Many people used to get extremely upset at the ill-formed notion that “man descended from the apes.” Such words were much more likely to start fights or “monkey trials” than the correct notion that all living animals, including man, ascended or evolved from a single-celled organism which lived in the primeval seas hundreds of millions of years ago. Men are mammals, of the order called Primates, and man’s living relatives are the great apes. Men didn’t “descend” from the apes or apes from men, and mankind must have had much closer relatives who have since become extinct.
Men stand erect. They also walk and run on their two feet. Apes are happiest in trees, swinging with their arms from branch to branch. Few branches of trees will hold the mighty gorilla, although he still manages to sleep in trees. Apes can’t stand really erect in our sense, and when they have to run on the ground, they use the knuckles of their hands as well as their feet.
A key group of fossil bones here are the South African australopithecines. These are called the Australopithecinae or “man-apes” or sometimes even “ape-men.” We do not know that they were directly ancestral to men but they can hardly have been so to apes. Presently I’ll describe them a bit more. The reason I mention them here is that while they had brains no larger than those of apes, their hipbones were enough like ours so that they must have stood erect. There is no good reason to think they couldn’t have walked as we do.