Prior to Selam’s discovery, researchers knew very little about early human growth patterns as the early human fossil record consists of few children.
Because Selam’s baby teeth erupted in a pattern similar to a three-year-old chimpanzee’s, researchers now know children shared a chimpanzee’s fast growth rate.
However, they probably weren't hunting, Mc Pherron says; it is more likely that they were scavenging predator kills.
Still, the search for large-animal meat is an important step in human development.
This site is not far from the spot where the same research team, led by palaeoanthropologist Zeresenay Alemseged of the California Academy of Science, San Francisco, had previously discovered a 3.3-million-year-old juvenile .
"We've put this important, fundamental behaviour back into Lucy's time," says Mc Pherron, who is lead author of the new study. Previously, the earliest known date for tool usage was about 2.5 million years ago — right about the time that humanity's own genus, , was first emerging. "We're pushing much deeper into our evolutionary past," Mc Pherron says.
It's an important find, says David Braun, a Palaeolithic archaeologist at the University of Cape Town in South Africa, because our closest living relatives don't engage in such behaviours.
But her brain size indicates that a human growth rate was evolving.
CT-scans of her skull show small canine teeth forming in the skull, telling us she was female.