Explorers discovered the bones after squeezing through a fissure high in the rear wall of the Rising Star cave, 50km from Johannesburg, before descending down a long, narrow chute to the chamber floor 40 metres beneath the surface.
The entrance chute into the Dinaledi chamber is so tight – a mere eight inches wide – that six lightly built female researchers were brought in to excavate the bones. Footage from their cameras was beamed along 3.5km of optic cable to a command centre above ground as they worked inside the cramped enclosure.
The leaders of the National Geographic-funded project believe the bones – as yet undated – represent a new species of ancient human relative. They have named the creature Homo naledi, where naledi means “star” in Sesotho, a local South African language. But other experts on human origins say the claim is unjustified, at least on the evidence gathered so far. The bones, they argue, look strikingly similar to those of early Homo erectus, a forerunner of modern humans who wandered southern Africa 1.5m years ago.
“We’ve found a new species that we are placing in the genus Homo, which is really quite remarkable,” said Lee Berger, a paleoanthropologist who led the work at the University of Witwatersrand in Johannesburg. He described the slender, small-brained creatures as “long-legged”, “pinheaded” and “gangly”. The males stood about 5ft, with females a little shorter.
Measurements of the bones show that the creature has a curious blend of ancient ape and modern human-like features. Its brain is tiny, the size of a gorilla’s. Its teeth are small and simple.
The thorax is primitive and ape-like, but its hands more modern, their shape well-suited to making basic tools. The feet and ankles are built for walking upright, but its fingers are curved, a feature seen in apes that spend much of their time in the trees. The findings are reported in two papers published in the online journal eLife.
The Dinaledi chamber has been visited by explorers in the past, and the soft sediments in which the bones were found have been badly disturbed. Because the remains were not encased in rock, Berger’s team has not been able to date them. They could be 3m years old, or far more modern.
No other animals were found in the chamber that might hint at when the human relative got there.
“If this is an ancient species, like a coelacanthe, that has come down through time and is only tens of thousands, or hundreds of thousands of years old, it means that during that time we had a complex species wandering around Africa, perhaps making tools. That would make archaeology very difficult, because we aren’t going to know who made what,” Berger said.
Where the bones were discovered
The conclusion is not widely accepted by others. “Intentional disposal of rotting corpses by fellow pinheads makes a nice headline, but seems like a stretch to me,” said Jungers. Zollikofer agrees. “The ‘new species’ and ‘dump-the-dead’ claims are clearly for the media.
None of them is substantiated by the data presented in the publications,” he said.
Hawks is open to other explanations, but said that disposal made sense. “The evidence really tends to exclude the idea that they entered the chamber one at a time, alive, over some time, because
we have infants, small children, and very old adults who would almost certainly not have managed
to get into this chamber without being deposited there.”