That these ancient peoples were of the American race 
is not questioned. The causes and conditions which 
initiated the upward trent of the culture, whether wholly 
autochthonous or built on germs of foreign provenance, 
whether developed in the region or on the sites now occu- 
pied by the great ruined cities or elsewhere, or whether 
climatic conditions corresponded to those of the present, 
are subjects for conjecture and problems for research. 
