Africans came out of Africa and totally
replaced everyone with no interbreeding. This has not been the case with
the majority of anthropologists who advocate Out of Africa. Stringer,
Gamble and Tudge, who are Out of Africa proponents believe that there has
been some gene flow between us and the archaics. A sampling of
anthropological opinion follows:
"As we have already mentioned, there are occasional hints of interbreeding
between the two populations of hominids e.g., the bulging occipital bone of
one of the Cro-Magnon skulls, or the projecting mid-face of one of the
Moderns from Predmosti. We are not sure that such features do in fact
represent the result of interbreeding, but even assuming that they do, we
believe that such instances were exceptions, and that there was minimal
gene flow (interbreeding0 between the two populations." Christopher
Stringer and Clive Gamble, In Search of the Neanderthals, (New York: Thames
and Hudson, 1993), p. 193
**
Interbreeding
"Economic competition for the available resources would be the mechanism of
replacement of one population by another where there was coexistence,
perhaps coupled in some areas with a small degree of interbreeding (in
which e.g. a few Neanderthal genes would have been taken into the much
larger modern human gene pool)." Christopher Stringer and Clive Gamble, In
Search of the Neanderthals, (New York: Thames and Hudson, 1993), p. 72
**
Interbreeding
"The point is, though, that such breeding plans have given rise to a large
body of genetics theory--and this theory shows that the British and
European populations of Siberian tigers would effectively be genetically
continuous even if the flow of genes between them was remarkably small. In
other words, if just one European tiger per generation was brought to
Britain--or indeed just one in several generations--this would achieve all
the mixing required.
"Translate this into the experience of early hominids, from erectus
onwards: highly mobile, often adventurous, and marauding throughout Africa
and Eurasia. It seems inconceivable to me that newly arriving groups would
not have mated at least from time to time with peoples they met along the
way. Sometimes the contacts would have been friendly, sometimes forced.
But such things must surely have occurred, and if they did then there would
indeed have been gene flow between the many groups, precisely in the way
that Milford Wolpoff emphasizes. I still think the candelabra hypothesis is
wrong. But I also feel that we can reasonably impose considerable gene flow
on to the Out of Africa scenario. So in important details Wolpoff would
certainly be right. Modern human beings would indeed contain Neanderthal
genes." Colin Tudge, The Day Before Yesterday, (London: Pimlico, 1994), p. 237
**
Interbreeding
"The process of biological replacement was far more complex than mere
population movements, and probably involved slow assimilation and
hybridization of Neanderthal populations." Brian M. Fagan, The Journey from
Eden, (New York: Thames and Hudson, 1990), p. 49.
Now, given that background the article first attacks the issue of whether
or not mitochondrial DNA really proves what it is so often asserted, that
mankind is no older than 200,000 years and that there is no interbreeding.
Wong writes:
"The DNA from mitochondria, the cell's energy-producing organelles, has
been key Out of Africa evidence. Mitochondria are maternally inherited, so
genetic variation arises largely from mutation alone. And because mutations
have generally been though to occur randomly and to accumulate at a
constant rate, the date for the common mitochondrial DNA (mtDNA) ancestor
can theoretically be calculated. This 'molecular clock' indicates that the
mtDNA ancestor lived a mere 200,000 years ago, and the root of the gene
tree traces to Africa. These results, along with the observation that
variation is highest in Africa (indicating that modern humans had been in
Africa the longest), seemed to offer unambiguous support to a recent
African origin for all modern humans.
"But the significance of each finding has been questioned. The date is
suspect because he molecular clock depends on problematic assumptions, such
as the calibration date and as some studies suggest, then the rate of
mutation accumulation may have differed at different times. The African
root for the mtDNA gene tree is compatible with Out of Africa, but it does
not exclude Multiregionalism, which predicts that the common ancestor lived
somewhere in the Old World, probably Africa. And neither does the high
mtDNA variation in African populations as compared with non-Africans
uniquely support Out of Africa, according to anthropologist John H.
Relethford of the State University of New York College at Oneonta. 'You
could ge t the same result if Africa just had more people living there,
which makes sense ecologically,' he asserts." Kate Wong, 'Is Out of Africa
Going Out the Door?" Scientific American, Aug. 1999, p. 13-14
Wong quotes Alan Templeton, a leading geneticist as saying:
"Very few people try to look across all the systems to see the pattern," he
observes. Some nuclear genes indicate that archaic Asian populations
contributed to the modern human gene pool, and Templeton's own analyses of
multiple genetic systems reveal the genetic exchange between populations
predicted by Multiregionalism."
