When we first walked YouTube Video Notecards

Australopithecus afarensis

An early human ancestor which walked upright, dated to about 3.6 million years ago.

Bipedalism

The ability to walk on two legs, a key feature distinguishing humans from other primates.

Laetoli

A site in Tanzania where fossilized footprints of early human ancestors were discovered.

Ardipithecus ramidus

An ancient human ancestor known for having both climbing and bipedal traits, dated to about 4.4 million years ago.

Savannah hypothesis

The theory that changes in climate led early humans to adapt to bipedalism for more efficient movement on land.

Hominin

Any species that is more closely related to humans than to chimpanzees, including modern humans and extinct relatives.

Ardi

A partial female skeleton of Ardipithecus ramidus, nicknamed for its surprising blend of climbing and walking features.

Orrorin tugenensis

An early bipedal species that lived around 6 million years ago, known for its unique thigh bone shape.

Sahelanthropus tchadensis

Considered one of the oldest known potential bipeds, dated to around 7 million years ago based on its skull features.

Bowl-shaped pelvis

A pelvic adaptation in humans that allows for efficient upright walking.

Footprints

Trace evidence left in volcanic ash by ancient bipedal ancestors that have provided significant insights into human evolution.