The discovery of a fossilized jawbone in Ethiopia has helped fill an important gap in the understanding of human evolution. The discovery was made in 2013 by an international team led by Arizona State University scientists. The team published two papers on their work this week for the online version of Science.
The fossil, designated as LD 350-1, is an important find because it's the earliest evidence for the genus homo in the human evolutionary line.
"Sedimentary basins in eastern Africa preserve a record of continental rifting and contain important fossil assemblages for interpreting hominin evolution," reads the abstract from one of the group's papers on their field work in Ethiopia.
"However, the record of hominin evolution [human evolution] between 3 and 2.5 million years ago (Ma) is poorly documented in surface outcrops, particularly in Afar, Ethiopia. Here we present the discovery of 2.84-2.58 Ma fossil and hominin-bearing sediments in the Ledi-Geraru research area that have produced the earliest record of the genus Homo."
The story of human evolution is being rewritten because the jawbone is roughly 400,000 years older than Homo habili, which had previously been the oldest known species in the Homo lineage.
ABC Australia reports that LD 350-1 sheds light on changes in jaws and teeth of the Homo species only 200,000 years after the passing of the Australopithecus genus. In fact, the primitiveness of the front of the jawbone suggests an Australopithecus origin, while the back jawbone and teeth point to the more recent Homo habilis.
University of Nevada's Dr. Brian Villmoare places the fossil between the two groups, and suggests that the jawbone's design is indicative of a new diet in human evolution.
"At three million years ago, you have a very ape-like creature with long arms, living in the forest, probably eating fruit," Villmoare said.
"And then at two million years ago you have Homo with the tools and large brain and more modern body plan with shorter arms. The big gap between those two is really interesting because something must have happened that led to the evolution of us."
Modern humans evolved in Africa around 200,000 years ago. Although the story of human evolution and the primate ancestors that came before modern humans is millions of years in the making, scientists believe that human evolution only spawned "modern" behavior around 50,000 years ago.
Going back earlier in the history of human evolution, the Inquisitr previously reported on the findings establishing a link between human hands and fish fins. Thanks to advancements in DNA sequencing, pioneering work in the field of genetics is helping to write new chapters in the tale of human evolution.
[Image via Science Daily/Brian Villmoare]