Ardi, oldest known skeleton of a human ancestor

Internet, meet Ardi, the newest member of the human branch of the primate family tree.

Or rather, the oldest. Discovered in Ethiopia in 1994, Ardi is a 4.4 million-year-old partial skeleton of a female Ardipithecus ramidus.

The fossil puts to rest the notion, popular since Darwin's time, that a chimpanzee-like missing link -- resembling something between humans and today's apes -- would eventually be found at the root of the human family tree. Indeed, the new evidence suggests that the study of chimpanzee anatomy and behavior -- long used to infer the nature of the earliest human ancestors -- is largely irrelevant to understanding our beginnings.

Ardi instead shows an unexpected mix of advanced characteristics and of primitive traits seen in much older apes that were unlike chimps or gorillas. As such, the skeleton offers a window on what the last common ancestor of humans and living apes might have been like.

This is a major discovery; Science is devoting a special issue to the find with 11 detailed peer-review papers and general summaries. I expect we'll be hearing more about this in the coming weeks as all that science filters through the lay media. (thx, jeff)