Carl Zimmer reports:

In 2015, scientists reported an astonishing discovery from deep inside a South African cave: more than 1,500 fossils of an ancient hominin species that had never been seen before.

The creatures, named Homo naledi, were short, with long arms, curved fingers and a brain about one-third the size of a modern human’s. They lived around the time the first humans were roaming Africa.

Now, after years of analyzing the surfaces and sediments of the elaborate underground cave, the same team of scientists is making another splashy announcement: Homo naledi — despite their tiny brains — buried their dead in graves. They lit fires to illuminate their way down the cave, and they marked the graves with engravings on the walls.

Lee Berger, a paleoanthropologist at the University of Witwatersrand in Johannesburg and the leader of the project, said that the discovery that a small-brained hominin did such humanlike things was profound. It suggests that big brains are not essential for sophisticated kinds of thinking, he said, such as making symbols, cooperating on dangerous expeditions or even recognizing death.

“This is the ‘Star Trek’ moment,” he said. “You go out, you meet a species, it’s not human, but it’s equally complex to humans. What do you do? That’s our moment, right now.”

But a number of experts on ancient engravings and burials said that the evidence did not yet support these extraordinary conclusions about Homo naledi. The cave evidence found so far could have a range of other explanations, they said. The skeletons might have been merely left on the cave floor, for example. And the charcoal and engravings found in the cave might have been left by modern humans who entered long after Homo naledi became extinct. [Continue reading…]