∞ generated and posted on 2015.12.27 ∞

Walking on two legs.

Bipedalism refers to an ability among especially tetrapods (reptiles and their descendants) to stand and then walk using particularly just their two hind limbs to effect locomotion as well as balance.

Bipedalisms is seen in multiple animal lineages including the theropods (which includes the birds) and the lineage including australopiths along with genus Homo. Indeed, it serves as a defining feature of most hominins.

Occasional bipedal walking is seen among an even greater variety of animals:

Animals that are habitually bipedal are known as bipeds.

Contrast bipedalism with quadrupedalism.

The following video attempts to animate Australopithicus with some discussion of evidence for its bipedalism.

The following video presents one hypothesis for why bipedalism may have evolved in our lineage as well as a nice graphic in the beginning illustrating ancestral bipedalism (though probably this is represented as being too upright).