by NEW YORK (AP) — An ancient human cousin may have buried his dead and carved symbols into cave walls, surprising findings for a small-brained creature.
Fossil remains of the species – called Homo naledi – were discovered a decade ago in underground caves in South Africa. Now researchers say they’ve found evidence that the species was capable of complex behaviors that have so far only been seen in humans with larger brains.
“We’re facing a remarkable discovery here” for a species with brains one-third the size of humans, said anthropologist Lee Berger, who led the research funded by the National Geographic Society, where he now works.
Berger and colleagues detail their findings in studies posted online Monday. The research has not yet been peer-reviewed, and some outside scientists think more evidence is needed to challenge what we know about how humans evolved their complex thinking.
“There’s still a lot to discover,” said Rick Potts, director of the Smithsonian’s Human Origins Program, who was not involved in the study.
H. naledi is a fairly new addition to the hominin family tree, which includes our direct ancestors and other extinct bipedal relatives. Berger and his team announced the species in 2015, after a tip from local cavers led them to the Rising Star cave system near Johannesburg, where they discovered fossils of at least 15 individuals who lived about 300,000 years ago.
These creatures shared some traits with modern humans, such as legs made to walk upright and hands that could work with objects, said University of Wisconsin-Madison anthropologist John Hawks, a member of the research team. But other features looked older, including their cerebellum.
In recent years, team members have ventured back into the caves, a tricky descent through tight underground spaces. What’s down there shows the species in a new light, they reported.
One of the new studies details what researchers believe were intentional burials. The team discovered fossilized remains of adults and children in shallow holes in the ground, their bodies in fetal positions.
Another study describes a series of markings carved into the cave walls, including geometric patterns and hatched lines.
“This is something that takes a lot of time and effort to do,” said Berger, who led the initial research at the University of the Witwatersrand in Johannesburg.
All of this behavior would be surprising for a creature whose brain is closer in size to that of an ape than to a human, experts said.
Decades ago, we thought Homo sapiens were the only ones who could figure out how to use fire, bury their dead or create art, said Chris Stringer, an expert in human evolution at London’s Natural History Museum, who was not involved at the investigation.
Since then, we’ve learned that other groups like Neanderthals also led complex lives. But those species still had big brains — unlike H. naledi, whose burials would raise further questions about human evolution, Stringer said.
Scientists have not yet been able to determine how old the carvings are. So Potts said the current evidence can’t say for sure whether H. naledi was really the one who created the symbols, or whether some other creature — perhaps even H. sapiens — got there at some point.
For study author Agustin Fuentes, an anthropologist at Princeton University, the evidence of H. naledi takes the focus away from brain size.
“Big brains are still important,” Fuentes said. “They just don’t explain what we thought they explained.”
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