Homo naledi is the most recent species to join the human family. And since its discovery a couple of years ago it seems to be doing its best to mess up our understanding of that family. Notably, it looks quite old, but it isn't. A new analysis of Homo naledi teeth has found even more mysteries. It seems that our new family member had a unique diet, unlike anything else in our group.
What's up with that?
Open wide
When it comes to examining the teeth of Homo naledi we have a lot of samples to choose from. Although we only know about the species from one cave, that one cave contains hundreds of fossils representing dozens of individuals. Thankfully, the resiliency of teeth means we also have a fairly sample of other hominin teeth to compare them too. This research compared hundreds of Homo naledi teeth with thousands of teeth from other species. The results were very surprising.
As I kind of gave away in the intro, it revealed that Homo naledi teeth were much more damaged than the other hominins examined. 44% of all Homo naledi teeth were chipped, which was more than double the rate seen in other hominins. And if that wasn't shocking enough for you, that's also nearly 8 times more chipped than the average chimp mouth. I should point out moder humans often have even more chipped teeth than Homo naledi, but compared to any other hominin species H. naledi was very unusual.
What's more, the sheer frequency of damage to their teeth isn't the only unusual thing about them. The damage was also surprisingly consistent across all teeth. Notably, most of it affected the gaps between the teeth. These are often small so hard to directly damage by sticking something in your mouth. Instead, such damage likely spends from a tough diet.
Of course, that doesn't narrow things down for us too much as there are many possible ways a diet can be "tough". Notably, it could feature tough food or be contaminated with tough objects, like grit. But given the consistently small size of the damage to Homo naledi teeth, the researchers think that a high-grit diet is the best explanation.
Homo naledi teeth to be trusted?
So, it seems that Homo naledi had a particularly gritty diet. What's more, it was more gritty than any other extinct hominin examined. Even those that lived nearby seem to have managed to avoid grit better than Homo naledi.
The reasons for this are many. The sample of human teeth with the most similar damage relied heavily on marine resources. The resulting shell, sand, and grit fragments caused a pattern of damage not dissimilar to Homo naledi. However, since the species lived so far from the coast this seems like an unsatisfactory explanation.
As you can probably see though, there's a lot of room for error here. Fortunately, there are many alternative ways to investigate the diet of extinct species. Unfortunatley, none of them have been done on Homo naledi just yet. So I can't really say exactly how sure we should be of these results. But with new fossils from the species still being found, it seems only a matter of time before we can confirm just how much grit Homo naledi liked to chew.
References
Towle, I., Irish, J.D. and De Groote, I., 2017. Behavioral inferences from the high levels of dental chipping in Homo naledi. American Journal of Physical Anthropology.
