A definite habit of the human infant, that of "crying"--the peculiar spasmodic howling of very young children--seems to be unknown in any of the apes. I do not know what ingenious reason may have been assigned for this difference. Apes laugh under the same circumstances as do men, but with less production of sound than is the case with man and the hyena. Man was, far back in his monkey-days, a social and companion-loving animal, and the fact that his laughing and his weeping are accompanied by noise is due to the desire for attention and sympathy from his friends. A great difference between man and apes is the greater power of expression of various feelings or emotions by the face, and also the greater variety and significance in man of the gestures both of the upper and the lower limbs. These again are methods of seeking for and gaining sympathy and co-operation. Though not all men and not all races in an equal degree have mobility and constantly varying expression in the face, yet it is the fact that the man-like apes which have been studied in life (the chimpanzee and orang) have even less variety and range of expression than the most unintelligent savages. Man seems to have developed in an ever-increasing degree the habit of watching and interpreting the face and of giving by it expression to his emotions and states of mind, thus establishing a ready means of producing common feeling and interest in a group of associated individuals. This seems to have led to a special appreciation of the features of the face, and so to the exercise of sexual selection, resulting in what we call "a standard of beauty" in regard to both shape and expression. It is quite possible that the reduction of the threatening canine teeth and projecting jaw may have been furthered by sexual selection when once a bite had become less effective than a blow with a sharp flint, and when persuasive sounds and gestures gained more adherents than the display of tusks by a snarl.
What I have written in this and the preceding chapters, on the differences and likenesses between apes and man and the probable steps of the transition from ape to man, may assist the reader to form a judgment as to the importance of such remains of extinct races of men as the skeleton of the Sainte Chapelle, the Heidelberg jaw, and the Piltdown jaw and cranium lately dug up in Sussex, in helping us to further knowledge of those steps. It should be definitely noted that we have not yet found any extinct animals, definitely to be classed as apes, which come nearer to man than the chimpanzee and gorilla, although we are led to infer that such creatures existed, and that their fossil remains will probably some day be discovered. On the other hand, we have in the jaw and skull recently discovered in the gravel of Piltdown, in Sussex, evidence of a man-like creature which was in most important features more ape-like than any fossil man yet discovered.