Specimens discovered in South Africa 10 years ago represent the long-sought mysterious missing link in our knowledge of human evolution, scientists have concluded in a new research study.
The partly fossilized 2 million-year-old bones of an adult female and a juvenile male were found in 2008 in a cavern in Malapa near Johannesburg.
Researchers discovered that the Australopithecus sediba species is closely related to the Homo genus, and fills a key gap in the chain of human evolution between early humans and our more ape-like ancestors. The fossils are distinctive yet similar to species along the same timeline, according to researchers.
Scientists believe Australopithecus sediba was the bridge between the ape-like Australopithecus africanus (represented by the 3-million-year-old skeletal finds in Africa dubbed Lucy) and remnants of Homo habilis, which used tools between 1.5 and 2.1 million years ago.
All three species “spent significant time climbing in trees, perhaps for foraging and protection from predators,” according to the study in the journal PaleoAnthropology.
Australopithecus sediba’s hands have grasping capabilities more advanced than those of Homo habilis, which suggests that the species may also have used tools.
“This larger picture sheds light on the lifeways of Au. sediba and also on a major transition in hominin evolution,” wrote lead researcher Scott Williams of New York University.
The discovery has been the subject of a contentious debate. Some scientists believed they did not represent a new species, while others thought they may have represented two new species.
The remains of Australopithecus sediba were found by a 9-year-old boy who stopped to look at a rock he had tripped over while walking his dog.
“Imagine for a moment that Matthew stumbled over the rock and continued following his dog without noticing the fossil,” the scientists wrote in their study. “If those events had occurred instead, out science would not know about Au. sediba, but those fossils would still be there, still encased in calcified clastic sediments, still waiting to be discovered.”