At a somewhat later period there began to arrive in the New World groups of Mongoloids coming by the same route as their predecessors. Many of these were probably purely Mongoloid in race, but others were mixed with some other racial element notable because of its high-bridged and often convex nose. This may have been either Armenoid or Proto-Nordic (or neither one). These later invaders were capable of higher cultural development than the early pioneers and were responsible for the development of agriculture and for the notable achievements of the New World civilization. In some places they may have driven out and supplanted the early long-heads, but often they seem to have interbred with them producing the multiple and varied types of the present American Indians—types which are Mongoloid to a varying extent, but never purely Mongoloid. Last of all came the Eskimo, a culturally primitive Mongoloid group, already mixed with some non-Mongoloid strain before their arrival in North America.[5] In 1947 Hooton stated this in simpler terms: “I am fairly sure that the earliest arrivals here were non-Mongoloids carrying archaic White strains (‘Australoids,’ if you like) probably mixed with Negritic elements and with whatever else was kicking around in Asia before they crossed Bering Strait.”[6] Dixon’s position, which he took in 1923, is in some ways a more radical one than Hooton’s. He introduces “Proto-Australoid,” “Proto-Negroid,” and Mediterranean elements, and also Caspian and Alpine; but, where Hooton recognizes a general stock in which Australoid, Negroid, and Mediterranean were blended before their arrival, Dixon brings in his races separate and pure, and he assigns them definite areas in the New World.