Percentage of muscle distribution to upper and lower limbs in Pongo pygmaeus, Gorilla gorilla, P. paniscus, and H. sapiens.

The regional distribution of muscle in H. sapiens contrasts significantly with the regional distribution of muscle in P. paniscus and other apes. Of total muscle mass in H. sapiens, more than half acts on the lower limbs and only a fifth acts on the upper limbs (36, 37), whereas a third of P. paniscus muscle acts on the upper limbs (Fig. 1).