Homo naledi is the big news in paleoanthropology right now.
Naledi is an ape-man, with some features close to modern humans and others honestly more like a chimpanzee. Or a gorilla. Including the brain, which is about the same size as that of a, yup, gorilla.
No offense to our cousins, but gorillas aren't nearly as smart as we are. Now, some researchers think Homo naledi is actually a racial variant of homo erectus. (But then, lines between species can be funky anyway).
And right now, we haven't come up with any explanation for how the bodies ended up in a cave that contains no remains of any other species other than deliberate burial. Gorillas and chimpanzees both demonstrate behavior that looks like mourning - but so do dogs and horses. Both species sometimes do death vigils - staying with a body for a period of time. Elephants are even more known for this behavior and have also been seen to cry and, unlike any other species but us, interact with the dead. Elephants will go back to the skulls of dead companions and pick them up - behavior not uncommon amongst humans. In fact, they are the only species other than humans to perform funeral rituals - covering carcasses with branches and sometimes taking the tusks and putting them in a specific location. (Elephants have also been recorded covering or attempting to cover dead...or in some cases merely unconscious...humans).
So, we have two living species that consistently perform funereal rites - humans and elephants.
Did naledi? We can't be sure, but it looks like they did. Furthermore, to get to the cave, even if it was easier to get there back when they lived, they would have had to go through pitch darkness.
And none of the bones in the cave showed signs of predation. Not one. It's more normal to find 6 to 10 percent of bones showing tooth damage from being killed or injured by predators. Early hominids were prey animals to at least some point. (Some people argue they were primarily predators, but that forgets that an animal can be both).
If these hominids were going into a dark cave to do funerary rites and less subject to predation then that points to a very reasonable hypothesis:
They had fire.
Chimpanzees will cook food if humans provide the fire, but they don't know how to create it themselves.
A bonobo (bonobos are the most intelligent apes other than us) named Kanzi has been taught to build a fire and toast marshmallows.
But despite rumors, only humans master fire. It is the one thing that makes us unique. Other animals might take advantage of fire provided to them. Other animals make tools, communicate in vocalizations.
Only humans master fire.
But the scientists who discovered naledi insist these hominids - whether they're a new species or just a new race - are not human. Their brains aren't big enough.
I find that somewhat hard to accept.
But here's the other thing that is fascinating.
If it's true that naledi has fire, then this indicates the mastery of fire came before the great leap in intelligence.
What if we did not become smart and then learn to use fire but rather learned to use fire and had to become smart to control it? What if technology comes before intelligence?
There's already some indication that manipulative appendages come before intelligence, but technology? (And yes, cetaceans are very smart and possibly sentient without technology, but I think if we ever learn to communicate with them properly we'll discover that they have a very different intelligence from us).
It's something to consider - because it has implications for intelligent life elsewhere. (And, of course, for worldbuilding).