LARGER PROBLEMS OF ANTHROPOLOGY 465 



When practical anthropology arose in America, it was seen by 

 Gallatin and Morgan and other pioneers that languages and social 

 usages tend to spread among contiguous tribes; and as Indian 

 students advanced, it was perceived that the tendency toward 

 activital interchange extended also to arts and industries and 

 myths, and had, indeed, resulted in the development of powerful 

 federations (somewhat miscalled "nations"), such as the Iroquois 

 League and the Dakota Confederacy. Meantime it was observed 

 that the spontaneous interchange of words and weapons, usages 

 and utensils, with contiguous tribes was sooner or later accom- 

 panied by intermarriage, so that blood and culture blent at once. 

 Of course this observation merely reflected the unwitting experi- 

 ence of every generation among every people in every land; but, 

 made as it was under the stress of practical problems of polity 

 and peace, it awakened consciousness and the law of convergent 

 development among mankind was grasped. Once realized, the 

 law was found of wide application; it was perceived that black 

 folk are not growing blacker, nor brown men browner, nor red 

 tribesmen redder, because (among other reasons) some interchange 

 of culture and blood begins with first contact and increases with 

 time, until at least some of the leaven of the highest humanity 

 pervades the lump, while the ideals and standards of all progress 

 toward unity; it was perceived that the types of Homo sapiens 

 (i. e., the "races" of mankind) are not differentiating, because of 

 that irresistible mimetic impulse which is the mainspring of eleva- 

 tion, especially among the lower and measurably among the higher; 

 it was perceived that culture is fertilized by contact with other 

 culture more effectively than in any other fashion; and it was 

 perceived that when the initial differences are not too great, blood 

 fertilizes blood in such wise that the vigor of a people may be meas- 

 ured by the complexity of their interwoven strains that Briton 

 yesterday and American to-day led and still lead the world because 

 the blood of each streamed up from a more varied group of vigor- 

 ous sires than that of any earlier scion. The themes of culture- 

 union and blood-blending are too broad and deep for treatment 

 in a paragraph; yet it must be affirmed, with an emphasis which 

 can hardly be made too strong, that these are the dominant fac- 

 tors of human development, and that this development, so far as 

 actually observed, is always convergent, never divergent. 



Now it is a logical corollary of the law of convergent develop- 

 ment that mankind were originally more diverse than now, and 

 hence that there must have been several loci, or centres, of human 

 origin; and this corollary leads to a theory of polygenesis, which 

 has been much discussed during a decade or two. Some of the 

 polygenesists, like Keane, are content with four original stocks, 



