My great fault is haste.  An idea strikes me, I think over it for a few days, and then write away with such illustrations as occur to me while going on.  I therefore look at the subject almost solely from one point of view.  Thus in my paper on Man[41] I aim solely at showing that brutes are modified in a great variety of ways by Natural Selection, but that in none of these particular ways can man be modified, because of the superiority of his intellect.  I therefore no doubt overlook a few smaller points in which Natural Selection may still act on men and brutes alike.  Colour is one of them, and I have alluded to this in correlation to constitution in an abstract I have made at Sclater’s request for the Natural History Review.[42] At the same time, there is so much evidence of migrations and displacements of races of man, and so many cases of peoples of distinct physical characters inhabiting the same or similar regions, and also of races of uniform physical characters inhabiting widely dissimilar regions, that the external characteristics of the chief races of man must I think be older than his present geographical distribution, and the modifications produced by correlation to favourable variations of constitution be only a secondary cause of external modification.

I hope you may get the returns from the Army.  They would be very interesting, but I do not expect the results would be favourable to your view.

With regard to the constant battles of savages leading to selection of physical superiority, I think it would be very imperfect, and subject to so many exceptions and irregularities that it could produce no definite result.  For instance, the strongest and bravest men would lead, and expose themselves most, and would therefore be most subject to wounds and death.  And the physical energy which led to any one tribe delighting in war might lead to its extermination by inducing quarrels with all surrounding tribes and leading them to combine against it.  Again, superior cunning, stealth and swiftness of foot, or even better weapons, would often lead to victory as well as mere physical strength.  Moreover this kind of more or less perpetual war goes on among all savage peoples.  It could lead therefore to no differential characters, but merely to the keeping up of a certain average standard of bodily and mental health and vigour.  So with selection of variations adapted to special habits of life, as fishing, paddling, riding, climbing, etc. etc., in different races:  no doubt it must act to some extent, but will it be ever so rigid as to induce a definite physical modification, and can we imagine it to have had any part in producing the distinct races that now exist?