When famed palaeoanthropologist Lee Berger challenged the history of human evolution in 2015 by raising the idea that Homo naledi, a small-brained predecessor of humans, buried their dead at least 100,000 years before Homo sapiens, the evidence to support this controversial theory was limited.
But eight years later the excavation of the Rising Star cave system, in the Cradle of Humankind, has yielded compelling evidence to back up the claim that the Stone Age Homo naledi likely had “meaningful” rituals — such as burying their dead in oval pits and carving symbols on the nearby cave walls, which also reportedly bear traces of fire.
Releasing their latest findings, yet to be peer-reviewed and confirmed, Berger said on Monday night: “These recent findings suggest intentional burials, the use of symbols and meaning-making activities by Homo naledi.
“It seems an inevitable conclusion that in combination they indicate that this small-brained species of ancient human relatives was performing complex practices related to death. That would mean not only are humans not unique in the development of symbolic practices but may not have even invented such behaviours.”
The scientists reported that the specimens they unearthed within the Rising Star cave system, in the Cradle of Humankind, were the “most ancient internments yet recorded in the hominin record”, laying out the details in three papers available on BioRxiv. The first bones of Homo naledi were found there 10 years ago.
Team geologist Dr Tebogo Makhubela, who has worked in and on the Rising Star cave system for the past decade, said that it has been exciting to work with an international team that has discovered so much about a primitive “species that [people] didn’t know existed”.
Descending about 30m underground through a labyrinth chute system, was physically and mentally demanding, he said. “I have been down there about 20 times and every time it is a challenge,” said Makhubela, who has been stuck down in the cave system, though he works mostly in a lab at the University of Johannesburg.
This would mean not only are humans not unique in the development of symbolic practices but may not have even invented such behaviors.
— Paleoanthropologist Lee Berger
“People ask how Homo naledi, with a third of our brain, could manage to get down there. but they were probably better at this than us with their curved fingers and toes for climbing trees.”
Berger and his team discovered the first Homo naledi fossils in the Dinaledi chamber in 2013, and in 2022 he had to lose about 20kg to get through the chamber himself as the excavation leader.
Digging into the cave floor millimetres at a time over the past decade, the team have found several specimens in the Unesco world heritage site.
Princeton University anthropology professor Agustín Fuentes said: “To be inside the caves — inside the world of Homo naledi — is not only a life-changing adventure, but what we’ve uncovered forces us to rethink a whole set of assumptions about hominins and human evolution.
“Much of what we assumed was distinctively human, and distinctively caused by having a large brain, may not be either of those things. Burial, meaning-making, even ‘art’, could have a much more complicated, dynamic, non-human history than we previously thought.”
National Geographic explorer-in-residence Berger’s fellow explorers included Dr Keneiloe Molopyane and Fuentes. The team found depressions in the chamber’s floors and the bones of adults and at least four children in foetal positions in these hollows.
Engraved symbols and etchings, resembling geometric shapes and cross-hatchings, were visible on smoothed out ancient dolomitic walls and seem to have been created by a sharp tool, the team reported. They estimated them to be 241,000 to 335,000 years old, but further testing is needed on them.
Neanderthals (Homo neanderthalensis) created symbols almost 60,000 years ago and early Homo sapiens about 80,000, scientists estimate.
The latest papers will be published in eLife reviewed Preprints and Berger’s new book, Cave of Bones: A True Story of Discovery, Adventure and Human Origins, will be released in August.
Next month Netflix will air a four-part docuseries titled UNKNOWN: Cave of Bones on this quest.
Makhubela said the evidence that Homo naledi exhibited complex behaviour is there. “Our continuing work is slowly uncovering this, it is very slow and very sensitive, but it is coming together.”
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