186 THE DESCENT OF MAN. [Part I 



bent, with the hands clasped round a branch or over its 

 own head. We should, however, bear in mind that the 

 attitude of an animal may perhaps be in part determined 

 by the direction of the hair ; and not the direction of the 

 hair by the attitude. If the above explanation is correct 

 in the case of the orang, the hair on our forearms offers a 

 curious record of our former state ; for no one supposes that 

 it is now of any use in throwing off the rain, nor in our pres- 

 ent 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 early progenitors ; for it is impossible 

 to study the figures given by Eschricht of the arrange- 

 ment of the hair on the human foetus (this being the same 

 as in the adult) and not agree with this excellent observer 

 that other and more complex causes have intervened. 

 The points of convergence seem to stand in some relation 

 to those points in . the embryo which are last closed in 

 during development. There appears, also, to exist some 

 relation between the arrangement of the hair on the limbs, 

 and the course of the medullary arteries. 8 



It must not be supposed that the resemblances be- 

 tween man and certain apes in the above and many other 

 points — such as in having a naked forehead, long tresses 

 on the head, etc. — are all necessarily the result of un- 

 broken inheritance from a common progenitor thus charac- 

 terized, or of subsequent reversion. Many of these resem- 

 blances are more probably due to analogous variation, 

 which follows, as I have elsewhere attempted to show, 9 



8 On the hair in Hylobates, see ' Nat. Hist, of Mammals,' by C. L. 

 Martin, 1841, p. 415. Also, Isid. Geoffroy on the American monkeys and 

 other kinds, 'Hist. Nat. Gen.' vol. ii. 1859, pp. 216, 243. Eschricht, ibid- 

 B. 46, 55, 61. Owen, 'Anat. of Vertebrates,' vol. iii. p. 619. Wallace, 

 'Contributions to the Theory of Natural Selection,' 1870, p. 344. 



9 ' Origin of Species,' 5th edit. 1869, p. 194. ' The Variation of Ani 

 tnals and Plants under Domestication,' voL ii. 1868, p. 348. 



