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The recent discovery of the new member of the human family – Homo naledi – is very important for our understanding of human evolution. It helps confirm a lot of ideas we had about our ancestors (and as an added bonus, confuse creationists). However, there is one aspect of this find which contradicts existing ideas. This ancient, archaic hominin may have done a very modern thing: Did Homo naledi bury its dead?

The earliest clear evidence of our ancestors burying their dead is around 100,000 years old; from the Middle East. There is some (albeit contentious) evidence of burial occurring even earlier, in Spain ~400,000 years ago. Yet it is suggested that Homo naledi may have been burying their dead almost 2 million years ago! As if that isn’t shocking enough; there’s also the fact it had a brain the size of gorilla. Could an animal without our intelligence engage in such a human-like behaviour?

The evidence for this is pretty strong. The cave in which Homo naledi was found contains at least 15 individuals. These were found at varying depths in the sediment, suggesting that they accumulated over time. Such a long period and large accumulation suggests that something was going on here.

Now, burial isn’t the only “something” which could cause this sort of accumulation. A nearby cave in South Africa contains a lot of hominin fossils as well. This appears to be the result of the fact the cave used to have a hole in the roof. Unsuspecting Australopithecus wandering through the area fell in these imaginatively titled “death traps” and – you guessed it – died.

Malapa cave, where other human fossils accumulated

Malapa cave, where other human fossils accumulated

However, the thing about holes in the ground is that they don’t discriminate. As such, Malapa cave contains several other animals, as well as the human fossils. Yet Rising Star Cave – where Homo naledi was found – only contains fossils of Homo naledi (and a few other small animals that could get in their on their own steam).  Plus, there’s no sign that there ever was a hole in the roof of the cave.

Another likely alternative is that predators carried these animals into the cave to store and/or eat. We know that our early ancestors were easy prey, having found human fossils with bite marks. Yet these bitemarks are missing from the Homo naledi fossils. In fact, they don’t show much pre-death damage at all (or even signs of being eaten after death). All of the damage seems to have been done by bugs eating the decaying corpses. Or the changing levels of moisture in the cave breaking bones.

Homo naledi bones, showing grooves consistent with damage from bugs

Homo naledi bones, showing grooves consistent with damage from bugs

However, this doesn’t necessarily prove that no predators were involved. Perhaps the animal that stored the bones here forgot about them. Alternatively, since most of the fossils are partial skeletons the evidence of biting could simply be on the pieces we don’t have. That said, the researchers examining the cave claim this is an unlikely explanation since it’s so hard to reach the chamber the fossils were found in. Hell, it was really hard for the palaeoanthropologists to reach; requiring all sorts of gizmos and tiny people. As such, big cats probably wouldn’t have been routinely making that journey.

Other explanations they ruled out include the possibility water moved the bodies in there; since the deposits are relatively undisturbed. Or that these are just the result of individuals living in the chamber (since it’s so hard to get to).

So the only explanation left seemed to be that it was Homo naledi itself placing the bodies in the chamber. The bodies could be dropped down a slope into the chamber, avoiding the navigational difficulties that would’ve stopped predators reaching that inner room. If true, this behaviour would be very significant. This seems to be a case of a small-brained human relative engaging in the sort of symbolic behaviour we thought you needed a large brain for. In fact, burial of the dead is often thought to be one of those key developments that heralded the arrival of modern(ish) levels of intelligence.

A cross section of Rising Star Cave, showing the slope leading to the inner chamber bodies could have been dropped down

A cross section of Rising Star Cave, showing the slope leading to the inner chamber (fossil site 101) bodies could have been dropped down

However, before we get too far into a discussion of this finds significance it should be noted that there are a few issues with this conclusion. For starters, the Homo naledi fossils haven’t been dated yet. Sure, this would be very significant if it’s a case of 2 million year old humans burying their dead. But if it turns out it was happening last Tuesday (geologically speaking) then a lot of that significance vanishes. There’s also the fact that only a small part of fossils site 101 has been excavated thus far. The dismissal of many alternatives is based on a lack of evidence for them (e.g., no tooth marks from predators). Might the missing evidence be present in those unexcavated regions?

But perhaps the biggest issue is that the argument for burial is basically an argument from ignorance. They don’t provide much evidence for burial; simply rule out many alternatives. But until all alternatives are ruled out; burial isn’t proven. For instance, I have a suggestion: might Homo naledi have been seeking shelter in the cave. Just like modern chimps do on hot days. Some went a bit too far in, fell down the slope and couldn’t get back out.

Regardless, something very interesting is going on here. Maybe it’s human relatives behaving like chimps. Maybe it’s burial of the dead. More work is needed to figure out what exactly is going on though. So be excited, but don’t jump on the researchers’ bandwagon just yet.

References

Boyd and Silk, 2012. How Humans evolved.

Dirks, P. H., Kibii, J. M., Kuhn, B. F., Steininger, C., Churchill, S. E., Kramers, J. D., … & Berger, L. R. (2010). Geological setting and age of Australopithecus sediba from southern Africa. Science, 328(5975), 205-208.

