The two amateur cavers had to feel their way along the South African cave’s winding passages, crawl on their stomachs through an opening less than 10 inches high, ascend a jagged wall, cross a narrow ledge dubbed the Dragon’s Back, and make a 400-foot descent, sideways, through a vertical crack before finally arriving at the prize — a 30-foot-long chamber probably between 2 million and 3 million years old.
American paleoanthropologist Lee Berger had asked the men to keep their eyes open for fossils, though the well-explored cave at the Cradle of Humankind World Heritage Site had given up most of its treasures decades ago.
What they found in September 2013 nearly took their breath away: fossil fragments of a relative of the human species, and a cache of bones and teeth buried in ancient clay that would eventually number more than 1,500 — the largest hominin fossil discovery of its kind in Africa.
After a month of excavation under some of the most difficult and dangerous of conditions, then two years of analysis by more than 50 international experts, Berger, a researcher in human evolution at the University of the Witwatersrand in Johannesburg, and the leaders of the expedition announced Thursday that those fossil fragments indeed do belong to a new species of human relative they are calling Homo naledi.
The announcement by the university, National Geographic and the South African Department of Science and Technology/National Research Foundation, was made in Johannesburg, about 25 miles northwest of the cave complex, called the Rising Star, where the fossils were found.
“Naledi” means “star” in Sesotho, a local South African language, and the chamber where the fossils were unearthed was called Dinaledi, or “many stars.”
The fossils were recovered in November 2013 and March 2014 by a team assembled by Berger and his colleagues through social media. The archaeologists thought the only way to mount a major excavation was to have a team of people slender enough to fit into the cave but also experienced enough to handle the hazardous work.
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The six who eventually were chosen were all women, including then-University of Iowa paleoanthropology doctoral candidate K. Lindsay Eaves. She since has married co-discoverer Rick Hunter and is now pursuing a Ph.D. at the University of Witwatersrand.
“I have had nearly two years to absorb the enormity of this fossil discovery for paleoanthropology but was overwhelmed today by the outpouring of emotion from the South African people, who have taken Homo naledi as a symbol of our common humanity,” she said Thursday via an email to The Gazette from South Africa.
“I feel both honored and privileged to have been a part of the international team responsible for bringing the naledi fossils to the surface and their story to light.”
The pieces belonged to at least 15 individuals of the same species — men, women, children and infants — and all of them appeared to have been deliberately placed there after death. The implication, as astonishing as the initial discovery, was it suggested the ritualized disposal of bodies.
H. naledi is an unusual combination of the primitive and the modern, the scientists said. Its brain was no larger than a baseball; its shoulders and torso primitive; its fingers long and curved, allowing H. naledi to climb and swing from the trees. At the same time, H. naledi’s wrist bones indicated it used tools. Its long legs and feet, nearly indistinguishable from those of modern man, allowed it not only to walk upright but also to travel for many miles at a time.
Gazette writer Alison Gowans contributed to this story.