It's just a small piece of a jawbone with five teeth, but its discovery in Ethiopia is changing the timeline of human origins. Researchers say the bone is from an individual who lived 2.8 million years ago and belonged to the genus Homo, the lineage from which modern humans emerged. In fact, this is the earliest known member of the group ever found—by about 400,000 years, reports AP. A student from Arizona State University found the fossil in 2013 in the same general area where one of the most famous fossils in history was discovered, that of "Lucy," an ape-like ancestor that lived about 3 million years ago. The newly discovered fossil might be the link between Lucy, or Australopithecus afarensis, and the first primitive humans, reports the BBC.
"That's what we are arguing," says Brian Villmoare of the University of Nevada in Las Vegas. "By finding this jaw bone we’ve figured out where that trajectory started. This is the first Homo. It marks in all likelihood a major adaptive transition.” It's not clear yet whether the fossil belongs to a species of Homo previously known, such as Homo habilis, or is an entirely new one, reports the Guardian. An expert from George Washington University not involved with the find says it seems safe to conclude that the creature was either at the start of the Homo line or "within shouting distance." (Elsewhere, archaeologists found a long-lost city under the Honduran jungle.)