Biology Magazine

Early “failed” Migration out of Africa Was Actually Successful

Posted on the 27 October 2015 by Reprieve @EvoAnth
Early “failed” migration out of Africa was actually successful

Humans evolved in Africa within the last 200,000 years. However, they didn't hang around for long. By ~120,000 years ago modern humans began migrating out of Africa and into the Middle East. Yet they didn't stick around there either; disappearing shortly after they first arrived. It was long thought that they had retreated back into Africa and this first migration was a failure. However, new evidence reveals that these early pioneers may have managed to continue migrating after all; making it as far as China.

Fossils from Israel show that modern humans made it out of Africa ~120,000 years ago. There they hung out and did all sorts of exciting human-type stuff; like carrying out the first intentional burials. However, changing climates made the region inhospitable and they vanished ~80 thousand years ago (replaced by Neanderthals, whose hardy anatomy was well suited to these harsher climates). It was thought that this initial out of Africa migration was a failure, with these Israeli individuals either going extinct or retreating back into Africa.

However, dozens of teeth from sites across Southern China challenge this narrative. Anatomical comparisons reveal that they're very similar to modern humans. Genetic evidence from modern populations indicates that humans arrived in the region 50 - 60 thousand years ago. Which is what makes these teeth so special. They appear to be closer to ~80,000 years old (possibly even older than 100,000 years).

These earlier dates match up quite nicely with the migration into the Middle East (and the subsequent abandonment of it). Might these teeth represent another branch of this first migration. Perhaps its where the people from Israel went when the climate began to change. Without the rest of the body (or genetics) to compare the two populations we can't say for sure; but the timing does make it likely they were part of the same "wave" of migration.

At least; that's what happened if these teeth can be trusted. As the diagram above shows, there is often significant overlap between the different human species. These teeth are still pretty clearly human; it's just that teeth alone may not be the best way to identify species. The rest of the body would be nice to have. The earliest complete human skeletons from Asia we have date to ~50,000 years ago; fitting in nicely with the genetic evidence.

Still, this doesn't mean we can throw away these interesting new discoveries (just take them with some salt; or another Chinese condiment of your choice). It's still is pretty nice evidence that the initial spread of modern humans wasn't a complete failure.

We weren't chased back into Africa by Neanderthals and changing climates. However, it can hardly be counted as a success either. As I previously mentioned, the genetic data indicates that modern populations began arriving in Asia much later; ~50,000 years ago. Thus, it would seem that this initial wave ultimately died off. They traveled further and lasted longer than we thought, but still went extinct in the end. It was later migrations out of Africa that gave rise to the modern populations that live around the world today.


Boyd and Silk, 2015. How Humans Evolved

Curnoe, D., Ji, X., Shaojin, H., Taçon, P. S., & Li, Y. (2015). Dental remains from Longtanshan cave 1 (Yunnan, China), and the initial presence of anatomically modern humans in East Asia. Quaternary International.

Demeter F, Shackelford LL, Bacon AM, Duringer P, Westaway K, Sayavongkhamdy T, Braga J, Sichanthongtip P, Khamdalavong P, Ponche JL, Wang H, Lundstrom C, Patole-Edoumba E, & Karpoff AM (2012). Anatomically modern human in Southeast Asia (Laos) by 46 ka. Proceedings of the National Academy of Sciences of the United States of America

Liu, W., Martinón-Torres, M., Cai, Y. J., Xing, S., Tong, H. W., Pei, S. W., ... & Wu, X. J. (2015). The earliest unequivocally modern humans in southern China. Nature.

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