Dirks, P. H., Berger, L. R., Roberts, E. M., Kramers, J. D., Hawks, J., Randolph-Quinney, P. S., … & Tucker, S. (2015). Geological and taphonomic context for the new hominin species Homo naledi from the Dinaledi Chamber, South Africa. eLife, 4, e09561.

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20 Comments

john zande · 6th October 2015 at 3:53 pm

To the best of your knowledge, when were the first burials with grave goods? From what i understand, the earliest known example today is 90,000 years ago. Is this correct?

    Adam Benton · 6th October 2015 at 4:49 pm

    Defining grave goods is a tad tricky. Particularly in early cases where only a handful of artefacts are “buried.” But yes, the general narrative puts the earliest grave goods at 90 – 100 kya; with the earliest burials at 110 – 115 kya.

    However, the super early Spanish site I mentioned does have a solitary handaxe. The fact this was the only tool recovered has lead some to suggest it was a deliberate placement and thus counts as grave goods.

Derek McComiskey · 6th October 2015 at 7:10 pm

“brain the size of a gorilla”: These were small creatures – so how does the relative brain/body size stack up with reference to other hominins.

    Adam Benton · 6th October 2015 at 11:44 pm

    It’s about similar to Australopithecus

Mike · 6th October 2015 at 8:22 pm

“Some went a bit too far in, fell down the slope and couldn’t get back out.”

How many can we believe for that kind of explanation? I don’t imagine it is likely that someone in with a newborn would explore deep in a cave nor is an old individual. Even with a chimp’s “IQ” one would expect someone to get the picture after the first umpteen dropped in. 15 individuals is a lot for a death trap that fails get anything else. And it is 15 so far. Berger & co. have really hinting how vastly bigger this find is compared to what has been dug up so far. He said possibly tens of thousands in John Mead’s interview. Unless he is completely off-base, I have a hard time imagining under 30 individuals and suspect FAR more. Berger said that cavers sent to systematically check caves have now found multiple new hominin sites and suggested one of them might top Dinaledi. If this pans out and if it is H. naledi, than any accidental explanations will be really hard to believe.

http://bluelionphotos.blogspot.com/2015/09/the-rising-star-interviews.html
http://cliffcentral.com/gareths-guests/professor-lee-berger-2/

Having H. naledi going to deep in the cave, even without burying its dead, brings up the issue of fire. Light is not a trivial issue.

If Homo naledi did not dispose of its dead then I might suggest that we really need to reconsider the notion of hominins being “rare.” At least in South Africa they are finding way too many of these things for it to be rare.

Indeed before I knew Dinaledi (or UW101 as we knew it at the time) was going to be called Homo and burial would be the explanation, it really bugged me that Rising Star seemed too good to be true. I knew UW101 had ~1550 specimens with only tiny fraction of the site worked. I also knew between UW101 and UW102 between them had at least 1724 specimens. Simple math suggests that UW102 will be a significant site in its own right*. The sheer amount of individuals likely to be present made a Malapa-like situation seem unlikely. And if it was multiple Malapas then the common ‘rare” claim is unlikely. Learning that they would called it Homo and claim deliberate body disposal to me made it no longer think of it as almost too good to be true. (Of course maybe we need to consider both not rare and disposal of the dead.)

*I have no idea if this is the site that might top Dinaledi.

    Adam Benton · 7th October 2015 at 12:41 am

    However, the paper does note that the fossils accumulated over a long period of time. Without exact dates it’s hard to say how frequently an individual would have fallen back down there; but it’s not unusual for these sorts of deposits to be palimpsests representing tens of thousands of years. You might only have had one accident a generation.

      Mike · 20th October 2015 at 8:01 pm

      One or a handful at a time dying in independent accidents over centuries would explain why so many. But it hardly solves all the problems. If it is a series of unrelated accidents then it brings up the question of why only one type of hominin seems to have these accidents. I suppose Homo naledi might have been the only hominin at that exact time, but that brings up another issue: accidents happen to nonhominins too including those which might be more at home in the caves. And accidents also tend to cause broken bones and other easily noticed damage that the seem to be missing

        Adam Benton · 20th October 2015 at 8:08 pm

        Identifying what other animals would be contemporary with this one is rather difficult since we don’t actually know how old it is (yet). As for the lack of damage, it’s worth noting that the entrance to the chamber is relatively shallow. The initial fall might not have been that dramatic, but the darkness, narrowness and general navigational difficulties associated with it may have prevented some from climbing out.

        marc verhaegen · 20th October 2015 at 8:30 pm

        H. or A.naledi (remarkably complete) fossilised in mudstone, IOW, they died in stagnant water: there’s no need for far-fetched suppositions that they were deliberately buried in caves, or even fell in caves: the caves formed long after they were fossilised in the mudstone.
        Besides, the remarkable combination of flat humanlike feet + curved hand-bones can only be explained by frequent bipedal wading + vertical climbing in swamp forests. They were no distance-runners as prof.Berger believes. And didn’t often use tools: the long thumbs are primitive for hominids, and to be expected in surface feeders of warerlilies, papyrus or frogbit, as well as in surface swimming.
        If you want to know how naledi lived, just google for illustrations at: bonobo wading. Whereas bonobos occasionally collect waterlilies, naledi did this habitually.

