hemisphere. Even the marsupials in Australia produced a species (_Diprotodon_) as large as a rhinoceros with a skull three feet long. Any one of these would have been a meal for a whole pack of hunters, if they could kill it—as we may be sure they could. § 5. CONCLUSION From the addiction of some ancestral ape to animal food, and to the life of a hunter in order to obtain it, then, the special characteristics of Man seem to be natural consequences. The hypothesis from which everything follows is exceptionally simple and moderate. It is generally admitted that our ancestor was a large anthropoid—possibly more gregarious than others, possibly more apt to live upon the ground; but neither of these suppositions is requisite. He was adapted to his life, as the chimpanzee and gorilla are to theirs: in which, probably, they have gone on with little change for ages. But into his life a disturbing factor entered—the impulse to attack, hunt and eat animals, which extensively replaced his former peaceable, frugivorous habit. The cause of this change may have been a failure in the supply of his usual diet, or an “accidental variation” of appetite. Not a great number need have shared in the hunting impulse; it is enough that a few should have felt it, or even one. If advantageous and inheritable, it would spread through his descendants. It was advantageous (_a_) in enlarging their resources of nutrition, and (_b_) in enabling them to escape from the tropical forest. On the other hand, to those least fit for the new life it brought the disadvantages of more strenuous exertion and of competition with other carnivorous types. But with hands and superior intelligence, those that had the requisite character succeeded. There was rapid selection of those whose variations of structure, character, activity were most effective in dealing with game and with enemies; especially of those who combined and co-operated, and learned to direct co-operation by some rudimentary speech.