( Originally Published 1936 )
THE Primates include Man, the Apes and Mon-keys, and the Lemurs.
Man naturally heads the list of mammals, standing at the top in the line of evolution, but his general bodily structure resembles the highest apes so closely that he is separated by zoologists from other forms of the order simply as a " family," with a single genus and species: the Hominidae (Homo sapiens). With the exception of the elephant, man has the largest brain of any of the mammals, and he is the only one of the higher animals that stands completely erect in walking.
In the early history of the world, man was regarded as being a separate creature from the rest of the animal kingdom, but scientists of a later day have decided that as an animal he in no wise differs from them except in the degree of his development; that in all his characters—in skeleton, general structure, blood, and so on—he is essentially a mammal. Man stands with his feet firmly planted on the ground, and, without the assistance of his arms as a means of support, is able to maintain the upright position; whereas, the higher apes, which most nearly approach him in this particular, are able to stand erect for but a limited time, and then only by raising the arms over the head, or by grasping the branches of trees. Man can, on the other hand, walk with some ease upon all-fours, and we often see how young children assume this position in creeping about. When in this attitude the resemblance to the four-handed animals is very marked, and we are able to recognise the fact that in animal form he is separated from them by no wide gap.
For many years scientists have been seeking for fossil remains of man which will connect him more closely with the creatures around him, and in different parts of the world a few such remains have been found. These bones seem to indicate, much as we might expect, a somewhat more monkey-like character than the human being at present exhibits: the jaws are larger and heavier, the forehead more re-treating, and altogether there is a closer resemblance to such types as the gorilla, chimpanzee, and orang. However, interesting as these discoveries are, they are still incomplete, and more important material must be found before the links connecting man with his remote ancestors are fully determined.
It is not proposed to include in this volume a study of the different races of man.
QUADRUMANA (Apes, Monkeys and Lemurs)
All Quadrumana, or four-handed, animals, including the apes, monkeys, gibbons, and lemurs, are so called because the large toe is set so as to be opposable to the other four, while, in most cases, the thumb in the fore limbs has the same character. As a rule they live in trees, are herbivorous in their diet, and larger apes are able to walk partially erect by balancing with their arms or by grasping the branches over their heads. Although so like man in their general physical structure, they do not, of course, approach him as nearly in mental capacity; and while such monkeys as the chimpanzees and orangs can do many things after the manner of a human being, it is more their man-like appearance that makes them seem intelligent than any real ability they possess. On the contrary, monkeys, with a few exceptions, are much less intelligent than dogs, elephants, or seals.
In the apes and monkeys the thumb is short compared to man's, and all the fingers and toes are provided with flat nails, and not claws, except in the marmosets. They are divided into two main groups.
This group contains the Apes and Monkeys of the Old World. In these, the thumb is always opposable (except in the few cases when it is lacking), the nostrils are placed close together, and the tail, if present, is not prehensile—that is, adapted for grasping, as a hand.