New Human Ancestor, Homo Naledi, Discovered in South African Caves

Homo naledi
The cranium (A and B) and jaws of Homo naledi, which could be the oldest ancestor to modern Homo sapiens yet discovered. John Hawks/eLife

Fifteen partial skeletons of a new human-like species have been discovered in South Africa in what has been described as a "bridge" between humans and their primate ancestors. The new species has been named Homo naledi.

Scientists made the discovery in what they called a "burial chamber," locked away in the Rising Star cave system, located in the Cradle of Humankind World Heritage Site about 30 miles northwest of Joannesburg, South Africa, BBC reported. (Naledi means "star" in the local Sotho language, according to National Geographic.)

The discovery yielded fifteen skeletons, including both male and female subjects of a range of ages, from children to elderly people. Researchers have recovred over 1,550 bones and bone framents already, and say there are many more to come in the chamber. In their study, published in the journal eLife on Thursday, the research team said it was the biggest single discovery of its type in Africa.

"I saw something I thought I would never see in my career," Lee Berger, a paleoanthropologist at the University of Witwatersrand in Johannesburg and leader of the study, told the BBC. "It was a moment that 25 years as a paleoanthropologist had not prepared me for."

Modern humans belong to the Homo genus, which is believed to be up to 2.5 million years old. Berger believes Homo naledi could be the first species of the genus and could have lived in Africa up to three million years ago. The discovery could reveal new details about the evolution of humans from primitive, bipedal primates to the ancestors of the modern species.

The well-preserved state of the remains will enable the researchers to learn "everything about this species," Berger said. Homo naledi have hands which are a very similar shape to those of modern humans, while arches in the feet suggest the ancient species walked on two feet.

homo-naledi-hands
Researchers say the proportions of digits on the hands of Homo naledi are very human-like. John Hawkes/eLife

These human-like features stand in sharp contrast to the species' trunk, shoulder and pelvis, which are more typical of the Australopithecus genus, an ancient ancestor of hominids which lived between 5.3 million and 11,700 years ago. Lucy, the skeleton discovered in Ethiopia in 1974, is the most famous representative of these more ape-like primates.

The study says that Homo naledi probably averaged about 5 feet in height and wrighed, on average, 100 pounds. Their braincases, according to the study, tend to be relatively small, however. Males averaged around 34.2 cubic inches, and females averaged 28.4 cubic inches—less than half the size of normal modern human braincases.

homo-naledi-full-skeleton
This image shows a complete "skeleton" of 'homo naledi,' a composite of elements that represent multiple individuals. This view is foreshortened; the table upon which the bones are arranged is approximately 50 inches wide for scale. eLife

However, this doesn't mean they weren't capable of very human-like thought and behavior. The fact that the remains were found in what appears to be a chamber for the dead also suggests that the species were capable of ritual behavior such as burials—a social behavior that had previously been associated only with humans living in the past 200,000 years.