Can gorillas walk upright?

Gorillas are quadrupeds whose usual mode of locomotion is the so-called knuckle walk, which means they partially flex the fingers of their hands such that their knuckles bear their weight. The mountain gorillas of the Virunga Volcanoes spend 94% of their time moving about in this way. However, they occasionally stand and walk upright, particularly when they are displaying. When they do this, however, they keep their knees bent at all times and their upper body tilts forward, whereas a human’s upper body and legs form a vertical axis when walking.

When humans evolved from walking on four legs to walking on two, the human pelvis underwent major changes: the hip joints adapted and the two iliac wings became shorter and wider as the internal organs need to be supported when in an upright position. In contrast, the gorilla’s hip joints and pelvis are adapted to the gait of a quadruped. Apes can move on two legs only for a short time, because their anatomy is not designed for this.