Alfred Russel Wallace 



would be increased by selection. I see no reason to believe 

 that species (usually) have been isolated first and modified 

 afterwards, but rather that new species usually arise from 

 species which have a wide range, and in different areas need 

 somewhat different characters and habits. Then distinctness 

 arises both by adaptation and by development of recognition 

 marks to minimise intercrossing. 



I wonder Darwin did not see that if the unknown " con- 

 stant causes " he supposes can modify all the individuals of 

 a species, either indifferently, usefully, or hurtfully, and that 

 these characters so produced are, as Romanes says, very, 

 very numerous in all species, and are sometimes the only 

 specific characters, then the Neo-Lamarckians are quite right 

 in putting Natural Selection as a very secondary and sub- 

 ordinate influence, since all it has to do is to weed out the 

 hurtful variations. 



Of course, if a species with warning colours were, in part, 

 completely isolated, and its colours or markings were acci* 

 dentally different from the parent form, whatever set of 

 markings and colours it had would be, I consider, rendered 

 stable for recognition, and also for protection, since if it 

 varied too much the young birds and other enemies would 

 take a heavier toll in learning it was uneatable. It might 

 then be said that the character by which this species differs 

 from the parent species is a useless character. But surely 

 this. is not what is usually meant by a " useless character." 

 This is highly useful in itself, though^,the difference from 

 the other species is not useful. If they 'were in contact it 

 would be useful, as a distinction preventing intercrossing, 

 and so long as they are not brought together we cannot really 

 tell if it is a species at all, since it might breed freely with 

 the parent form and thus return back to one type. The 

 ^' useless characters " I have always had in mind when argu- 

 ing this question are those which are or are supposed to be 



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