During this period, a changing climate forced our ancestors to move out of the forests and into more open territory. They had to adapt to new foods and new predators, which may have spurred the development of our distinctly larger brains. Animal fossils found near the jaw fragment suggest the individual lived in a savannah environment.
“It confirms this idea that our lineage, Homo, is a response to climate change,” says Brian Villmoare, a paleoanthropologist at the University of Nevada, Las Vegas. “If the climate had not changed at 3 million years ago, Australopithecus could very contentedly still be existing.”