Ardi, a 4.4-million-year-old skeleton, walked upright yet grasped branches with her toes
Found in Ethiopia's Afar desert and unveiled in 2009, the skeleton nicknamed Ardi belonged to a 50-kilogram female who lived more than a million years before Lucy. She had a small brain and an opposable big toe for climbing, and experts still argue whether she belongs on the human line at all.
Ardipithecus is an extinct genus from the Late Miocene and Early Pliocene of the Afar Depression in Ethiopia. Two species are described: A. ramidus, about 4.4 million years old, and the older A. kadabba, around 5.6 million years old and known only from teeth and scraps of bone. The names come mainly from the Afar language: ardi means ground or floor, ramid means root, and kadabba means basal family ancestor, joined to the Greek word for ape.
A team led by Tim White found the first ramidus fossils in 1992 and 1993 in the Middle Awash valley, seventeen fragments including skull, jaw, teeth and arm bones. First assigned to Australopithecus, the species got its own genus and was named in September 1994, the year more bones turned up. By then 45 per cent of a skeleton had been recovered. On October 1, 2009, researchers formally presented it: Ardi, from a site called Aramis, with most of the skull and teeth plus pelvis, hands and feet, found just 74 km from where Lucy was discovered in 1974.
Her anatomy is a mosaic. The brain measured 300 to 350 cubic centimetres, a little smaller than a chimpanzee's and roughly a fifth of ours. Unlike any hominin recognised before, she had a grasping big toe, yet her pelvis and limbs suggest she walked on two legs on the ground and went on all fours in the trees, though not for long distances. Her teeth point to a generalised diet of fruit and other foods, and males had small, blunt canines barely different from females', which some take as a sign of relatively peaceful male relationships in our earliest ancestors.
Her place in the family tree is disputed. Primatologist Esteban Sarmiento argued Ardipithecus shares no features exclusive to humans. Others point to hand and skull-base traits found only in the human lineage, and some analyses make Australopithecus a sister to ramidus, meaning the lineage lives on, in a sense, in us.
Source: Ardipithecus
