how old are human beings?
Image caption 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.
So this new discovery pushes the human line back by 400,000 years or so, very close to its likely (pre-human) ancestor. Its mix of primitive and advanced features makes the Ledi jaw a good transitional form between (Lucy) and later humans..