In 2015, scientists announced they had discovered 15 skeletons of an unusual new species of human cousins, clustered together deep in a remote chamber of the Rising Star cave system in South Africa. Homo naledi, as the species was named, was an enigma to researchers. Some of its features, like its long legs, small teeth and dexterous wrists, resembled modern humans; but its small brain size and curved fingers suggested it was more closely related to our ape-like Australopithecus ancestors.
This week we have one answer about the history of these fossils: how old they are. In a series of papers published in the journal eLife, a team led by Professor Lee Berger of The University of the Witwatersrand in Johannesburg, South Africa, announced that the Homo naledi fossils are between 335,000 and 236,000 years old. That means these primitive, long-lost cousins lived at the same time as Homo sapiens, the first time it has been shown that another species of hominin survived alongside the first humans in Africa.
Myra Laird, a postdoctoral scholar at the University of Chicago, worked on the project, studying the features of the Homo naledi skulls and comparing them to other fossils to determine whether a new set of specimens, found in second cave near the original site, were of the same species. She began the work as a graduate student at New York University, and continued after she moved to UChicago, where she also published a paper about the skull in the Journal of Human Evolution last fall.
One of the most memorable moments, Laird said, was putting together the face of Neo, one of the newly discovered skulls.
“Fossil hominins rarely preserve the face because the bones are quite fragile, so it was really exciting when my colleagues and I finally pieced together the bones of the face,” she said. “We all stood back and just stared for a couple of minutes. It was like fitting the final piece into a complicated puzzle.”