Homo naledi is the latest addition to our fossil family. Since this enigmatic relative of ours was discovered a few years ago news has been trickling out. Each discovery seems to add more questions than answers. Notably, it was recently found to have lived only ~300,000 years ago. Yet it looks a lot older than that. Weird. Now, a whole batch of new fossils have been recovered from the Lesedi Chamber and true to form, they don't clear much up.
Lesedi Chamber Introduction
Up until now all Homo naledi fossils had come from one chamber in that one cave. Now some have been discovered elsewhere . . . in another chamber of the same cave. I guess Homo naledi was just a really big fan of this one cave.
The Lesedi Chamber itself is more than 100 metres away from the Dinaledi Chamber through a series of twists and turns. This confirms that the two represent separate deposits, and fossils from one haven't somehow tumbled into the other (I think that would be a super determined fossil to do so). Another interesting point about this chamber is that it's a lot easier to get into. The Dinaledi Chamber was behind a famously narrow crawl, to the point that only small members of the team could reach it. But it looks like even schlubs like me could reach the Lesedi Chamber.
The chamber itself contains at three individuals, represented by dozens of fossils. I don't envy whoever had to put that jigsaw back together. But they did, and it looks like the three individuals consist of two adults and a juvenile. One adult is notable for being particularly large, with a brain volume of more than 600 cc. Now that might not sound like much compared to our 1300 cc, but it's nearly 1/3 bigger than the other Homo naledi found so far.
More mysteries
Almost every discovery about Homo naledi has raised more questions than it answered. Like how a simple examination of the teeth revealed it had a unique diet. Perhaps the only time this didn't happen is when researchers were simply able to confirm there was another fossil individual amongst all the bones they'd found. Well, the Lesesdi chamber is no exception.
The big on-going mystery about the cave is whether it represents a burial site. People have been going back and forth on this for quite a while. Part of the evidence for this came from the fact that the Dinaledi chamber was so hard to reach. Corpses clearly couldn't have got there without some sort of intervention. So where does the relatively easy to access Lesedi Chamber fit into it? Might that throw things up in the air?
Another big question is what sorts of tools might the species have used. We've found none in the cave so far (part of the reason people think it was a burial site. It clearly wasn't lived in). Now there's a second chamber and still no tools. Might we have to face up to the fact this was a hominin that didn't use stone tools? It would be the first one to be in that situation for nearly 2 million years.
Finally, we're trying to figure out where the species falls within the human family tree. One idea is that it might be a remnant of an earlier lineage, hence why it is so old-looking yet lived so recently. This raises the question: were the two sets of fossils deposited at the same time? Given the broad similarities between them, the researchers think they were. But there's no dates for the Lesedi Chamber to confirm this.
tl;dr
Homo naledi is an enigmatic species. Finding another three individuals in another part of the cave hasn't done much to clear it up. But it does show there's a lot more fossil material out there, so hopefully some questions will be answered in the long run.
References
Hawks, J., Elliott, M., Schmid, P., Churchill, S.E., de Ruiter, D.J., Roberts, E.M., Hilbert-Wolf, H., Garvin, H.M., Williams, S.A., Delezene, L.K. and Feuerriegel, E.M., 2017. New fossil remains of Homo naledi from the Lesedi Chamber, South Africa. eLife, 6, p.e24232.
