Males of the extinct human species Paranthropus robustus were thought to be substantially larger than females — much like the size differences seen in modern-day primates such as gorillas, orangutans and baboons. But a new fossil discovery in South Africa instead suggests that P. robustus evolved rapidly during a turbulent period of local climate change about 2 million years ago, resulting in anatomical changes that previously were attributed to sex.
An international research team including anthropologists at Washington University in St. Louis reported their discovery from the fossil-rich Drimolen cave system northwest of Johannesburg in the journal Nature Ecology & Evolution on Nov. 9.
“This is the type of phenomenon that can be hard to document in the fossil record, especially with respect to early human evolution,” said David Strait, professor of biological anthropology in Arts & Sciences at Washington University.
The remarkably well-preserved fossil described in the paper was