Re: puzzle of the negrito: isolated archaic populations
Gerold Firl (geroldf@sdd.hp.com)
6 Dec 1996 22:05:37 GMT
In article <587pbp$4ek@panix2.panix.com>, erg@panix.com (Edward Green) writes:
|> Gerold Firl <geroldf@sdd.hp.com> wrote:
|> 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.
Right. And since austronesia is at the end of the line, in terms of
migrations from the evolutionary hot-spots of africa and eurasia, and
is only accessible to non-seafaring peoples during glacial episodes
when sea level is very low, we also get more population variability.
The indonesian islands have an amazing variety of peoples, including
SE asian, negrito, melanesian, and the caucasoid vedda. Australia
appears to have been settled by an early wave with very archaic
features, followed by later groups which appear very modern. That
blend is still apparent in current populations.
|> >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.
Aside from height, the most obvious difference is hair type;
australian aborigines don't have kinky/frizzy hair.
|> 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.
Yes - this is the in-situ hypothesis: the negrito evolved as a
rainforest-adapted subspecies during the million-year hominid
occupancy of SE asia. It's possible. Equatorial rainforests are not
subject to the nearly the same level of ecological fluctuation as
temperate zones.
|> 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.
Small size is an advantage in the rainforest, but it's a huge
disadvantage anywhere else. I have a hard time imagining them
migrating over any distance through open country, particularly during
times of environmental stress. Both in asia and in africa, neighboring
peoples attempt to exploit negrito and pygmy on a very unequal basis.
|> 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?
Good question - I haven't seen any serious anatomical analysis.
|> 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.
Taking the obvious trait of the tightly curled hair, which is
adaptive in high-radiation areas but not in the shady rainforest,
provides some support for the common-ancestry htpothesis.
|> >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.
To some extent they are, but the presence of high mountains creates
rain shadows that will produce deserts. And deserts are the most
extreme case; any non-jungle environment seems like a barrier to pygmy
migration.
--
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