Laggards trying to catch up

摘要

Arecent issue of Science, the weekly journal of the American Association for the Advancement of Science, was devoted to research into "Ardi" or Ardipithe-cus ramidus, a 4.4m-year-old hominid species whose discovery deepens the understanding of human evolution. These latest studies suggest, among other things, that rather than descending from a closely related species such as the chimpanzee, the hominid branch parted earlier than previously thought from the common ancestral tree.