~3.2 million years agoReputable source · 2 sourcesWell documented
Walking Upright: Lucy and Australopithecus
On the timeline · around ~3.2 million years ago · Cenozoic
What happened
Australopithecus afarensis — including the famous 3.2-million-year-old partial skeleton 'Lucy,' found in Ethiopia — walked upright on two legs, while its curved toes and long arms show it could still climb trees.
Why it matters
Habitual upright walking (bipedalism) is one of the defining traits of the human lineage, freeing the hands and reshaping the body long before the brain enlarged.
Sources
- Smithsonian Human Origins Program. Australopithecus afarensis · Reputable source
- Smithsonian Human Origins Program. Walking Upright · Reputable source