Humans are the only living species to perform elaborate burials. Even during last ice age, we were investing a huge amount of effort in funerals. But just how old is this behaviour?
It turns out it might be older than we think. There is possible evidence burials could be close to half a million years old, stretching back into earlier human species. Most recently, palaeoanthropologists found the archaic-looking Homo naledi deep in a cave. Their fossils were so inaccessible they thought natural processes couldn't explain their location. Instead, they speculated their kin must have deliberately buried them there.
But not everyone finds these claims of early burials convincing. And now, artificial neural networks are lending this skepticism some support. They indicate that we can't rule out natural causes for many of these alleged "burials" 1.
The burials
Burials of modern humans are a dime a dozen. Even recent hominin species, like the Neanderthals, have their fair share of burials. However, move a hundred thousand years further back and the evidence becomes much rarer.
Ultimately, only two possible burial sites from that period have stood up to repeated scrutiny. They are the aforementioned Homo naledi fossils and the Sima de los Huesos site in Spain. Both clock in at close to half a million years ago, making them possibly the oldest known burials. Assuming that's what they actually are, of course 1.
And the similarities don't end there. In both cases, a whole bunch of hominin bones were found where they shouldn't be. In the case of Homo naledi, it was deep in a difficult to navigate cave. For the Spanish site, thousands of bones were found at the bottom of a natural "chimney". Plus, neither site contains stone tools, chewed food, or any of the usual evidence that the place was lived in 1.
Thus, it has been argued that the only way so many bones could get to such a difficult to reach location was if it was done deliberately. Of course, that's something of an argument from ignorance. "I can't think of how these bones got in the cave so it must have been a burial". As such, many remain skeptical of these sites until more compelling evidence is found 1.
But perhaps those skeptics are being too harsh. After all, if every other explanation has been ruled out then burial must be right. So, some researchers asked an AI if that is indeed the case.
The AI
Ok, calling it an AI may be overselling it a bit. They didn't go up to Deep Thought and ask what was going on. Rather, they used machine learning to train a computer to identify burials caused by humans and how they differed from those caused by predators.
This process involved giving the computer more than 15 examples of "burial" to analyse. These ranged from known cases of deliberate burial by ancient humans to primates that died of natural causes and were just left in the woods. After all this training, they unleashed it upon Sima de los Huesos and Homo naledi to see what it said.
The results were...ambiguous.
Essentially, the computer concluded that these sites share similarities with both sites that have natural causes and deliberate burials by humans. As such, it couldn't rule either out.
This might sound like we're back to square one, but the circumstances which cause this ambiguousness is quite interesting. The analysis indicates both sites were heavily disturbed after their initial formation. Perhaps future research can figure out what it is and we can take it into account in our analysis 1.
Of course, this sort of silver lining depends on the fact that this deep learning gave us accurate results. However, these sorts of studies are only as good as the data being fed into the computer in the first place. This creates a bit of a vicious circle since we don't have a confirmed case of ancient burial to teach the computer.
So for now, it seems that AI won't be answering our big archaeological questions. Which is good for my job security, but less good for people who came here wanting answers. Sorry about that.
References
- Egeland, C.P., Domínguez-Rodrigo, M., Pickering, T.R., Menter, C.G. and Heaton, J.L., 2018. Hominin skeletal part abundances and claims of deliberate disposal of corpses in the Middle Pleistocene. Proceedings of the National Academy of Sciences, p.201718678. https://doi.org/10.1073/pnas.1718678115
