All must admit the probability, in a large tribe of animals with grasping power in their hands, and in the habit of using missiles occasionally, of one or more species coming to use them habitually. All the anthropoid apes are certainly intelligent enough to do this, if it should prove advantageous to them. Its principal advantage, however, would seem to be to a species that became largely carnivorous and needed to capture running or flying prey.
The habit of using implements is one of supreme importance in animal evolution. To it we owe man as he exists to-day. While animals confined themselves to their natural weapons of teeth and claws, their development must have remained a very slow one and been confined within narrow limits. When they once began to add to their natural powers those of surrounding nature, by the use of artificial weapons, the first step in a new and illimitable range of evolution was taken. From that day to this, man has been occupied in unfolding this method, and has advanced enormously beyond his primal state. A crude and simple use of weapons gave him, in time, supremacy over all the lower animals. An advanced use of weapons and tools has given him, in a measure, supremacy over nature herself, and raised him to a stage almost infinitely beyond that of the animal which trusts solely to teeth and claws.
So far as we know, only one of the innumerable species of animals attained this development; unless, indeed, the various races of men had more than one ape ancestor. For the appearance of man there became necessary, first, the development of an order of animals with power of grasp in their hands; and, second, the development of one or more biped species, with hands freed from duty as walking organs and capable of use in other directions. A third necessity was very probably the exchange of the frugivorous for the carnivorous habit, which would act as a predisposing agency in inducing the animal to desert the tree for the ground, and to employ weapons in the chase. The final result of all this would be an erect, walking, and running animal, with arms and hands quite free from their old duty, except during an occasional return to the tree, and with the necessary straightening of joints and development of supporting muscles.
What has been advanced above is, no doubt, largely a series of assumptions and conjectures, few of which are sustained by known facts. But as the matter stands, no other method of dealing with it can be adopted, since the facts in the case have in great part vanished. What we know positively is that man exists, and that in physical structure he is very closely related to the anthropoid apes. What we have excellent reason to feel assured of is that man has descended from the lower animals, and in all probability from an ape-like ancestor. We know that one or more species of anthropoid apes have become extinct, and can reasonably conjecture that one ancient species became modified into the form of man. We know that human remains have been found that, to some small extent, fill the gap between man and the ape. Correlative evidence exists in the variations in length of limb in the existing anthropoids, their efforts to walk upright, their varied degree of dependence upon the arms for locomotion, and the occasional use of missiles by these and lower forms. To these may be added the carnivorous tastes shown by many members of the ape family, with the indication that more decided carnivorous habits might readily be assumed.
Taking the stand that such a partly carnivorous anthropoid ape, biped in structure, appeared and made the ground its usual place of residence, we find ourselves on the direct trail of man. Long ago as this may have been, and far and difficult as was the journey to be made, the way was thenceforth straight and well-defined. Such an animal, living largely on animal food, and using weapons superior to its natural ones in the capture of prey, was essentially a man, however low may still have been its level of intelligence. Its feet were firmly fixed upon the upward track, and only time and stress of circumstance were needed to carry it upward to the high level of civilized man.
We may, indeed, go further than this. We are in a measure justified in saying what this man-ape was like, this creature which had left its early home in the trees and began to walk upright upon the earth, pursuing the larger animals and capturing them for food. It was probably much smaller than existing man, little if any more than four feet in height and not more than half the weight of man. Its body was covered, though not profusely, with hair, the hair of the head being woolly or frizzly in texture, and the face provided with a beard. The complexion was not jet black, like the typical negro, but of a dull brown hue, the hair being somewhat similar in color. The arms were lank and rather long, the back much curved, the chest flat and narrow, the abdomen protruding, the legs rather short and bowed, the walk a waddling motion, somewhat like that of the gibbon. It had small, deep-set eyes, greatly protruding mouth with gaping lips, huge ears, and in general a very ape-like aspect. Our warrant for this description of man's ancestor must be left for a later portion of our work. We shall only say here that it is based on known fact, not on fancy.