498 NATURAL HISTORY OF MAN. 



in adjoining regions and on the same continents, which are 

 observed even where the species are distinct. It cannot be 

 doubted that geological changes in the globe, and parti- 

 cularly the relative changes of sea and land, have been 

 largely concerned in the present distribution of organic life, 

 by altering climate, and separating genera and species con- 

 nected primitively with common centres. In Sir C. Ly ell's 

 work there is an admirable account of those conditions which 

 probably have determined the various distribution of species ; 

 closely limiting the locality of some, enabling others to 

 occupy large tracts of the earth's surface or of the waters of 

 the ocean. This will at once be noted as a fundamental part 

 of the enquiry. On the one hand, while pointing at the ori- 

 ginal singleness of locality for every species, it indicates their 

 diffusion or limitation as depending on the capacities of each 

 for undergoing deviations which enable them to sustain 

 changes of climate, food, and other conditions of life. On 

 the other hand, it indicates the effect of these altered con- 

 ditions of existence acting on certain parts of the animal 

 structure and economy, and modifying them within the limits 

 of change prescribed to each species ; thus completing the 

 circle of demonstration required. 



Following, then, this great line of analogy from inferior 

 species, we are led to infer that Man also had his origin in a 

 single and definite place on the earth; whence he has 

 diffused himself more widely over its surface than any other 

 species, by virtue of those eminent faculties of mind, as well 

 as body, which enable him to meet even the extreme con- 

 tingencies of climate and food, and to adapt his existence 

 more variously to the circumstances around him. Man can 

 clothe himself, can fit his habitation to the climate, *can 

 prepare his food by cookery, can provide artificial means of 

 transport, and, above all, can communicate to his fellow-men 

 by articulate speech. In the simple expression of these 



