Watch the real-life “bone collector” in action. Biological anthropologist and National Geographic Emerging Explorer Marina Elliott ventured a hundred feet deep into an ancient cave, at times squeezing through passages only eight inches wide, to recover the remains of what turned out to be a newly discovered, extinct human ancestor.

Working with expedition leader and National Geographic Explorer-in-Residence Lee Berger, Elliott led an excavation team into Rising Star Cave, where cavers had previously come across unidentified bones. Elliott expected a relatively quick job of retrieving fossils belonging to a single individual but “when I first started looking into that space, my headlamp was picking up flashes of bone just here and there and everywhere,” she recalls. “We recovered around 1,500 fragments from that first expedition, in an area smaller than a child’s sandbox.” Upon examination, the scientists determined that the fossils belong to the human genus—but not to a species already known to science.

The discovery of our new but extinct family member Homo naledi—named after Rising Star Cave, as naledi means “star” in a local South African language—is turning our understanding of our past on its head just a bit. Homo naledi appears to be one of the most primitive known species in the human genus, with a small brain and ape-like features. But H. naledi also has some more humanlike features that distinguish it from any other known early human ancestors. It has curved fingers good for climbing, feet and legs suited for long-distance walking, and H. naledi may have even engaged in ritualized behavior.

“There’s a lot of books about human origins and human evolution. For a long time, I think we thought we sort of wrapped it up. What Homo naledi has done is kind of forced a whole scale rethink of that. The family tree that we always think about, and have been adding little twigs and branches to along the way, actually may be a lot bushier than we ever really realized. In fact, that whole tree analogy may not be a good analogy at all. A lot of these branches actually rejoined each other and became something else. The relationships of past species and past populations is a lot more complicated than we had originally assumed.

“We have 15 individuals, ranging in age from neonates to older adults. The whole assemblage is something that we didn’t think we’d ever get in paleoanthropology. We’re used to dealing with very small scraps of material. What this is doing is a real wake up call to the discipline,” says Elliott.

But how did so many of our ancestors end up in the underground labyrinth? “Really, there’s no other explanation than they were deliberately deposited there. Whether they were dragged all the way in or whether they were sort of tumbled in is another question,” Elliott says, musing on the possibility of ritualized behavior. It’s actually a lack of evidence that leads scientists to believe our ancestors were purposely placed in Rising Star. “We have no buck, or deer, no ungulates in there, not a baboon bone, not a porcupine, none of these species that often frequent caves in the first place, are in there. We have no signs of carnivore activity on the bones. Even if there had been an opening from above, such as a sink hole, there are very few sink holes that selectively kill only one species.” Elliott explains.

While Homo naledi may be the discovery of a lifetime—or perhaps, many lifetimes—Rising Star may hold yet more clues to our ancient past. “The space that we excavated is only maybe a tenth of the surface of that chamber floor,” says Elliott. “There’s a lot more material to recover. It’s going to be decades of work.” Elliott is leading those ongoing excavations.

Marina Elliott delicately excavates a fragile skull found inside Rising Star Cave.

Marina Elliott is a grantee of National Geographic’s Expeditions Council . To learn more about the science and exploration supported by the nonprofit National Geographic Society, visit natgeo.org/grants.

VIDEO CREDITS:

VIDEO PRODUCER/EDITOR: Nora Rappaport

SERIES PRODUCER: Chris Mattle

ASSOCIATE PRODUCER: Elaina Kimes