South African paleoanthropologist and National Geographic explorer Lee Berger described the discovery of soot-covered walls, charcoal fragments, burnt antelope bones and rocks arranged in hearths in the Rising Star cave system, where nine years earlier the team had discovered the bones of a new member of the human family, Homo naledi.
Control of fire is considered a crucial step in human evolution, providing light for navigating dark places, enabling nocturnal activity and leading to cooking of food, and subsequent increase in body mass. When exactly the breakthrough occurred, however, has been one of the most contentious questions in all of paleoanthropology.
“We’re probably looking at the culture of another species,” said Berger, who forgoes scientific convention by reporting the findings not in a peer-reviewed journal, but in a press release and a Carnegie Science conference at the Martin Luther King Jr. Memorial. Library in Washington on Thursday. In an interview with The Washington Post, Berger, a professor at the University of the Witwatersrand in Johannesburg, said official documents were being reviewed and added, “A series of major findings will be released over the next month.” .
He pointed out that his team’s discoveries this summer answer a crucial question raised when the initial hoard of 1,500 fossil bones was announced: how did this ancient species find its way into a cave system about 100 to 130 feet underground, a place that is devilishly hard to reach and, in his words, “horrifyingly dangerous”?
The research team now believe that H. naledi used small fires in chambers throughout the cave system to light up. Berger based the claim in part on his personal journey through the cave’s narrow passages, which required him to lose 55 pounds.
Moreover, he argued that the use of fire by a human parent with a brain slightly larger than a large orange upsets the traditional story of our development. For years, experts have described evolution as “a ladder” that rose ever higher toward species with bigger brains and greater intelligence, while letting smaller-brained species perish.
But evidence has been mounting that the process may have been more complicated than expected, an opinion that would be reinforced if indeed this smaller-brained contemporary from the start Homo sapiens was advanced enough to use fire.
Berger’s lecture, complete with photographs of the cave but lacking carbon dating and other traditional scientific methods, drew criticism, as did some of his earlier claims about H. naledi fossils.
“There is a long history of claims about the use of fire in South African caves,” said Tim D. White, director of the Center for Human Evolution Research at the University of California, Berkeley, who is a former critic of Berger. “Any claims about the presence of controlled fire will be met with some skepticism if they come from a press release rather than data.”
Previous reports of mankind’s early use of fire, even those accompanied by scientific evidence, have proven controversial. In 2012, archaeologists using state-of-the-art technology reported “unambiguous evidence in the form of burnt bones and ash plant remains that fires occurred in Wonderwerk Cave” in South Africa around 1 million years. Critics have questioned this age estimate, and scientists have revised the date to at least 900,000 years old after using a complex technique called cosmogenic nuclide dating.
White said rigorous studies must date both the fire evidence and the H. naledi bones if Berger’s team is to demonstrate that the two are from the same time period. Further studies must show not only the presence of fire, but its controlled use. Testing should establish that the material believed to be soot is actually soot and not discoloration caused by chemicals or other factors.
Berger acknowledged that one of the main challenges he and his colleagues will face will be dating the materials they have found. So far, they’ve said the H. naledi bones date to between 230,000 and 330,000 years ago, though Berger stressed that these dates shouldn’t be considered the first or last appearance of H. naledi. the species.
White appeared very skeptical of the lack of stone tools found in the caves. He said archaeologists would expect to find thousands of stone tools in a place where human relatives used fire for light and cooking.
“I will tell you at this point that there are no stone tools that we have found in the presence of an outbreak,” Berger said in the interview. “It’s a strange thing.” Nonetheless, he told the audience at the Carnegie Science conference, “Fires don’t start spontaneously 250 meters away in a damp cave, and animals don’t just wander into the fires and get burned.”
He said stone tools were found in the general landscape outside the caves. He also pushed back against criticism that what the team found did not constitute evidence of a former home.
“We found dozens of homes, not just one,” Berger said when asked about the evidence during the interview. “It’s 100%. There’s no question about it. … We’re now entering a phase where it’s going from just bones to a rich understanding of the environment they lived in.
Berger had already been the subject of controversy when the H. naledi discovery was initially announced., when he suggested that these ancient relatives deliberately used the caves as a place to deposit their dead. Despite the debate, Berger repeated the assertion several times during the conference, acknowledging that it was “perhaps not very well received by most of the academy”.
Other researchers said that while there is still a lot of testing to do, the latest findings from Rising Star are impressive.
“I think it’s great. It sounds very compelling,” said Richard W. Wrangham, professor of biological anthropology at Harvard University and author of the 2009 book “Catching Fire: How Cooking Made Us Human.”
“Of course, it’s fascinating because of the small and generally mysterious nature of these people.”
Wrangham said that when the discovery of H. naledi was announced he was discussing the dark caves where the bones were found with one of Berger’s colleagues and remarked: “Surely that must mean they had light.”
However, Wrangham said he was puzzled on one point: “How did they stand the smoke? Was there a draft that blew the smoke out of the cave? »
Wrangham said he was prepared to take Berger at his word on the use of fire, based on early evidence. He said the strongest evidence for early control of fire comes from an archaeological site in Israel called Gesher Benot Ya’aqov, where experts say early human relatives used fire to cook fish ages ago. about 780,000 years old.
During the talk, Berger also shared vivid descriptions of some of the 50 H. naledi individuals the team found.
He described the fossil bones of a hand “wrapped in a mortal grip”; the skull of a foundling sitting atop a shelf in the rock; and the skeleton of another child tucked away in an alcove in one of the bedrooms. The dramatic footage required an equally dramatic journey through a dolomite cleft that narrows to just seven inches and requires extreme contortion of an explorer’s body.
“You’re basically kissing the ground,” said Keneiloe Molopyane, a 35-year-old researcher at the South African University’s Center for Exploring Deep Human Journey. The explorers, she continued, emerge on a perilous ridge about 65 feet above the cave floor. Inside, it’s dark, with “bats hissing near you on either side.” If you fall, you belong in the cave.
The reward, however, is a feeling Molopyane remembers vividly during his first descent into the cave system: “Oh, my God. I’m the first person to see these remains in I don’t know how many thousands of years, and now I’m touching them.
Berger said about 150 scientists from around the world are participating in the effort to excavate, date and study the remains and artifacts found in the Rising Star cave system.
Asked to speculate on the interactions and possible conflicts that may have taken place between H. naledi and H. sapiens, Berger replied: “Whatever you just asked, in the next 36 months we will have answers.
