"Race? It is a feeling, not a reality. Ninety-five per cent, at least. Nothing will ever make me believe that biologically pure races can be shown to exist today.... National pride has no need of the delirium of race." — Benito Mussolini

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[–]Tarsius 3 insightful - 1 fun3 insightful - 0 fun4 insightful - 1 fun -  (1 child)

The out of africa model is extremely likely as far as I know. Several hints, that Homo sapiens emerged in Africa: Most genetic diversity is in Africa, Human genetic trees almost always show some African tribes (I think the san) as the outgroup to all other human beings, neanderthal DNA is found in all non-African populations but not in all African populations.

Some concept of race making biological sense could be possible, but if you want to have phylogenetically sound races, you would likely have to have several African races and not so many outside Africa (eg Europeans and people from the Near East are genetically quite similar and have historically had a lot of intermixing.

[–]InvoluntaryHalibut 1 insightful - 1 fun1 insightful - 0 fun2 insightful - 1 fun -  (0 children)

The Khoi-San/Hadza/Sandawe group branched off first, around 150 thousand yeaars ago. They carry L0 mitochondrial DNA and haplogroup A y-chromosome which are deemed to be the “oldest” haplogroups.

Pygmies branched off from other humans next aroung 140 thousand years ago. (Y-chromosome B, mtDNA L1, L2 and a few other wacky L groups.

These hunter gatherer groups dominated most of the territory of sub-saharan africa up until as late as 3000 years ago. A large number of pygmy fossils discovered recently in west africa have helped to establish that.

Most people that we think of as african branched off much later from non-africans. Around 70 thousand years ago or so. West African/bantus and East Africans have mostly Y-chromosome E and a mixture of mtDNA L3 and a few other Pygmy and San types. There is a pretty interesting theory that haplogroups E and L3 actually arose in Asia and that a very large part of the ancestry of these two african groups was living outside africa for thousands of years. Group E is very close to D which is an East Asian haplogroup and L3 is very close to mtDNA macrogroups N an M, which is basically everybody else.

It is also clear that there has been serious influx of eurasian DNA into these two populations in the last 20,000 years or so, particularly East africans. The horn of africa looks alot like the middle east genetically esp. Arabia. There is also alot of R1b DNA in Chad which came from Eurasia in the same time frame.

So there are a lot of variations on OOA especially in terms of the timeline of exodus, details of back migration and extent of mixing with non-sapiens. Its all so messy.

Anyway, in my view, if you want to define race or a set of races and you assume you will be doing this on the basis of DNA and not culture than it is easy to sort humans in to a set of “buckets” or “pigeonholes” based on the quantity of single nucleotide pairs in common. This is just a mathematical excercise and the only variable is the number of buckets you want to sort people in to. The number of buckets (races) you chose to use to categorize humans is totally arbitrary, its a subjective decision. You could choose 5 or 50.

Here is an example that shows humans divide in to between 3 and 15 genetic buckets

http://dienekes.blogspot.com/2010/12/human-genetic-variation-first.html