'First human' discovered in Ethiopia
By Pallab Ghosh
Science correspondent, BBC News
The fossil's teeth are smaller than those of other human relatives
Scientists have unearthed the jawbone of what they claim is one of the very first humans.
The 2.8 million-year-old specimen is 400,000 years older than researchers thought that our kind first emerged.
The discovery in Ethiopia suggests climate change spurred the transition from tree dweller to upright walker.
