In October, after 17 years of investigation, researchers reported detailed descriptions of the oldest hominid skeleton yet found. The fairly complete 4.4-million-year-old female Ardipithecus ramidus fossil — known as Ardi — was discovered in Ethiopia.
Analysis of the remains by Tim White at the University of California, Berkeley, and a large team of collaborators revealed that humans did not evolve from ancient chimpanzees, as has long been believed. Humans instead evolved along a separate lineage from the last common ancestor shared by early hominids and extinct apes.
Like modern humans, Ardi could walk upright and didn't use her arms for walking, as chimps do. However, she retained a primitive big toe that could have been used in ape-like tree grasping.
Years of field work uncovered Ardi's skull, teeth, arms, hands, pelvis, legs and feet (composite photograph pictured). The paper is accompanied by 10 companion articles.