# Out of Africa / Human Origins - Revisited



## Steerpike (Sep 17, 2012)

An interesting summary of a good deal of information on the origins of modern humans. This sort of thing might be useful to the world building of some, if you get that in-depth in terms of how your races evolved and moved around the planet.

Rethinking "out Of Africa" | Conversation | Edge


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## CupofJoe (Sep 18, 2012)

An interesting read... every few years it seems to get more and more complicated - and more fun!


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## Ravana (Sep 18, 2012)

One of the things I remember most distinctly from my one course in Physical Anthropology was how much skulls from Africa assigned to _Homo erectus_ differed from those found in Asia–and how much more closely the latter resembled modern humans in terms of features such as reduced supraorbital ridges and sagittal crests. Which always made me wonder why these _were_ regarded as the same species, given how often those features were invoked to define differences between African finds. And I always suspected, perhaps uncharitably, that the assignments were made solely on ascribed (possibly incorrectly ascribed) dates, in order to prevent the Asian finds from being viewed as a possible intermediate step between the older African species and modern humans.

I've also never been able to accept out-of-Africa "waves" as a terribly plausible model: it doesn't strike me as parsimonious to suggest that one group of pre-modern humans emerged from Africa, swept across much of the planet, then was replaced by another, and another. That may work when talking about mass migrations emerging from the Asian steppes in the historical period; it does not work so well for vastly smaller bands little larger than extended family groups… if larger at all. I consider it far more probable that a constant flow of genes took place once humans began spreading out and filling up every niche they could locate. How many generations would it take for a gene to progress from one end of Eurasia to the other? A thousand? Trivial, on the time spans being considered. All of civilized history has barely taken half that. A slow, constant genetic exchange model would account for such "problems" as Neanderthal and Denisovan gene presences far better, I would think. 

(Interestingly, a third model–parallel evolution following early migrations–would more readily account for the morphological differences between Asian and African _erectus_, as well as possibly offer interesting insights into such things as language families. At least it would were it not for the unavoidable and unparsimonious, not to mention highly inflammatory, consequence of implying that there are two different "human races" which just happened to remain interfertile. I find it difficult to imagine the answers lie in _that_ direction, nor am I aware of anyone who does support it. Not outside of China, at least.)


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## Jabrosky (Sep 18, 2012)

Ravana said:


> One of the things I remember most distinctly from my one course in Physical Anthropology was how much skulls from Africa assigned to _Homo erectus_ differed from those found in Asia—and how much more closely the latter resembled modern humans in terms of features such as reduced supraorbital ridges and sagittal crests. Which always made me wonder why these _were_ regarded as the same species, given how often those features were invoked to define differences between African finds. And I always suspected, perhaps uncharitably, that the assignments were made solely on ascribed (possibly incorrectly ascribed) dates, in order to prevent the Asian finds from being viewed as a possible intermediate step between the older African species and modern humans.


When did you take this class? According to the notes I took for _my _Human Evolution class last year, the African _Homo erectus_ (or _Homo ergaster_) is the variant with the more modern human-like morphology whereas the Asian _erectus _has the more robust brow ridges and sagittal keel.


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