EVOLUTION IN NATURE AND UNDER DOMESTICATION. 233 



domestic dogs, because wild Canidae have been repeatedly do- 

 mesticated and because hybrids between dogs and different 

 wild canidae have proved fertile. 



The groups of domestic animals for which Darwin assumed a 

 monophyletic origin are the fowl, the pigeon, the rabbit and 

 the canary. The reasons which led Darwin to a belief in a mon- 

 ophyletic origin of all the domestic breeds of tame fowls were 

 the following. No wild fowl now exists which exhibits the very 

 marked peculiarities of very many tame breeds, such as the 

 Dorking's fifth-toe, the feathered-crest of the Polish, the frizz- 

 led feathers of some Japanese bantams. 



All the tame chickens are mutually fertile, they all have ap- 

 proximately the same voice and in most breeds there are sub- 

 breeds coloured like the wild Gallus bankiva. 



Is it possible, in the light of the experimental evidence which 

 has become known since Darwin, to maintain the possibility 

 that all the tame fowls descend from one wild species? I think 

 not. No wild species by itself has a potential variability suffic- 

 ient to account for the variability in the tame chickens. Let us 

 examine Darwin's ground for a belief in the monophyletic ori- 

 gin of the tame breeds in detail. 



In the first place it is undoubtedly true, that no wild chick- 

 ens with five toes, or upturned feathers, exist. We must not for- 

 get that Darwin's thesis, that all tame chickens originated from 

 one species was originally meant to refute the idea of the fan- 

 ciers that, every tame breed descended from a separate, now 

 extinct, wild species. Even comparatively recently it was 

 urged by Davenport that the Malay breed must have originated 

 from a species, different from that from which all the other 

 chickens descended. As far as it goes, Darwin's view is the more 

 logical one. 



But, and this to our mind is the most important new fact 

 bearing upon the problem, we now know that cross-breeding 

 produces absolutely new characters. Just as we saw double- 

 flowers and fimbriation, and polycephaly result from a cross 

 between two species of Argemone, and just as we saw waltzing 



