Some new research has been released regarding Homo habilis and a new link to a primate common ancestor. H. habilis is the earliest known member of the Homo branch from which modern humans, H. sapiens, come. A reconstruction of a H. habilis jaw bone has yielded some surprising results as it is far more primitive looking than thought. The jaw was found about 50 years ago but the reconstruction is recent.
In another find researchers from Arizona State University working in Ethiopia have found a jaw bone that pushes back the beginnings of the Homo genus to about 2.8 mya. The fossil is a lower jaw and it predates previously known fossils of the Homo genus by about 400K years. The jaw was actually discovered in 2013 and reports on the jaw have just been released following extensive analysis.
The fossil is being called the Ledi-Geraru fossil. It provides some clues about changes in the jaw and teeth in the Homo genus only 200K years after the last known occurrence of Australopithecus afarensis (Lucy) whose fossil was found nearby. Analysis of the jaw has revealed advanced features such as slimmer molars and an evenly proportioned jaw shape along with symmetrical premolars which are all features that distinguish the Homo genus from the more ape-like Australopithecines. Fossil remains of the Homo genus older than 2mya are extremely rare.
Researchers say that the reconstructed H. habilis jaw provides a good link back to the Ledi fossil. Further, the Ledi fossil narrows the evolutionary gap between Australopithecus and the early Homo genus. They also say the Ledi fossil is a transitional fossil (missing link) between the two (H. habilis and Australopithecus).
Global climate change is believed by many researchers to have stimulated species appearances and extinctions including the emergence of the Homo genus (modern humans).