Templeton's technical work in this regard can be found at: Alan R.
Templeton, "Human Races: A Genetic and Evolutionary Perspective," American
Anthropologist, 100(1999):3:632-650.
Templeton in that work challenges the idea that mtDNA diversity can be
equated to age. Here is what he says and it is quite interesting:
"The danger of using diversity levels as an indicator of population age
from a bottleneck is illustrated by the observation that mitochondrial DNA
diversity within Africa is higher in food-producing populations than in
hunter-gatherers. By equating diversity to age, this result would imply
that agricultural peoples in Africa represent the ancestral populations,
whereas the hunter-gatherers are the recent descendant populations. Such a
conclusion is not credible, and the diversity levels within Africa are
interpreted as reflecting effective size differences." Alan R. Templeton,
"Human Races: A Genetic and Evolutionary Perspective," American
Anthropologist, 100(1999):3:632-650,, p.637
After discussing the mtDNA evidence, Wong then discusses the evidence from
the bones. Wong writes:
"But those who believe that Out of Africa's genetic fortress is
crumbling find confirmation in fresh fossil data that pose new difficulties
for the theory's bony underpinnings. Last December researchers unearthed in
western Portugal's Lapedo Valley a fossil that preserves in exquisite
detail the skeleton of a four-year-old child buried some 24,000 years ago.
According to Erik Trinkaus, a Washington University paleoanthropologist who
examined the specimen, the team fully expected the remains to represent a
modern human, based on its date and the style of the burial. But subsequent
analysis, published in the June 22 Proceedings of the National Academy of
Sciences USA, revealed a surprising combination of features, such as a
modern-looking chin and Neanderthal limb proportions. After reviewing
scientific literature on primate hybrids, Trinkaus concluded that this
child resulted from interbreeding between Neanderthals and modern humans."
"Not everyone is persuaded. Christopher B. Stringer of London's
Natural History Museum, lead proponent of the Out of Africa model, wonders
whether the fossil might simply represent a cold-adapted modern human,
because Portugal then was colder than it is today. In any case, Stringer
maintains that his model does not exclude occasional interbreeding." Kate
Wong, 'Is Out of Africa Going Out the Door?" Scientific American, Aug.
1999, p. 14
And given the new dating of the Mungo remains, which I reported on last
year, Wong relates:
"Multiregionalism also best explains the surprising new date for a
previously known fossil from western New South Wales, according to
paleoanthropologist Alan Thorne of the Australian National University. In
the June Journal of Human Evolution Thorne and his colleagues report that
the fossil, known as Lake Mungo 3, now looks to be some 60,000 years
old--nearly twice as old as previously thought--and unlike the other early
Australian remains (all of which date to less than 20,000 years ago), this
one bears delicate, modern features. To Stringer, this gracile form
indicates the arrival of modern humans from Africa, albeit an early one.
Over time, he reasons, selection could have led to the robust morphology
seen 40,000 years later."
"But Thorne argues that such dramatic change is unlikely over such
a short period and that fossils from the only environmentally comparable
region--southern Africa--show that people have remained gracile over the
past 100,000 years. Moreover, Thorne maintains, "there is nothing in the
evidence from Australia which says Africa"--not even the Mungo fossil's
modern features, which he believes look much more like those of
contemporaneous Chinese fossils. And Thorne observes that living indigenous
Australians share a special suite of skeletal and dental features with
humans who inhabited Indonesia at least 100,000 years ago."
"Therefore, he offers, a simpler explanation is that the two
populations arrived in Australia at different times--one from China and the
other from Indonesia--and mixed, much like what has been proposed for
Neanderthals and moderns in Europe. " Kate Wong, 'Is Out of Africa Going
Out the Door?" Scientific American, Aug. 1999, p. 14
The entire article can be found at:
http://www.scientificamerican.com/1999/0899issue/0899infocus.html
glenn
Foundation, Fall and Flood
Adam, Apes and Anthropology
http://www.flash.net/~mortongr/dmd.htm
Lots of information on creation/evolution
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