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


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.

Burials from Qafzeh cave in Israel. They were some of the first humans to migrate out of Africa

Burials from Qafzeh cave in Israel. They were some of the first humans to migrate out of 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 it’s 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.

Some of the Chinese teeth (Daoxian) compared to teeth from other time periods and species

Some of the Chinese teeth (Daoxian) compared to teeth from other time periods and species. However, note how there is extensive overlap between the anatomy of these species

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.

References

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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3 thoughts on “Early “failed” migration out of Africa was actually successful”

  1. zac in San Francisco says:

    One fundamental question I have, is whether the various waves of migration could be just the top of the iceberg in terms of total mobility.

    100k years, 50k years, 10k years even 2k years is a long time! I think that current thinking is that settlement of the America’s by a relatively small number of individuals coming across “Beringia” 12-14K years ago managed to spread out across North and South America all the way to Patagonia in only a few thousand years (someone with a bit more knowledge help me out here!)

    If people (as few as 70 individuals) can spread so wide and far this quickly, couldn’t there have been any number of waves- “ebb tides” really of humans coming and going in and out of Africa, Europe, the Mid-east, Asia…? Even if the populations were small, we rely on an extremely small set of pieces of evidence (homo remains, tools and tool making byproducts, animal bones with tool scrapings, hearths, art and other items clearly homo-made etc.) compared to populations over thousands of years.

    Couldn’t we be missing plenty of evidence of other migrations. Seems plausible that for many reasons (climate, better hunting, disease, inter-group conflict etc.) a group of people could have wondered in a general direction eventually succeeding in establishing a new home where they could have thrived for a few generations to a thousand years only to eventually disappear as well

    Does anything in the current DNA analysis eliminate the possibility of my dope-headed un-trained question?

    1. Adam Benton says:

      That’s definitely the case. The migrations we discuss are the broad patterns of movement of humans; but within these broad strokes many more fine-grained migrations were likely happening.

      However, when discussing these shorter scale migrations is worth noting that they probably weren’t particularly large or long distance. Most “migrations” basically consist of a few families moving over to the next valley. Humans rarely set off with the intent to colonise a distant land.

      So yes, there were other population movements; but these were likely very low numbers and short distance.

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