So 13 months after the start of this thread, the Out of Africa model has gotten a lot more complex. The original argument was that all human populations outside of Africa are descended from a group of anatomically modern humans who left Africa about 60,000 years ago. This image from an article published in the journal nature just a few days ago summarizes most of the issues:



1) Kuhlwilm et al 2016 found anatomically modern human DNA in a ~100,000 year old Neanderthal in the Altai Mountains. This AMH DNA appears to be from a group who diverged from most (all?) modern humans before modern Eurasians diverged from sub-Saharan Africans. There was a group of hominids already known to have inhabited the Galilee in modern Israel c. 120,000-80,000 years ago who had a mix of modern and archaic features. They replaced Neanderthals in the area and then were replaced by Neanderthals, so it had been assumed that they were a failed early out of Africa population who didn't get any further, but then modern human teeth were found in China that date to roughly 100,000 years ago. It's notable that this AMH admixture has only been found in an Eastern Neanderthal.

2) Neanderthal admixture in modern Eurasians (already discussed) appears to date to 50,000-60,000 years ago and comes from Western Neanderthals not Eastern Neanderthals. Despite this, East Eurasians have more Neanderthal admixture than Europeans.

3) Denisovans, another line of hominin found in the Altai Mountains, contributed ancestry to Eastern Eurasians maxing in Papuans.

4) Eastern Neanderthal DNA has been found in Denisovans.

5) On top of all that, Denisovans received DNA from a mystery hominin who diverged from the rest even earlier.

Here is another visualization with conservative admixture percentages:



Though this was published just six days ago, it's already out of date because introgression of some other previously unknown archaic hominin was found in Pygmies.

Taken altogether, this actually strengthens the minority argument that anatomically modern humans might have arisen first in the Middle East, although I think the evidence for African origin is still much stronger and the oldest remains have been found in Ethiopia. Although it's basically a debate about which side of the Red Sea, rather than a debate about which continent broadly speaking, and if we're talking about a breeding population with a range, it doesn't necessarily have to be one side or the other.