The Frugivora.—The orang and the gorilla are perhaps the best examples of this class of animals. Some bats and kangaroos may be included in it also. Animals belonging to this class have thirty-two teeth—sixteen in each jaw; four incisors or cutting teeth; two pointed teeth, known as cuspids, four small molars, known as bicuspids, and six molars. The eye-teeth project somewhat beyond the others and fit into a blank space in the lower row, the other teeth articulating uniformly. I have referred to the uses of this large eye-tooth elsewhere (p. 29).
The Teeth of Man.—Now when we come to consider the teeth of man, we are at once struck by the fact that they correspond, in almost every particular, with the teeth of the gorilla and other frugivorous animals; and the fact they do not at all resemble or correspond to the teeth of any other animal! To the teeth of the herbivora, the carnivora, the omnivora, etc., they bear but the slightest resemblance, while they agree in almost every respect with the teeth of frugivorous animals. If we compare the teeth of man with those of the orang, the gorilla, or other frugivorous animal, we find that the number, the arrangement, the structure, the nature, and the size of the teeth are almost identical; while they bear but the smallest resemblances to the teeth of any other animal or genera. The complete absence of intervening spaces between the human teeth characterises man as the highest and purest example of the frugivorous animal. Man possesses no long, canine tooth, capable of catching and holding a captured prey; he possesses no tusks, like the omnivorous animals, and in every other way bears no resemblance whatever to any other animal—while his teeth do bear the very greatest and most detailed resemblance to the teeth of the apes and frugivorous animals generally. Bearing all these facts in mind, then, we surely can have no hesitation in classifying man as a frugivorous animal—so far as his teeth are concerned. Considered from that point of view, man must be classed with the pure frugivora.
Not only in the number and structure of the teeth, but also in the manner of masticating the food—in the movements of the teeth and jaws themselves—there is a distinct resemblance between man and the apes and other frugivora, and a radical distinction between him and all other animals. In herbivorous animals the jaws have three distinct motions—a vertical, or up-and-down motion; lateral or sidewise; and forward and backward. These movements are frequent and free, the result being that food eaten by these animals undergoes a thorough grinding process well suited to the nature of their food. In the carnivorous animals, on the other hand, the movements of the jaws are in one direction only—they open and shut “like a pair of scissors,” as one author said, and are well adapted for tearing and biting off food that is to be swallowed more or less en masse, to be acted upon by the powerful gastric juices of the stomach. No such limited action is the case with man. With him also the jaws can move in three directions—as in the case of the herbivora—but the extent of such motion is much more limited. In other words, the jaws of man are adapted to a diet necessitating more or less grinding, and he may be classed with the herbivora on that account. Whatever might be said, however, by way of associating man with the herbivora, he is certainly as distinct as possible from the carnivora, and resembles other animals far more than he resembles them. He is certainly not carnivorous, whatever else he may be!
Having thus passed in review the evidence presented by the teeth for the naturally frugivorous nature of man, we must now turn and examine the evidence afforded by the other organs of the body; and see how far comparative anatomy affords proof of the nature of man’s diet—as derived from a study of the other portions of his bodily frame. I shall review these in turn. First let us consider the extremities.
The Extremities.—According to Huxley, there are three great divisions in the animal kingdom, as regards the extremities—viz. those which possess hoofs, those possessing claws, and those possessing hands. To the first division belong the herbivora and the omnivora. Almost all animals possessing claws are carnivorous, while animals possessing hands are almost invariably frugivorous. To this rule there are very few exceptions. Since man certainly belongs to the class possessed of hands, he is certainly frugivorous by nature. The reason for this becomes apparent when we stop to consider the habits of the various animals. The herbivora have no need for hands; they have merely to walk about the grassy plains, and partake of what nature has offered to them in abundance. The carnivorous animal, on the other hand, takes his food by violence—suddenly springing upon some defenceless and unresisting animal, and tearing it to pieces with its sharp teeth and claws. For this reason they are developed to the size and extent we see—capable of inflicting such terrible injuries. And here I would again call attention to what I said before—as to the carnivorous traits and characteristics of the cat as compared with those of the dog. The teeth and claws are far more developed in the former than in the latter. In man, of course, his teeth and claws are entirely unfitted for any such office. The soft, yielding nails are absolutely unlike the long, sharp claws of the carnivora: nothing could be more dissimilar. But if we compare the hands and extremities of man with those of other frugivorous animals, there is a very close similarity between them. The reason for this is that man (like the apes) can and should go out into the open fields and forests and pick his food off the trees. The human hand is eminently adapted to this end and for this purpose; but is quite unadapted for any such purposes as the claws of the carnivora are adapted for. I may remark here, incidentally, that all carnivorous animals drink by lapping up the water or other liquid with their tongues; while man, and all vegetarian animals, drink by suction—by drawing up the fluid directly into the mouth. This is a very distinguishing characteristic, to which there are few if any exceptions. Needless to say, since man drinks by suction, he is eminently a vegetarian animal, and is quite distinct from the carnivora in this respect, as in all others.
The Alimentary Canal.—“One of the most interesting comparisons,” says Dr Kellogg,[5] “which has been made by comparative anatomists is the length of the alimentary canal. This is very short in the carnivora, and long in the herbivora. When compared to the length of the body of the different classes of animals, the proportion is found to be as follows:—In the carnivora, the alimentary canal is three times the length of the body; in the herbivora, as the sheep, thirty times the length of the body; in the monkey, twelve times; in the omnivora ten times; in man, as in the frugivora, twelve times. Here, as before, we see that anatomy places man strictly in the frugivorous class. Some writers have made the amusing blunder of making the proportionate length of the alimentary canal in man 1 to 6, instead of 1 to 12, by doubling the height through measuring him while standing erect. This measurement is evidently wrong, for it includes the length of the lower extremities, or hind legs, whereas in other animals the measurement is made from the tip of the nose to the end of the backbone. In omnivorous animals, the alimentary canal is shorter than in the apes and in man, thus affiliating this class more nearly with the carnivora than with the herbivora.
“A curious fact had recently been observed by Kuttner, as related by him in an article published in Virchow’s Archives. This author has made extensive anatomical researches respecting the lengths of the small intestine in different classes of persons. He finds that in the vegetarian peasants of Russia, the small intestine measures from twenty to twenty-seven feet in length, while among Germans, who use meat in various forms quite freely, the length of the small intestine varies between seventeen and nineteen feet. The author attributes the difference in these two classes of persons to the difference in diet. Of course differences of this sort must be the influence of the diet exerted through many generations. This observation would seem to suggest that the special anatomical characteristic of the carnivorous class of animals is due to the modifying influence of their diet, acting through thousands of years. If the length of the intestine in man may be shortened by the use of flesh, with other foods, for a few hundred years, more extensive modifications may easily result from the longer experience of animals that subsist upon an exclusively carnivorous diet.”[6]