Correspondence on Biology, etc. 



tion of this fact on Darwinian principles ? If there were 

 not barbarous tribes like the Fuegians, one might imagine 

 America to have been peopled when mankind was somewhat 

 more advanced and more capable of diffusing itself over an 

 entire continent. But I cannot well understand why isola- 

 tion such as accompanies a very low state of social progress 

 did not cause the Neo-tropical and Neo-arctic regions to 

 produce by varieties and Natural Selection two very different 

 human races. May it be owing to the smaller lapse of time, 

 which time, nevertheless, was sufficient to allow of the spread 

 of the representatives of one and the same type from Canada 

 to Cape Horn? Have you ever touched on this subject, or 

 can you refer me to anyone who has ? — Believe me ever most 

 truly yours, Cha. Lyell. 



To Sir C. Lyell 



1867. 



Dear Sir Charles, — ^Why the colour of man is sometimes 

 constant over large areas while in other cases it varies, we 

 cannot certainly tell ; but we may well suppose it to be due 

 to its being more or less correlated with constitutional char- 

 acters favourable to life. By far the most common colour of 

 man is a warm brown, not very different from that of the 

 American Indian. White and black are alike deviations 

 from this, and are probably correlated with mental and 

 physical peculiarities which have been favourable to the in- 

 crease and maintenance of the particular race. I shall infer, 

 therefore, that the brown or red was the original colour of 

 man, and that it maintains itself throughout all climates in 

 America because accidental deviations from it have not been 

 accompanied by any useful constitutional peculiarities. It 

 is Bates's opinion that the Indians are recent immigrants 

 into the tropical plains of South America, and are not yet 

 fully acclimatised.— Yours faithfully, ^ jj Wallace 



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