OCR Text |
Show 284 SEXUAL SELECTION : 1\:IA:Ml\!ALS. PaRT II. But with most kinds of monkevs the various tufts of hair about the face and head are" alike in both sexes. The males of various members of the Ox family (Bovidoo), and of certain antelopes, are furnished with a dewlap, or gl'eat fold of skin on the neck, which i~ much less developed in the female. Now, what must we conclude with respect to such sexual differences as these? No one will pretend that the beards of certain male-goats, or the dewlap of the bull, or the crests of hair along the backs of certain male antelopes, are of any direct or ordinary use to them. It is possible that the immense bea1~d of tho male Pither.in, and the large beard of the male Orang, may protect their throats when fighting; for the keepers in the Zoological Gardens inform me that many monkeys attack each other by the throat: but it is not probable that the board has been developed for a distinct purpose from that which the whiskers, moustache, and other tufts of hair on the face serve; and no one will suppose that these are useful as a protection. Must we attribute to mere purposeless variability in the male all these appendages of hair or skin? It cannot be denied that this is possible ; for with many domesticated CJUadrupeds, certain characters, apparently not derived through reversion from any wild parent-form, have appeared in, and are confined to, the males, or are more lnrgely developed in them than in the females,-for instance the hump in the male zebu-cattle of India, the tail in fat-tailed rams, the arched outline of the forehead in tl1e males of several breeds of sheep, the mane in the rnm of an African breed, and, lastly, the mane lono· • ' b hnu·s on the hinder legs, and the dewlap in the male alone of the Be1·bura goat.18 The mane which occurs in Ia Sec the chApters on these several animvls in vol. i. of my' Variu~ ion of Animals under Domcsticution;' also vol. ii. p. n i abo chap. XX. ( ; JIAI'. XVIII. DEVELOPMENT OF liAlU. 285 the rams alone of the above-mentioned. African breed of :-;hoop, is a ·true secondary sexual character, for it is not <levcloped, as I hear from Mr. vVinwood Reade if the animal Le castrated. Although we ought to 'be extremely cautious, as shewn in my 'rork on 'variation under J?omest.ication,' in concluding that any character, ·0\ren w1th an.Imals kept by semi-civilised people, has not been suLJected to selection by man, and thus auO'mentecl; yet in the cases just .specified this is i~probable~ more especially as the characters are confined to th~ males, or are more strongly developed in them than m. the femal~s. If it were positively known that the Afncan ram w1th a mane was descended from the same p1·imitive stock with the other breeds of sheep, or tho Berbura male-goat with his mane dewlap &c f :·om t he same stock with other goats ; ' and if s' elcc.-, twn has not been 8.pplied to these characters, then they mus~ ~e d~e to simple variability, together with sexually-limited mheritance. In this case it would appear reasonable to extend t.he ~arne ~iew to the many analogous characters occurrmg m ammals under a state of nature. Neverthel~ ss I c.annot persuade myself that this view is applicable m many cases, as in that of the extraordinary development of hair on the throat and fore-legs of the male Ammotragus, or of the immense beard of the male Pithecia. 'With those antelopes in which the ~ale when a~ult is morE1 strongly-coloured than the ie.male, and w1th those monkeys in which this is likew! se the case, and in which the hair on the face is of a different colour from that on the rest of the head, beino· ~rranged in the most diversified and elegant manne~ 1t seems probable that the crests and tufts of hair have QD the practice of selection by semi-civilised people. For the Berburu goJt, see Dr. Gray, 'Cablogue,' ibid. p. 15i. |