366 THE BIOLOGY OF BIRDS 



§ 3. Originative Factors 



The general evolution idea is borne out by the occurrence 

 of variations in birds, both in a wild state and under domesti- 

 cation. There are over two hundred well-marked breeds of 

 domestic pigeons, and some ornithologists say that there are 

 at least ten of them which would be ranked as distinct genera 

 if they occurred wild. Yet there is very strong evidence 

 that all are scions of the blue rock-dove, Columha livia, 

 which still frequents shore-cliffs in several parts of Britain. 

 We may go further and say that domestic pigeons evolved 

 under man's superintendence from the particular variety 

 of Columha livia which has two dark bars on its wing. 



In the same way there is very strong evidence that all 

 the breeds of poultry — Hamburghs and Dorkings, Bantams 

 and Silkies, and all the rest of them, are descended from the 

 jungle-fowl, Callus hankiva, still found wild in some parts 

 of India and the Malay Islands. Professor Bateson points 

 out (1913, p. 90) that in Callus hankiva there is no factor for 

 rose comb, pea comb, barring on the feathers, or for the 

 various dominant types of dark plumage. He thinks it 

 improbable that the jungle-fowl could be the ancestor of 

 some of the modern heavy breeds of poultry. But even if 

 his suggestion be correct that some other wild Gallus, now 

 extinct, took part in the genetic history of domestic poultry, 

 it would not affect the general evolutionary fact that the 

 diverse domestic breeds have arisen from one or more wild 

 ancestral species. 



Thus we have the general argument which Darwin 

 elaborated in his ** Variation of Animals and Plants under 

 Domestication " (1868) : If Man has been instrumental in 

 sifting out and fixing all these varieties, say of pigeons and 

 poultry, in a short time, what may not Nature have effected 

 in a very long time ? 



Some of the varieties that have been established are so 

 very extraordinary that one cannot help marvelling that 

 they persist at all, even under man's £egis. In an anatomical 

 study of the hooded fowls of the Houdan breed, Fr. Neumann 



