If you want to know where humans come from, there are some pretty big gaps in the family tree. You'd think the major discovery of a whole new human ancestor could help fill in one of those gaps, but it turns out that our latest relative, Homo naledi, is so unusual it just might create a whole new branch of the family tree instead.
Findings on the extinct hominin -- which were published in the journal eLife Thursday -- are nothing short of historic, with over 1,500 specimens from 15 Homo naledi individuals excavated from an underground cave in South Africa. (The name is a tip of the hat to the name of this cave, Rising Star -- "naledi" means star in the local Sotho language.) According to the paper, the geological age of the fossils have yet to be determined.
"We know they have the character(istic)s of an early member of the genus Homo...we can see that we would place them right at the base of the lineage that leads to us," American paleoanthropologist Lee Berger says in the below clip from an upcoming National Geographic/Nova documentary. "We've never seen a nonhuman that shares so many primitive and yet sometimes advanced characters. Tiny brain, curved fingers, but a generally humanlike hand, long legs and a human foot."
The findings on Homo naledi are laid out in wonderful detail at National Geographic. The story starts with Berger and his strong conviction that some important part of the story of human evolution lay buried in the soils of South Africa. Over the past few decades, Berger made some small finds and a few major ones that were published and hinted that he was on the right track, even if many others dismissed his interpretation of them.
Then, a few years ago, recreational cavers tipped off Berger that they had found a section of Rising Star cave outside Johannesburg only accessible through a few incredibly tight passages that were littered with bones. Berger mounted an expedition, recruiting a handful of slender scientists willing to spelunk into and document the site and then recover the bones and fossils for study.
But while this new species appears clearly humanlike in many ways, just when you think it might be the missing link in our evolution, it also turns out to be, well...pretty weird, too.
Our ancient relative's curved fingers may have been ideal for climbing trees, which points to more primitive apelike creatures, but then there's also the mystery of how such a large collection of bones came to rest in a relatively inaccessible location.
"Homo naledi was doing something that until this moment we thought was unique to modern humans -- that is, deliberate disposal of the dead," Berger surmises. "If this hypothesis holds true, that's an extraordinary thing."
Everyone's got a funky branch to their family tree it seems; perhaps this makes it official for the entire species.
The documentary will premiere on US TV channel PBS on September 16 (or you can watch it online starting Thursday).