100 NATURAL SELECTION v 



When once a particular mode of building has been adopted, 

 and has become confirmed by habit and by hereditary custom, 

 it will be long retained, even when its utility has been lost 

 through changed conditions, or through migration into a very 

 different region. As a general rule, throughout the whole 

 continent of America, native houses, when permanent, are 

 built directly upon the ground strength and security being 

 given by thickening the low walls and the roof. In almost 

 the whole of the Malay Islands, on the contrary, the houses 

 are raised on posts, often to a great height, with an open 

 bamboo floor ; and the whole structure is exceedingly slight 

 and thin. Now, what can be the reason of this remarkable 

 difference between countries, many parts of which are 

 strikingly similar in physical conditions, natural productions, 

 and the state of civilisation of their inhabitants ? We appear 

 to have some clue to it in the supposed origin and migrations 

 of their respective populations. The indigenes of tropical 

 America are believed to have immigrated from the north 

 from a country where the winters are severe, and raised 

 houses with open floors would be hardly habitable. They 

 moved southwards by land along the mountain ranges and 

 uplands, and in an altered climate continued the mode of 

 construction of their forefathers, modified only by the new 

 materials they met with. By minute observations of the 

 Indians of the Amazon Valley, Mr. Bates arrived at the 

 conclusion that they were comparatively recent immigrants 

 from a colder climate. He says : " No one could live long 

 among the Indians of the Upper Amazon without being 

 struck with their constitutional dislike to the heat. . . . Their 

 skin is hot to the touch, and they perspire little. . . . They 

 are restless and discontented in hot, dry weather, but cheerful 

 on cool days, when the rain is pouring down their naked 

 backs." And, after giving many other details, he concludes, 

 " How different all this is with the Negro, the true child of 

 tropical climes ! The impression gradually forced itself on 

 my mind that the Red Indian lives as an immigrant or 

 stranger in these hot regions, and that his constitution was 

 not originally adapted, and has not since become perfectly 

 adapted, to the climate." 



The Malay races, on the other hand, are no doubt very 



