Scientists have unearthed the jawboneThe 2.8 million-year-old specimen is 400,000 years older than researchers
of what they claim is one of the very first humans.
thought that our kind first emerged.
The discovery in Ethiopia suggests climate change spurred the transition from
tree dweller to upright walker.
The head of the research team told BBC News that the find gives the first
insight into "the most important transitions in human evolution"...