Modesto professor part of team picked to probe Rising Star find in South Africa

Untold millenia ago, primates that walked upright and had larger brains than chimps lived in a community and buried their dead. Cave explorers in South Africa found the hidden burial chamber in 2013, opening the door for a worldwide effort to piece together the extinct primates’ place in human evolution. As experts gathered from around the globe, they called in a specialist in juvenile primates, a professor at Modesto Junior College.

“They recruited me,” said anthropology professor Debi Bolter, to lend a hand identifying the infant-to-adolescent bones. She spent a month in 2014 at the University of the Witswatersrand in Johannesburg, among 40-plus scientists brought together to sort and catalog more than a thousand fragments. “It’s pretty incredible,” she said with a shake of her head.

A picture hangs on her wall of herself with the team, standing in the fossil vault lined with shelves of skulls and bones. But she has not been able to speak of the find until now, when the research was announced after exhaustive academic review. A NOVA special detailed the find.

“It was like science summer camp. It was pretty fun actually,” she said.

Bolter did not get to go into the chamber itself. National Geographic described the site as being at the bottom of “a vertical, pitch-dark, seven-inch-wide passage,” which comes at the end of a narrow, 100-foot tunnel.

“They have to be really tiny people to go in there,” Bolter said, adding that the research team advertised for petite female spelunkers with archaeological backgrounds. “I spoke with one of the women. She said the hardest part was the Superman crawl.” Running water in the narrow tunnel meant crawling the length of it, head lifted as high as possible.

No scavenging animals reached the dark, secluded spot, allowing the bones of at least 15 individuals – named Homo naledi by researchers – to be recovered, a find that dwarfs previous hominin discoveries. There is only one Lucy, after all, and that skeleton of an upright-walking primate was likely from a different branch of the evolutionary tree, Bolter said.

The bones ranged in age from infant to elderly, and the brains would have been roughly one-third the size of human brains today. Where and when they fit in the evolutionary path is what fascinates scientists. Carbon dating cannot track anything this ancient, likely more than a million years old.

The depth and difficulty of reaching the cave dark zone meant it was not a place frequented by the living, but burial had been thought to be a relatively modern invention. “We thought that’s what made us who we are,” Bolter said.

She sorted juvenile bones into age classes – infant, child and adolescent – but said the years do not coincide with the protracted growth cycle of humans, another evolutionary mystery.

“When did we have a childhood?” Bolter asked, noting that humans are alone in living so much of their life before reaching maturity. “We take a longer time to grow up.” Finding youth bones among fossils is rare, she said. “We almost never have them.”

The work she started in South Africa continues, with all the bones being digitally scanned, the files released online. Her anthropology students are among those puzzling over the pieces. The MJC computer graphics department is producing 3-D printouts of the pieces of one hand for students to touch and try to assemble.

Getting a real fossil is a long and costly process, she said, “Now we can print our own from public sources.”

In the college’s newly opened Center for Advanced Technologies computer lab, professor Joel Hagen held out a tiny plastic bone printed that morning. “This is hot off the press,” he said with a chuckle.

This story was originally published September 20, 2015 at 6:06 PM with the headline "Modesto professor part of team picked to probe Rising Star find in South Africa."