In an unprecedented discovery, 15 partial skeletons have been unearthed from deep inside a cave in South Africa. Dubbed homo naledi, researchers say that these old "human-like" fossils suggest the discovery of a new species that could change our ideas on human evolution. But some remain skeptical.
In a study published today in the journal eLife, researchers describe finding the skeletons of all different age groups and genders in the Rising Star cave in the Cradle of Humankind—a place which has already produced an abundance of hominin fossils (a group consisting of modern and extinct human species, and immediate human ancestors)—in South Africa.
"During a relatively short excavation, our team recovered an extensive collection of 1550 hominin specimens, representing nearly every element of the skeleton multiple times," write the researchers in their paper.
"With almost every bone in the body represented multiple times, h. naledi is already practically the best-known fossil member of our lineage," Lee Berger, a paleoanthropologist at the University of Witwatersrand in Johannesburg who headed up the expedition, said in a press statement.
The bone measurements suggest a mix of ancient apelike and modern human qualities, with h.naledi possessing extremely human-like legs and feet, tiny brain, simple teeth, and hands with curved fingers—capable of making basic tools. The males measured around 1.5m while the females measured around 1.45m. The surprising discovery—which Berger asserts was "never seen before in the fossil record" in a YouTube clip—was first uncovered back in October 2013 in an expedition funded by the National Geographic.
But while the researchers assert they've uncovered a new human species, others from the paleoanthropology community say that the paper lacks enough evidence to back up that claim.
"If you look closely at the data that has been published it doesn't really support the claims of a new species," Christoph Zollikofer, a paleoanthropologist at Zurich University in Switzerland, told me. "The second problem is that there's no geological date."
"This discovery is amazing."
As the bones have not been given an exact geological age, some think that homo naledi could be from the homo erectus group—which roamed South Africa roughly 1.9 million years ago.
"We know quite a bit about homo erectus, and what we see at this Dinaledi site nicely fits into the variations seen in early homo erectus," said Zollikofer.
While there's still no concrete evidence to prove that h. naledi is a new human species or a member of homo erectus, Berger argued in a report by New Scientist that h. naledi's pelvis and shoulders make it seem like it belongs to the "apelike Australopithecus which appeared in Africa about four million years ago." Yet its humanlike foot makes it look like a member of the human species, which "appeared just 200,000 years ago."
Though h. naledi's exact age and ancestry is still a mystery, it's still an epic find.
"This discovery is amazing," said Zollikofer. "We as paleoanthropologists are happy about every single specimen because they're so rare, and getting them in large quantities—more than one individual from a given site—is just wonderful."