THE HUMAN SPECIES. 101 



His location in systematic arrangement, and the various con- 

 ditions, physiological and historical, connected with the species, 

 are, therefore, a subject of the highest interest. His primeval 

 position, the region selected, "where history and science can 

 trace his first habitation and development, deserve an attention 

 which it does not seem to have as yet obtained ; for, by investi- 

 gation in that quarter alone, a more correct estimate of the 

 date of his era, anterior to the great superficial disturbances 

 which have occurred on earth, can be arrived at. Hence is 

 drawn the value of a clear view of the facts belonging to the 

 cavern and loam deposits of organic remains, without, as well 

 as with, human bones, and the so-called petrified skeletons of 

 man which have been detected on various occasions. Hence, 

 also, the interest attached to the changes which have occurred 

 on the earth's surface, because they may have had a para- 

 mount influence on the primeval distribution of man, and con- 

 stitute the only additional question which philosophical research 

 can attach to the primordial history of the human species. At 

 a later period, minor catastrophes, and the action of human 

 passions, led to known migrations by sea, and to the progress 

 of colonization by land. If the most remote were causes of the 

 approximation of different species of man, or of the separation 

 of the three great varieties of the human race, taken as a single 

 species, the later were most certainly the source of the minor 

 distinctions which do exist, both between nations of different 

 , and of the same original stem. 

 Although the question of the unity of species, — that is, 

 whether mankind is to be regarded as a genus, constituted of 

 three or more species, or as only one, composed of as many or 

 of a greater number of varieties, subdivided into races, — may 

 never be positively decided, it will not the less remain an 

 inquiry of intense interest to trace the several conditions, which, 

 in zoology, are assumed to have a preponderating influence. 

 Therefore, researches directed to the questions whether the 

 differences of conformation are sufficient in their anatomical 

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