"Australopithecus afarensis" seems to have had the same conical rib-cage found in today's non-human great apes (like the chimpanzee and gorilla), which allows room for a large stomach below and indicates the longer intestine needed for digesting voluminous plant matter.Fully 60% of the blood supply of non-human apes is used in the digestion process, greatly impeding the development of brain function (which is limited thereby to using about 10% of the circulation).