CHA.P. VI. Affinities and Genealogy. XJ' 



length in some species of Semnopitheciis ;' and in the Bonr.et 

 monkey (Jlaca^us radiatus) it radiates from a point on the crown, 

 with a parting down the middle. It is commonly said that the 

 forehead gives to man his noble and intellectual appearance ; but 

 the thick hair on the head of the Bonnet monkey terminates 

 downwards abmptly, and is succeeded by hair so short and fine 

 that at a little distance the forehead, with tbe exception of the 

 eyebrows, appears quite naked. It has been erroneously asserted 

 that eyebrows are not present in any monkey. In the species 

 just named the degree of nakedness of the forehead differs in 

 different individuals ; and Eschricht states ' that in our children 

 the limit between the hairy scalp and the naked forehead is 

 sometimes not well defined; so that here we seem to have a 

 trifling case of reversion to a progenitor, in whom the forehead 

 had not as yet become quite naked. 



It is well known that the hair on our arms tends to converge 

 from above and below to a point at the elbow. This curious 

 arrangement, so unlike that in most of the lower mammals, is 

 common to the gorilla, chimpanzee, orang, some species of 

 Hylobates, and even to some few American monkeys. But in 

 Uylobates ayilis the hair on the fore-arm is directed downwards 

 or towards the wrist in the ordinary manner ; and in H. lar it is 

 nearly erect, with only a very slight forward inclination ; so that 

 in this latter species it is in a transitional state. It can hardly 

 be doubted that with most mammals the thickness of the hair on 

 the back and its direction, is adapted to throw off the rain ; even 

 the transverse hairs on the fore- legs of a dog may serve for this 

 end when ho is coiled up asleep. Mr. Wallace, who has carefully 

 studied the habits of the orang, remarks that the convergence of 

 the hair towards the elbow on the arms of the orang may be 

 explained as serving to throw off the rain, for this animal during 

 rainy weather sits with its arms bent, and with the hands clasped 

 round a branch or over its head. According to Livingstone, the 

 gorilla also " sits in pelting rain with his hands over his head.'" 

 If the above explanation is correct, as seems probable, the direc- 

 tion of the hair on our own arms offers a ciuious record of our 

 former state ; for no one supposes that it is now of any use in 

 throwing off the rain ; nor, in our present erect condition, is it 

 properly directed for this purpose. 



It would, however, be rash to trust too much to the principle 

 of adaptation in regard to the direction of the hair in man or his 



» Isid. Geoefrcy, ' Hist. Nat. Gen.' Anat. und Phys.' 1837, s. 51. 

 torn. ii. 1859, p. 217. ' Quoted by Readc, ' The Afriras 



' ' ijfbei- die Richtung der Sketch book,' vol. i., 1873, p. 15!i, 

 Ha-'ire,' &c., Miiller's 'Archiv t'iir 



