Meet Homo naledi

>> The evidence for purposeful burial is basically a lack of evidence for any other means... which isn't really what you'd call conclusive. But as a null hypothesis it's at least as valid as any other without any evidence.<<

"Once you have ruled out the impossible, whatever remains, no matter how implausible, must be the truth."

A challenge is that there's a difference between purposeful placement of bodies and what we might think of as the spiritual ceremony of burial. It is quite likely that the former preceded the latter. We have as our examples such things as Homo sapiens burying their dead with ceremonial evidence, Neanderthal graves with such add-ins as red ochre paint and flower pollen that suggest some kind of ceremonial aspect, and a few higher animals such as apes and elephants who show some understanding of death.

Of particular interest to me is that, when researchers have asked signing apes about death, the answer is often something along the lines of "dark hole." An unknown, unseeable swallowing up of what was. So then, it is possible that this is hardcoded into at least some branches of the primate family, an association which may lead to burying or otherwise concealing the dead. Another possibility is that various predators cache their prey carcasses and return later, that seeds are buried by squirrels and other animals for later sprouting; and that observant hominids may have extrapolated those cyclic processes to souls. It's a perfectly reasonable leap given that almost everything in nature does cycle.

So then, we may be looking at one of the earliest roots of what has become an elaborate end-of-life ritual in most human cultures; something about as advanced on that scale as their bodies are on a physical one. When the spirit leaves, put the body into the earth. But I would look very, very closely around that cave for other clues. Did they mark on the wall? Leave rocks or sticks that might have been tools? Arrange the bodies in any way that might support deliberation rather than just dumping them? Has anyone in fact thought to check for plant pollen yet? Because if not, that urgently needs to be done, along with checking for pigments not native to the surrounding cave system. And soot, while we're at it: specifically, if there is soot, can it be traced to the earliest bones or does it appear later in the cycle?

>> That said, 15 individuals is a heck of a coincidence if they all ended up there by accident. <<

Yes, exactly. Occam's razor inclines toward deliberate placement.

>> In context, we now have nearly as many bones for that one species, as we do for the entire fossil record of every other early hominid before neanderthals. <<

That was what had me squeeing so much, really. We have a terrific representation of a species across multiple individuals -- and they are extremely similar to each other, rather than starting another argument about what's "really" a new species or whether it's just individual variation.

>> The shape of those individuals however, that's really bizarre! <<

Agreed.