When Darwin first proposed that humans evolved from apes many though the orangutan was closest to our ancestor. After all, they walk in a suprisingly similar way. As such a lot of early fossil hunters looked for our ancestors in Asia; hence why so many early discoveries have names like "Peking man" or "Java man". It wasn't until the 1920s that Africa became the focus of research.
But could this be reversed (again)? Did Asia play a more prominent role in our evolution than we thought? That's potential implication of fascinating new data from China, which may rewrite our understanding of human evolution.
The data
This new information comes from Longgupo Cave, in China. There teeth from several species have been recovered ( including Gigantopithecus, the giant ape); the most notable of which are 10 or so which have been identified as hominin (belonging to the human family). Stone tools have also been recovered from the site, further suggesting it was occupied by members of the human family.
So far nothing unusual. Our ancestors may have evolved in Africa, but ~1.9 million years ago Homo erectus (the first hominin with a body you might call "modern") left our homeland and spread around the world. They've been found as far north as Britain and as far east as Indonesia.
However, things started to get interesting when a team of researchers tried to redate the site. By examining the decay of isotopes in the enamel of the animal teeth, they concluded that the hominins were inhabiting the site 2.4 million years ago!
That's half a million years before Homo erectus even evolved; let alone made the "first" migration out of Africa. ( Maybe) even before any sort of human had evolved! This clearly has some pretty profound implications for human evolution.
Some pretty profound implications for human evolution
So, there were hominins in China before Homo erectus. Maybe even before Homo. Is this really that big a deal? Yes! It's hard to say just how big a deal for sure - since all we have to go on are some teeth - but even the simplest (and thus most likely) implications of this find could really shake up how we view human evolution. To explore this further I've listed out some of the possible implications of this study, ranked in order of likliness.
- The most likely explanation is that there was a pre-erectus migration out of Africa. This would be very significant as many people think the modern-ness of Homo erectus played a key role in making that migration possible. If not, we'd have to re-evaluate what makes us so special and why those features evolved. It would also help explain why there are some "primitive" fossils in Asia.
- There was a pre-erectus migration out of Africa that then began evolving independently. This doesn't seem too far fetched (the Neanderthals, for example, are a case of this happening) and it would explain a lot of quirks about the "erectus" migration. Asian erectus has some unique anatomical and cultural traits that cause some to label it a different species. Could this be because they're a separate branch.
- There was a pre-erectus migration out of Africa that then began evolving independently and some of that evolution fed back into us. When modern humans migrated, we interbred with some of the earlier migrations. Could this have happened with Homo erectus? Did this Chinese developments feed back into the "main" human linage?
As I said, even if you view this discovery with caution this has some huge implications for our evolution.
Seems like a big change to make based on some teeth
Ah yes. My mental construct of my readers is clever. You're right to be skeptical, there are some issues with this research. Most obviously are a few methodological failings. They only use one dating method; and that method is relatively uncommon. As such we don't have as much data on how reliable it might be.
But there's also a bigger problem. What if they aren't hominin teeth at all? They're hardly the most unique aspect of our anatomy, can we really identify them as human? That's a point the initial discover of these teeth has conceded; acknowledging that they're probably just ape teeth after all.
And with that; all these tantalising implications dry up. Human evolution goes back to normal. Another hominin fossil from Longuppo could throw it all in the air again; but until then there's sadly nothing to see here.
Reference
Han, F., Bahain, J. J., Deng, C., Boëda, É., Hou, Y., Wei, G., ... & Yin, G. (2015). The earliest evidence of hominid settlement in China: Combined electron spin resonance and uranium series (ESR/U-series) dating of mammalian fossil teeth from Longgupo cave. Quaternary International.