        Adam Benton · 21st October 2015 at 12:37 am

        As evidenced, of course, by all the phytoliths of water lilies found at the site. Oh wait….

    Todd · 7th January 2017 at 3:39 am

    Thanks for posting these links. Have been scouring the interwebs for info on the next discovery and UW-102. Each hint I find is so thought provoking. Thanks again

Jim Birch · 7th October 2015 at 12:43 am

They might have been chased into the cave by hungry animals. Hominid warfare could also be a reason to seek the last recesses of a cave and a siege situation might be a reason for overstaying, terminally.

    Adam Benton · 7th October 2015 at 12:46 am

    That’s certainly a possibility; although it need not be anything so dramatic. Modern chimps take shelter in caves just to escape the heat.

philipcoggan · 7th October 2015 at 12:41 pm

So far as I know it’s a long way from the cave entrance to the chamber. Seems a bit unlikely that anyone (or any beast) would voluntarily go so far into the dark without a very good reason.

    Adam Benton · 7th October 2015 at 1:19 pm

    Whilst the rear chamber may have always been hard to access, the chamber next to it is rather large and may have been easier to get to. The research only focused on that rear chamber. There was very little work done on the rest of the cave; so we can’t say if the modern formation is the same as it was at the time of Homo naledi.

    Besides, it can’t have been too hard to reach if they hypothesise they were able to carry a limp corpse all the way back there

Cynthia Echterling · 15th October 2015 at 9:41 pm

I recognize that many animals experience grief, but then their is the practicality of what do you do with a corpse in your living area if you are not always on the move? Do anthropologists distinguish between burying the dead, as in ritual, and disposing of the dead, as in ewww, that stinks?

    Adam Benton · 16th October 2015 at 1:10 am

    In most cases those two activities are so intertwined that it’s hard to distinguish them. For example, many cultures have a ritual or belief about how long before the dead should be buried. But this is often connected to how long before they start to decompose.

marc verhaegen · 18th October 2015 at 12:54 am

No burial, no ancestor, no runner: prof.Berger’s interpretations are anthropocentric.
From a comparative viewpoint, Australopithecus naledi is no mystery (in fact predicted, see Trends Ecol.Evol.17:212-7, 2002, google: aquarboreal), but a bonobo-like forest-swamp or wetland wader for waterlilies etc. (google: bonobo wading), who fossilised in stagnant water (mud-stone):
– The curved hand bones suggest vertical climbing in the branches above the swamps.
– The long thumbs were less for tool use than for collecting floating herbs and/or for surface-swimming.
– The broad pelvises (iliac flaring & long femoral necks) were for sideward movements of the legs (femoral abduction): for climbing and/or swimming, not for running.
– The flat humanlike feet are more flamingo- (plantigrade wader) than ostrich-like (digitigrade runner).
Lowland gorillas often wade on 2 legs in forest swamps for papyrus sedges, frogbit etc. (google: gorilla bai), but naledi apparently exploited this special niche habitually: no wonder there were no or few other macro-fauna near the naledi fossils. It was no deliberate burial (small brains): when they died, their bodies sank in the mud, and afterwards later the underground eroded to become a cave system (cf geological uplift of S-Africa).
If we go back in time towards the Homo/Pan last common ancestor, Homo shows more Pan-like features, and Pan shows more Homo-like features: what is “primitive” in Homo might sometimes be “derived” in Pan, and vice versa.
IOW, naledi, in spite of its few primitive-Homo-like features (e.g. prenatal chimps have more humanlike feet), was more likely a close relative of Pan than of Homo (google: researchGate marc verhaegen).

marc verhaegen · 21st October 2015 at 7:06 am

I have no idea how waterlilies or papyrus or frogbit or whatever aquatic herbaceous vegetation (AHV) fossilise in mudstone, but the fact alone that A.naledi skeletons fossilised in mudstone shows they died in stagnant or slowly moving waters. In any case, there’s no reason to suppose that naledi was a closer relative of ours than of bonobos. There’s no reason to believe they were better tool-users than common chimps. There’s no reason to believe they ran over to African plains as prof.Berger claims. And there’s certainly no reason to believe they buried their dead in such caves!
We know that many lowland gorillas one or two hours every day wade for AHV, and that bonobos, comon chimps & orangs do this occasionally: there’s no reason why their ancestors could not have done this more frequently (note the Pliocene was a lot hotter & wetter than most or all of the Pleistocene). In that case, flatter feet & broader hands with longer thumbs & 5th fingers, smaller front teeth etc. are advantageous: exactly what we see in naledi.
IOW, everything we know suggests naledi spent a lot of time wading in forest swamps or wetlands wading for AHV, google “gorilla bai” or “bonobo wading” illustrations.

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