to determine whether this were due to climate alone, or to the defective nutrition which too often attends a poverty of environment. It is a well-recognized law in the geographical distribution of lower forms of life that two hundred and fifty feet increase in altitude is equivalent to one degree's remove in latitude from the equator. If this be true, applied to man, it would lead us to expect a steady increase of blondness toward the north of Europe, a fact which all our maps have substantiated fully. Experience in colonizing Africa to-day indicates that such adaptation of the Teutonic race to a northern climate constitutes a serious bar to its re-entry into the equatorial regions.[1] May not this change physiologically be correlated in some way with the modified pigmentation? We should assume, in other words, that as the primitive long-headed type of the stone age gradually spread over northern Europe, environmental influences slowly, very slowly, through scores of generations, would lead this subvariety to emerge. Its differentiation would then be commensurate with the distance from its original southern center of migration—whether a direct product of environment or merely indirectly through natural selection is not for us to determine as yet.
Climate as an explanation for the derived blondness of the Teutonic race is, however, not sufficient by itself to account for the phenomenon. It neglects a significant fact on which we laid emphasis in an earlier chapter, viz., that blondness not only decreases as we proceed southward from Scandinavia, but in an easterly direction as well. In other words, the Russians at the latitude of Norway and Sweden are far more brunette in type. How shall we reconcile this with our environmental hypothesis? In the first place, the hordes which speak the Slavic languages are all comparatively recent immigrants in Europe; they are physically allied to the broad-headed Alpine type. This we shall explain in a succeeding paragraph. For this reason, comparisons between Scandinavia and the lands directly east of it are vitiated at once. But there is yet another reason why we may expect these Teutons to be notable even in their own latitude by reason of their blondness. It is this; that the trait has for some reason become so distinctive of a dominant race all over Europe that it has been rendered susceptible to the influence of artificial selection. Thus a powerful agent is allied to climate to exaggerate what may once have been an insignificant trait. Were there space we might adduce abundant evidence to prove that the upper classes in France, Germany, Austria, and the British Isles are distinctly lighter in hair and eyes than the peasantry,[2] The classical
