Two early humans found in Africa 10 years ago appear to represent a "missing link" with our ape-like ancestors, CNN reports. A new study broke ground this week by saying the two-million-year-old partial skeletons are from a new species called Australopithecus sediba that walked upright but spent time in trees—a transition between the ape-like genus Australopithecus and the genus Homo that apparently began using tools. Seems Australopithecus sediba had hands and feet that were good for both climbing trees and grasping tools. "This larger picture sheds light on the lifeways of A. sediba and also on a major transition in hominin evolution," says lead researcher Scott Williams of New York University.
In nine papers in PaleoAnthropology, leading anthropologists analyze various parts of the fossils and refute critics who either doubted the new species existed or said the skeletons were of two different species, per Phys.org. They also recall the fossils' incredible 2008 discovery by a nine-year-old who was walking his dog in South Africa when he tripped over a rock. "Imagine for a moment that Matthew stumbled over the rock and continued following his dog without noticing the fossil," they write. "If those events had occurred instead, our 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." The authors call it a reminder that "there is still so much to discover about our evolutionary past." (Here are the best science books of 2018.)