Debate About New Human Species Found in South African Cave

Scientists from the University of Witwatersrand in Johannesburg, South Africa have differing theories on fossilized bones found in Rising Star Cave.

Rising Star Cave, part of the Cradle of Humankind World Heritage Site, is 30 miles from Johannesburg in the Gauteng province. The area features 123,550 acres of hilly grassland and is known for a network of caves where 40% of known hominid fossils have been excavated.

In the Dinaledi chamber with its pure white rocks, the hominid species Homo naledi was discovered. Spelunkers happened upon the fossilized remains among dripping stalactites and jagged rocks in 2013. The controversy is about how the bones appeared in the remote, 30-foot long by only a few feet wide cramped chamber. Today, it is only accessible by climbing down a steep 40-foot chute.

Shortly after the fossils were discovered, Lee Berger, professor and paleoanthropologist at the University of Witwatersrand led a team to excavate the fossils. He recruited small, young women who would fit in the tight cave to film, photograph and document their findings while he directed the operation on the surface. They recovered 1,550 bones.

In September of 2015, Dr. Berger said of the findings,

The species of non-human hominin was deliberately disposing of its dead. Taking a dangerous journey into this deep chamber to place its dead or drop its dead into a place that was inaccessible.

Up until his study, it was thought that only modern humans reverently disposed of their dead.

New research suggests that the bones were not deliberately placed but were swept into the cave chamber by water. Analysis of the sediment and rock reveals that there was never a direct opening to the underground chamber from above. Some of the bones were scattered and most of the remains show signs of erosion.

Dr. Aurore Vale, an evolutionary biologist at the University of Witwatersrand theorizes that water carried the bones/body parts deeper into the cave to where they were found. She also points out to modifications to the fossilized bones, perhaps created by beetles and African land snails, creatures that would have lived closer to the entrance of the cave and outdoor light. Her study suggests that the bones may have originally been located closer to the surface and were buried in a cave collapse or swept in by water.

She says,

This raises serious questions about the veracity of the hypothetic that fresh complete bodies were deliberately disposed into the Dinaledi chamber.

She is one of many anthropologists who have expressed doubts over Berger’s theory. Another is Professor Francis Thackery, an evolutionary biologist also at the University of Witwatersrand, who says,

To carry these 15 carcasses in complete darkness through a very narrow route in complete darkness raises questions. I think in the past there could have been a second entrance. Dotermite rock that is quite soluble in geological time. There could have been a second opening and there was a collapse and 15 individuals had been trapped.

In studying the bones, Professor Thackery found black spots on them that he believes are marks of manganese dioxide left by lichen. This suggests that the bones may have been in a part of the cave closer to an illuminated entrance.

Professor Berger defends his theory:

Whatever the entrance was, it would have to conform to the same restrictive criteria – only allowing one species of animal in over time, while not allowing externally derived sediments into he cave and restricting access to predators and scavengers. So if there were another entrance, it would have to be nearly if not equally as restrictive as the one we use now. I can understand the discomfort --- we have spent more than a hundred years in this field seeing the unique behaviors of humans as being due to a big brain. It’s not going to be easy to convince everyone that complexity is not driven by a single organs size alone --- despite the evidence.

He is citing the small, orange-size brain found in Homo naledi. The species is unique in that it has both bipedalism (walking upright on two feet) and climbing adaptations (long, curved fingers and shoulder blades positioned low behind the chest adapted for climbing).

If these five-foot tall creatures could reveal the secret to their appearance in the cave, the mystery would be solved once and for all.