“Homo naledi is an extraordinary new discovery, both in terms of the unique combination of features found in its skeleton and its inferred behavior,” said William Harcourt-Smith, a co-author on the paper who is a resident research associate in the Museum’s Division of Paleontology and an assistant professor at CUNY’s Lehman College.
The initial discovery was made in 2013 in a cave known as Rising Star in the Cradle of Humankind World Heritage Site, some 50 kilometers (30 miles) northwest of Johannesburg, South Africa, by University of the Witwatersrand scientists and six cavers who are being called “underground astronauts.”
H. naledi was named after the location: “naledi” means “star” in the local Sesotho language. The finds were announced earlier today by the University of the Witwatersrand, the National Geographic Society, and the South African National Research Foundation and described in two papers published in the journal eLife.
Perhaps most remarkably, the location and nature of the discovery has led the researchers to conclude that this hominin deliberately disposed of bodies—a form of ritualized behavior previously thought to be unique to modern humans.
The fossils—which include remains of infants, children, adults, and elderly individuals—were found in a room deep underground that the team named the Dinaledi Chamber, or “Chamber of Stars” in Sesotho. That room has “always been isolated from other chambers and never been open directly to the surface,” said Paul Dirks of James Cook University in Australia, lead author of the accompanying eLife paper on the context of the find. “What’s important for people to understand is that the remains were found practically alone in this remote chamber in the absence of any other major fossil animals.”
The team notes that the bones bear no marks of scavengers or carnivores or any other signs that non-hominin agents or even natural processes, such as moving water, carried these individuals into the chamber.
“We explored every alternative scenario, including mass death, an unknown carnivore, water transport from another location, or accidental death in a death trap, among others,” said team leader Lee Berger, research professor in the Evolutionary Studies Institute at the University of the Witwatersrand and a National Geographic Explorer-in-Residence, who led the two expeditions that discovered and recovered the fossils. “In examining every other option, we were left with intentional body disposal by Homo naledi as the most plausible scenario.”
So far the team has recovered more than 1,500 fossil elements belonging to at least 15 individuals, a wealth of fossil material that is expected to shed new light on the origins and diversity of our genus. A small fraction of the fossils are believed to remain in the chamber.
“With almost every bone in the body represented multiple times, Homo naledi is already practically the best-known fossil member of our lineage,” Berger said.
The new research shows that an average H. naledi stood about 5 feet tall and weighed about 100 pounds. With a tiny brain—about the size of an orange—a slender body, ape-like shoulders, and curved fingers that demonstrate climbing capabilities, H. naledi looks like one of the most primitive members of our genus. But it also had some surprisingly human-like features.
Its feet, for instance, are “virtually indistinguishable from those of modern humans,” said Harcourt-Smith. This, combined with its long legs, suggests that the species was well suited to long-distance walking.
The discovery is featured as the cover story of National Geographic October 2015 issue.
The find is also detailed in the NOVA/National Geographic Special “Dawn of Humanity,” premiering September 16, 2015, at 9 pm ET on PBS.