Re: puzzle of the negrito: isolated archaic populations
Philip Deitiker (pdeitik@bcm.tmc.edu)
Fri, 13 Dec 1996 18:32:41 GMT
geroldf@sdd.hp.com (Gerold Firl) wrote:
>In article <589qd4$3er@gazette.bcm.tmc.edu>, pdeitik@bcm.tmc.edu (Philip Deitiker) writes:
>|> geroldf@sdd.hp.com (Gerold Firl) wrote:
>|> >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?
>|> Gerald, wake up! This one has actually been addressed. The population
>|> found in the Solomon islands and adjacent areas turn out to be about
>|> 45,000 year old isolates of the first groups to enter asia.
>Aren't the solomon islanders melanesian? Both melanesians and negrito
>have kinky hair, but it seems a bit premature to link them purely on
>that basis.
melanesia can be divided along two lines, the solomon island-like
folks and classical east asains. The solomon island/autralo aboriginal
peoples represent an anceint (diverged) subgroups of widely scattered
people with several characterisitics in common (when comparing them
with other eurasians).
1. They migrated to the region somewhere about 55 - 40 KYA
2. In this migration they split early and gene flow between isolate
populations has been small. Again not all populations have been tested
and these are presumptions for all populations, but I strongly suspect
that the other negrito populations are going to have similar
divergence characteristic. This spread of ancient asiatics presents
several problems and I will mention these.
First, there is some evidence that there has been hybridization
between recently arrived asians and these ancient dwellers, this has
produced, by eurasian standards, genetically new populations. Each
mixing event, given the standing differences in ancient isolates is
going to have a completely different result. As a result if the
presented studies stand up, one is probably going to see 20 or 30
genetically seperable populations in the southeast asia/autralia/south
pacific region alone. This is why when you say 20 or 30 groups for the
world I kind of hold back, I suspect that africa and southeast asia
are regions where the current list can be expanded greatly and where
past definitions of what constitutes a group will be challenged. An
example might be papau new guinea where >3 qualifyable groups live on
a single island. This can be contrasted with precolumbian south and
central america which would be composed of 1.
Anyway you have to read the paper, the solomon islanders were
highlighted becasue there was a trait of blond hair in the population,
which is only seen in remote regions of africa and lead people to
believe that this group may have migrated recently from african. The
genetic strudies reveal that their closest relation is with southeast
asians (slight relative) and again the divergence time is about 45 KY.
>Also, h. erectus first entered asia about a million years ago. There
>has been a whole lot of evolution going on since. This area of the
>world is one of the places which makes the out-of-africa/genocide
>hypothesis look very questionable.
Maybe, I think it's very doubtful, though, if your making the argument
that way over here there is a group which hasn't been throughly tested
and possibly of non-african origin. There has been no other instance
that supports this belief and there is no set of charactersitcs which
suggest these people have superafrican traits (i.e. traits above and
beyond those represented by the total of other of tested humanity)
>There is a
>|> synapsis on this in Science, about a year ago. The gene studies
>|> haven't been done for all, but I beleive three of the populations have
>|> been identified. Ironically, I think the data shows that these peoples
>|> are the most diverged from from current african populations, basically
>|> showing that when it comes to genetic makeup, inheritiance can be
>|> deceiving.
>I'm not sure which populations you refer to - melanesian? negrito?
>papuan? australian? vedda? And which african populations - negro or
>pygmy?
comparing solomon-like folks with classical east asians
>It wouldn't be surprising if the blue-water island populations prove
>to be modern, recent isolates.
Some are young (1 to 5 KYA) others present as being isolated for
(based on what I read) ~42 KY isolates. These groups are scattered
throughout the east indian and south pacific oceans, and interestingly
maintain a high degree of social separation. These peoples body forms
have consistent form and I suspect represent long term local evolution
with many similar selective pressures based upon common human
variations.
>The polynesian settlements are *very*
>recent, and open-ocean technology is viewed with scepticism anywhere
>beyond 40,000 b.p. or so. Java, on the other hand, had residant
>hominids a million years ago
True, but the fossile record dries up after that and I'm not even sure
that there were non-HS hominids in this subequatorial region when the
75K - 50KY migrants came across. There is the belief that somewhere
along the way there was a 60 mile stretch of water that had to be
crossed, and the best evidence suggests that it was first crossed 50
to 45 KYA. The latest dating for Peking man puts him at 400 KY old and
there is little evidence from that period to the present suggesting HE
presence (And I agree it seems odd that there shouldn't be). So unlike
what has been discovered in europe, which can be summerized as
evidence for interspecies cultural exchange (with a lack of any
genetic exchange) in southeast asia there is simply no evidence for
temporal territorial overlap. In addition there is no reason, based on
genetic studies, to suggest that these ancient southeast asians are
not out of africa.
If I was looking for a spur older than any spur detected in africa
(inclusive of the rest of typed eurasia) I would be looking at certain
characteristics which might be consistent with a > 200KY separation.
Such characteristics would be obvious. Examples might be extreme
differences of brain size to body, alteration in the skeleta,
particularly the hands and feet, the throat, facial brow etc. One
might also look for differences in gestation period, age of
maturation. From a chromosomal point of view a >200 KYO spur is going
to present noticably different karotype. Some or many of these things
should be obvious by now. What we see in this peoples are a different
mix of traits already seen in the presumptaviely african derived
population. Faster evolving loci such as HLA are going to present new
genotypes, but one has to focus on genes which are likely to change
over 10E5 to 10E6 years, not 10E3 to 10E4.
BTW, Unlike the IE, mediterraneans, chinese, and native americans (the
eurasioan dervied folks) this group (as we disscussed earlier) this is
an example of groups which do maintain a notable set of
characteristics which point to long term separation. The types of long
term separations appear to be similar to africa in the sense that
deglaciation is not going to result in the degree of compression and
movement when compared to temperate climates. I strongly suspect that
the isolation is the result much static societies. Thus when one uses
eurasia as a standard for measuring differences there is an inherant
problem. Since eurasia was subject to glacial movements peoples get
pushed together and spread out and this likely results in a more
protracted gradient structure with the extreems of the gradient
truncated by mixing. If this had not occurred I think that over the
same periods of time one would see more dramatic differences in the
eurasian population consistant with those differences seen in the
ancient southeast asians. My point is that maybe we should treat
african and this population as the standard for judging human
evolution rather than a population (eurasian) that has a number of
stokastic phenomena associated with it.
Philip
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