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In order to gain a clear conception of the zoological relations of man, let us recapitulate the life-history of the individual man from the beginning
We shall find the future human being a mere nucleated cell, a little speck of albuminous jelly already described (in Chap. VI.) as the mammalian egg. So closely do the form, the size, and the structure of this little cell remind us of the amoeba-cell, that Haeckel's inference is most natural :
“ The ancestors of the higher animals must be regarded as one-celled beings, similar to the amabæ which at the present day occur in our rivers, pools, and lakes. The incontrovertible fact, that each human individual develops from an egg, which, in common with those of all animals, is a simple cell, most clearly proves that the most remote ancestors of man were primordial 1 animals of this sort, of a form equivalent to a simple cell. When, therefore, the theory of the animal descent of man is condemned as a “horrible, shocking, and immoral' doctrine, the unalterable fact, which can be proved at any moment under the microscope, that the human egg is a simple cell which is in no way different to those of other mammals, must equally be pronounced horrible, shocking, and immoral.'"
Nor is this resemblance to the lower animals confined to the egg-stage of the human being ;
I Belonging to one of the first geological perioils.
for, after the development of the ovum is fairly under way, there are some weeks in the life of the human embryo during which no more could be decided, from the closest study of it, than that it was (like the embryo described by Von Baer, as quoted in Chap. VI.) that of some animal with a backbone. At a later period of embryonic life, we shall find that the human embryo has taken on a form peculiar to mam. mals, and that this form soon becomes as strikingly like the embryo of an ape as either is now different from that of any other mammal.
The human infant, also, has some very apelike characters; such as the narrow hips, the soles of the feet brought toward each other by the incurving thighs, the protuberant abdomen, the disproportionate length of the arms, the shortness of the hair on the head, and the general distribution of hair over the body, and the lack of a bridge to the nose. On the other hand, the young ape has a far more human or less brutish look tian the adult, from the fact that the huge projecting jaws and teeth, such as appear in the adult gorilla for example, are only attained at a rather mature age. So it is, too, with the great, bony ridges on the skull of this ape. Now, the tendency of such embryonic and infantile resemblances as have jut
been alluded to — special resemblances between man and apes, since they are shared with no other mammals - is to lead us to infer, that, if we are related to any of the lower animals, we are most closely related to the apes. And, if they and we are descended from a common ancestry, we should expect to find the likeness between the human being and the ape closest in the embryonic stage of existence, and growing less towards maturity, as is really the case. But how closely similar is the human body and the body of one of the higher apes? How great an external resemblance there is, the preceding figure of one of the most manlike apes will show better than words. How great is the similarity in structure, let Professor Huxley answer.
After a full account of the characteristics and habits of the gorilla, chimpanzee, orang, and gibbons, followed by a minute anatomical comparison of these animals with each other, with lower members of the order, and with man, he says, –
“ Whatever part of the animal fabric, whatever series of muscles, whatever viscera,2 might be selected for comparison, the result would be the same,
the lower apes and the gorilla would differ more than the gorilla and the
1 Contents of the great cavities of the body. 2 Man's place in Nature, p. 101.
But it is often urged that man is the only animal that has two hands and two feet, and that in this respect there is a vast gap between the highest ape and man. To this Professor Huxley answers, that the foot of man differs from his hand mainly :
1. By the different arrangement of the anklebones from the wrist-bones.
2. By the possession of two short muscles in the foot, - one in the under, and the other in the upper part of it, — which serve respectively to bend and to straighten the toes.
3. By the possession of a muscle (the peronæus longus) which is attached to the outer leg-bone, and whose cord or tendon passes over the outer part of the ankle, and then obliquely across the foot, to its attachment at the base of the great toe. Neither the two short muscles found in the foot, nor the peronæus longus, nor any thing like either of them, is to be found in the human hand and arm.1 Now, "Every monkey and lemur exhibits the characteristic arrangement of tarsal (ankle] bones, possesses a short flexor [bending] and extensor [straightening) muscle, and a peroncus longus.” 2
The old epithet four-handed, as applied to
1 Huxley, Man's Place in Nature, p. 107.
2 Ibid., p. 112.