Hair of the Chest.

In the hair-streams on the chest of our chosen three, lemur, ape and man, there are also some remarkable contrasts in the course they take. Fig. 42 shows these in a vivid manner. Precisely as in the case of the hair on the backs of lemurs, apes and man, we find on the chest of those three types a normal direction on the two lower ancestors and an entirely novel arrangement in man; the former, therefore, will need no verbal descrip­tion.

Man, the ever bold explorer and innovator has initiated on his chest, as on his back, a fashion in hair unknown in any of the primates. He is, in respect of his hair on these two regions, sui generis. On the chest there is a critical area extending across the sternum at the level of the second rib from a whorl which is found on each side somewhat above the nipples. This is not less an ancient battle-field than the Border which separated England and Scotland, and it has been the site of its little conflicts, more especially north of the Border, corresponding to those of the wild days of Border warfare of which Scottish history is full.

Fig. 42.—Arrangement of hair on the chest of lemur—chimpanzee—man.

At this level of the chest two streams of hair are directly opposed to one another. That which covers the chest below the dividing line maintains in true old English style its conservative fashion and passes downwards as in the ape and lemur. The more independent or Scottish stream goes upwards on its way to the neck, the side streams passing somewhat outwards towards the side of the neck, the central upwards and inwards, converging gently on to the front of the neck. The arrows in the figure show this very clearly. On the front of the neck the stream pursues its upward way until it meets the downward flowing stream from the lower jaw, and the junction of these two streams lies over the level of the upper border of the larynx in front, winding gently outwards and upwards to the surface just below the lobes of the ears. The opposi­tion of the two streams in the neck is very familiar, as a piece of practical experience, to those who shave, for it affords a decided little resistance to the razor as it is drawn downwards, and many persons change the position of the razor in consequence of it, without troubling their heads with any scientific reason for the fact.

These are the facts of the distribu­tion of hair on man’s chest, but what is the interpreta­tion? I would remark here that in my former book[56] I gave what seemed to be then the best reason for it, but further reflec­tion on the matter has shown me that it was incorrect and inadequate. I refer to this and one or two other corrections of earlier views in a later chapter.