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Re: puzzle of the negrito: isolated archaic populations
Edward Green (erg@panix.com)
5 Dec 1996 19:28:41 -0500
Gerold Firl <geroldf@sdd.hp.com> wrote:
I find the idea of remnant populations fascinating for some reason --
thanks for posting the interesting article.
Haven't the British isles been colonized by four or five known waves,
fading off into prehistory, each subsequent wave driving the
predecessors north and east into the less hospitable, or at least
less centrally located parts if the islands? You suggest something
similar with the negrito populations, though perhaps on larger
geographic and temporal scales.
>Remnant populations of small, frizzy-haired, forest-dwelling peoples
>still exist (or did within the last century) in isolated pockets
>throughout asia, from the phillipines, malaysia, indonesia, the
>andaman islands, and possibly india as well. Average height for men
>ranged from around 4 1/2 feet to just under 5, leading to the name
>"negrito", and begging the question of relations to the african
>pygmies. How did the negritos come to be? The answer to this question
>could have important implications for the history of human evolution.
Except for height, the Australian aboriginies seem physically
similar? Just a thought.
>The african pygmies are the best example we have of human adaptation
>for a specialized environment. The equatorial african rainforest,
>existing throughout multiple cycles of glacial advance and retreat,
>presents special problems of survival and adaptation. All the
>rainforest species are smaller than their savanna ancestors; one
>antelope is the size of a rabbit. The human inhabitants of the forest
>have adapted in similar directions; pygmy scale is well suited to the
>heat, humidity, and dense growth.
>
>The origin of the pygmies seems fairly obvious: they have evolved to
>live in the forest, which has remained a stable environment
>throughout the climatic fluctuations of the last few million years. It
>isn't known how long the forest has been their home; the rainforest
>has not yielded any fossil clues as of yet, and conditions are not
>good for bone preservation. But what of the negritos? How did they
>settle their far-flung range?
>
>One possibility is that the negrito evolved, in-situ, just as did
>their african counterparts. If we knew how long it took for the
>african pygmy adaptation to evolve, that would provide a useful
>comparison for the candleabra hypothesis.
>
>Another possibility is that the negrito are the direct descendants of
>african pygmies.
Or just to be perfectly nit-picking, a common pygmie like ancestor.
>The out-of-africa scenario would seem to require a
>climatic epoch where tropical forests covered the intervening arid
>territory between equatorial africa and india; have such conditions
>ever existed?
Ok, here I may have something intelligent to say.
First, it seems to me another possibility is that the negrito like
people were previously endemic, without therefore being "out of
Africa". Well, accepting Africa as the cradle of humanity, their
ancestors were out of Africa at some point, but there may have been
an intervening epoch when large tracts of contiguous rain forest
communicating with the African rain forest supported a dispersed and
stable population negrito peoples, the shrinking and fragmenting of
the rain forest coming later, and with it the fragmenting of the
negrito population.
Further, I wonder if you have considered that while they may be
adapted to the rain forest, they may not be obligate dwellers in the
rain forest. That is, if conditions for migration were otherwise
favorable, I don't see why migrating bands may not have covered
relatively inhospitable intervening territory -- maybe even settled
there, but been driven out later by better adapted human variants.
>A number of factors lend support to the out-of-africa hypothesis, none
>of them conclusive; first of all, the negrito *look* african.
Hmm... this seems dangerous. Perhaps you mean some skelatal
characteritics evolve more slowly than skin pigmentation, and there
fore might show common ancestory longer -- like the dark skinned
people of southern India, who have European (if that is the right
word) facial structure? I guess the question is, do the "look"
African in ways that are not-adaptive, and therefore not likely to
indicate convergent evolution, but rather common ancestory.
>Their
>skin color is light by african standards (though pygmy skin color is
>also lighter than their bantu neighbors), but the rest of their
>physiology appears african. An interesting detail is the fact that the
>negrito *sit* like pygmies, with their legs stretched out straight in
>front of them; I know of no other people who sit that way. The socio-
>economic relationship between the negrito and their neighbors is
>strikingly analogous to that found in africa: the negrito trade meat,
>honey, and other forest products for agricultural and manufactured
>products from the villages. In common with the pygmies, the negrito do
>not build a fixed abode, and they also have largely abandoned their
>native language to adopt the speech of their neighbors.
>
>The relic populations of vedda peoples found in indonesia, sri lanka,
>and arabia felix provide another analogy; it seems unlikely that both
>races co-evolved in-situ. One, if not both, must have arrived as part
>of a great migration.
>
>Keep in mind that asia has been occupied by hominids for at least a
>million years, and throughout that time the 100,000 year glacial cycle
>has repeatedly exposed and inundated the continental shelves, shifting
>ecological zones southwards as the glaciers expanded, and then back
>north during the interglacials. If, during one of the interglacials,
>rainforest managed to extend around the horn of africa, up into
>arabia, and around the persian gulf through the indus valley, then the
>puzzle of the negrito may be solved.
I have heard that the great deserts in that part of the world are
products of human intervention in the environment. This may be
germane. Again, thank you for a fascinating post -- I could not
bring myself to cut the quotes.
Ed Green
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