Joined: 07 Oct 2007 {Posts: 203 } Location: United States
Posted: Sat 30 Aug 2008 00:46 Post subject: Negritos, Asian pygmies, and Oceaneans
A couple questions, mainly for Frank and William:
1. Am I correct in assuming that these groups were indigenous to their region?
2. Weren't Oceanean decendants the folks who first left Africa? When it comes to "genetic distance maps," would this fact make them genetically the population that is the most different from Africans dispite similarities in skin color, and other features?
3. Were these features that are comparable to African features likely adaptations to the region, or are they more than likely features that were already present in the migrant populations (and did not change because of similar climates and diets?
Sorry. I am not sure that I understand what you mean by "Oceaneans." Polynesians (Tahiti, Hawaii, New Zealand, etc.) spread across the Pacific from what is today Indo-China starting about 2 KYA. Melanesians (Borneo, Australia, Papua-New Guinea, Fiji) also launched from southeast Asia but much earlier (about 45KYA). Finally, as far as anyone knows, the Negritos of the Andaman Islands have been in place since earlier yet, probably about 65 KYA.
All are now "indigenous" to their current locations but all descend from people who originally migrated from elsewhere: Polynesians most recently, Melanesians earlier, and Negritos even earlier yet. If you can tell me which specific group you are interested in, I shall try to recommend a source.
Regarding who "first left Africa," I believe that there was only one small group who left Africa by crossing the Straits of Bab-El-Mandeb about 74 KYA. With a couple of exceptions, everyone who is native to any region outside of Africa today ultimately descends from that same small group. Hence, every non-Africans' ancestors left Africa at the same time, since every non-African has those same ancestors.
The exceptions are: (1) a few additional Africans migrated to Europe when the glaciers melted about 15 KYA and (2) since about 5 KYA (Ur, Sumer, Minos, Egypt, Greece, Rome) African slaves have been taken everywhere.
Joined: 07 Oct 2007 {Posts: 203 } Location: United States
Posted: Wed 03 Sep 2008 02:53 Post subject:
fwsweet wrote:
Sorry. I am not sure that I understand what you mean by "Oceaneans." Polynesians (Tahiti, Hawaii, New Zealand, etc.) spread across the Pacific from what is today Indo-China starting about 2 KYA. Melanesians (Borneo, Australia, Papua-New Guinea, Fiji) also launched from southeast Asia but much earlier (about 45KYA). Finally, as far as anyone knows, the Negritos of the Andaman Islands have been in place since earlier yet, probably about 65 KYA.
Basically, by Oceanians (correct spelling, i think) I meant specifically those darker skinned groups of the region whom look comparable to many Subsaharan African populations (ie dark skin, curly or kinky hair, broad ish nose). Specifically Negritos...
It was stupid of me not to realise and acknowledge the fact that there were many migrations that formed those current populations, so it should have been assumed that "Oceanians" weren't a homogeneous population. That was my fault.
Quote:
All are now "indigenous" to their current locations but all descend from people who originally migrated from elsewhere: Polynesians most recently, Melanesians earlier, and Negritos even earlier yet. If you can tell me which specific group you are interested in, I shall try to recommend a source.
Interesting....
Quote:
Regarding who "first left Africa," I believe that there was only one small group who left Africa by crossing the Straits of Bab-El-Mandeb about 74 KYA. With a couple of exceptions, everyone who is native to any region outside of Africa today ultimately descends from that same small group. Hence, every non-Africans' ancestors left Africa at the same time, since every non-African has those same ancestors.
Basically, I saw the map and noticed that the only populations that existed outside of Africa were those in the Arabian penn., the whole southern coast of Asia, and Oceania (haplogroup M). I wrongfully assumed that this made the modern decendants of those populations that much removed from Africa when it comes to "genetic distance." As you've said, they all left at the same time, so i guess time doesn't say much about genetic distance between non - african populations and African populations. i honestly don't know.
I guess I need to learn more about whatever this "genetic distance" really is, and how it's determined.
One question remains: 3. Were these features (dark skin, kinky hair, broad nose) that are comparable to African features likely adaptations to the region, or are they more than likely features that were already present in the migrant populations (and did not change because of similar climates and diets? I'm guessing the latter.
Basically, by Oceanians (correct spelling, i think) I meant specifically those darker skinned groups of the region whom look comparable to many Subsaharan African populations (ie dark skin, curly or kinky hair, broad ish nose). Specifically Negritos...
Oh. Okay. Unfortunately, I am not very familiar with the Andaman Islanders. Salsassin knows more about them than I do, but he has been suspended until next year for constantly getting into fights. I would suggest googling (prehistoric "Andaman Islands").
From the little that I know, they are among the oldest out-of-Africa populations. Their ancestors migrated there from Africa in the original diaspora of 75 kya, and have apparently been there ever since. I say "apparently" because this assumes that the Toba eruption predates the diaspora. If you assume that the diaspora predates the Toba eruption, then it is hard to see how they could possibly have survived, and so must descend from more recent immigrants.
They do superficially resemble some modern sub-saharans (hence their label "Negritos"), but I do not think that anyone has found solid evidence either way. On the one hand, as you say, it seems too much of a coincidence that they would have evolved the same features independently.
On the other hand, many people think that native Australians and New Guineans also "look sub-saharan." Also, the Africans whose DNA is ancestral to that of everyone outside of Africa are Ethiopians and Khoi-San, who are much lighter than either the Andaman islanders or the modern Bantu-speaking sub-Saharans.
I suspect that it is a little of both. Some traits (tightly curled hair) are probably ancestral, while other traits (like dark skin) are an adaptation that is common everywhere that receives a lot of solar UV.
I think that "genetic distance" results more from isolation consequent to splitting and migration than elapsed time. It is an obsolescent and crude measure though. Most phylogeographers nowadays use genetic tree graphs for tracking population movements, not "genetic distance."
Regarding the National Geographic maps, I think that they are hard to understand because they show too much information. For one thing they include irrelevant material about H. erectus and H. neanderthalensis rather than sticking to H. sapiens. Also, they include a note about hybridization between sapiens and erectus, for which there is no shred of evidence, and which seems exceedingly improbable given the millions of years of separation between the two species.
Another thing to keep in mind is that the entire field of prehistoric human phylogeography is so new that discoveries are made all the time. As I said, I recommend Journey of Mankind - The Peopling of the World, but even it has problems. I already mentioned one. No one has good evidence whether the Diaspora happened before or after Toba. Another problem is the unknown impact of the back-flow from Asia to Africa that happened 40-45 kya. (My own Y, for example, is found only in northern Cameroon today, but it originated 50 kya in Asia Minor.)
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