Omnivorous writes:
Here's a summary of the debate by David Johanson:
Please note I am quoting Johanson through Omnivorius' post.
The Multiregional Hypothesis:
some level of gene flow between geographically separated populations prevented speciation after the dispersal
Seems reasonable, particularly considering recent findings.
all living humans derive from the species Homo erectus that left Africa nearly two million-years-ago
Seems unreasonable, particularly considering recent findings.
natural selection in regional populations, ever since their original dispersal, is responsible for the regional variants (sometimes called races) we see today
As Damon Wayans when playing the clown from In Living Color would say "homie don't think so" right before he clubbed someone over the head. Recent DNA evidence indicates all are essentially modern Homo Sapiens, with a slight bit of spice from Neanderthals and/or Denisovans.
the emergence of Homo sapiens was not restricted to any one area, but was a phenomenon that occurred throughout the entire geographic range where humans lived
Doubtful, smells like appeal to magic.
Now for the converse:
In contrast, the Out of Africa Model asserts that modern humans evolved relatively recently in Africa, migrated into Eurasia and replaced all populations which had descended from Homo erectus.
Critical to this model are the following tenets:
homo sapiens arose in Africa and migrated to other parts of the world to replace other hominid species, including homo erectus;
Homo Erectus appears to be more a cousin than a direct ancestor according to the most modern interpretations of physical anthropology, in accordance with actual physical measurements of the fossils.
after Homo erectus migrated out of Africa the different populations became reproductively isolated, evolving independently, and in some cases like the Neanderthals, into separate species
Guess we will have to wait for some shred of DNA from Homo Erectus to make this one work out. In the meantime it appears both Homo Sapiens and Neanderthals evolved from Homo Rhodesiensis, rather than Homo Erectus.
Homo sapiens arose in one place, probably Africa (geographically this includes the Middle East)
This hypothesis would, of course, fit in with the evolution of any other critter, be it observed or evidenced by the scanty fossil record.
Homo sapiens ultimately migrated out of Africa and replaced all other human populations, without interbreeding
Oops, the most recent DNA evidence indicates their was some slight inbreeding between modern Homo Sapiens, Neanderthals and the more recently speculated Denisovans.
modern human variation is a relatively recent phenomenon
Almost entirely, except for that lil' bit of DNA evidence.
I think the 'Out of Africa' hypothesis is mostly correct except for that smidgen of DNA from our distant cousins, none of which has been shown to be from erectus. One reason I see slight interbreeding is due to that old saying from New Mexico Tech "Socorro, where women are men and sheep are restless."
Reality is always more complex than a slogan.
The idea of the sacred is quite simply one of the most conservative notions in any culture, because it seeks to turn other ideas - uncertainty, progress, change - into crimes.
Salman Rushdie
This rudderless world is not shaped by vague metaphysical forces. It is not God who kills the children. Not fate that butchers them or destiny that feeds them to the dogs. It’s us. Only us. - the character Rorschach in Watchmen
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