Ardipithecus ramidus ('Ardi') reshapes the human-ape ancestor

Date

c. 4.4 million years ago

Category

Science, technology & invention

Region

East Africa (Ethiopia)

Era

Prehistory

Significance

Fossils of Ardipithecus ramidus were excavated near Aramis in Ethiopia's Middle Awash by a team led by Tim White between 1992 and 1994, but the analysis of the partial skeleton nicknamed 'Ardi' was not published until 2009.

Dated by argon dating of enclosing volcanic ash to about 4.4 million years ago, Ardi is a small-brained female preserving much of the skull, pelvis, hands and feet. Her anatomy combined an opposable, grasping big toe and long arms suited to moving through trees with a pelvis modified for upright walking on the ground — a mosaic of arboreal and bipedal traits. Critically, Ardi lived in a wooded setting, challenging the long-held 'savanna hypothesis' that bipedalism arose as forests gave way to grassland. Her reduced canine teeth and overall body plan undercut the once-popular assumption that the last common ancestor of humans and chimpanzees resembled a modern chimp, suggesting instead that living apes are highly specialised rather than living fossils. Published as a landmark suite of papers in Science, Ardi profoundly reframed how researchers reconstruct the earliest stages of human evolution.

Related science, technology & invention events

• Omo Kibish fossils: oldest known Homo sapiens of East Africa
  c. 233,000 years ago
• The Herto crania (Homo sapiens idaltu)
  c. 160,000 years ago
• Australopithecus afarensis ('Lucy' and relatives)
  c. 3.9–2.9 million years ago
• Discovery of the Denisovans and archaic-modern interbreeding
  c. 100,000 – 40,000 years ago (interbreeding); identified 2010
• Domestication of maize from teosinte in Mesoamerica
  c. 7000 BCE (c. 9,000 years ago)
• Domestication of rice in the Yangtze River basin
  c. 8000–6000 BCE

Also relevant

• Homo erectus emerges and begins long-distance migration
  c. 1.9 million years ago
• Homo floresiensis, the 'Hobbit' of Flores
  c. 100,000 – 50,000 years ago
• Homo heidelbergensis: the Mauer jaw and a shared ancestor
  c. 600,000 years ago

Further reading

A Little History of Science

The wider story

A Little History of Science

William Bynum

Warm, jargon-free tour of discovery from Babylonian stargazers to the genome.

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