other. Neither bio-geography nor
anthropo-geography can adopt the continents as geographical provinces,
although floras, faunas and races the world over give evidence of
partial or temporary restriction to a certain continent, whence they
have overflowed to other lands. A ground-plan for the geographical
classification of races is to be found, as Tylor says, in the fact that
they are not found scattered indiscriminately over the earth's surface,
but that certain races belong to certain regions, in whose peculiar
environment they have developed their type, and whence they have spread
to other lands, undergoing modifications from race intermixture and
successive changes of environment on the way.[770]

[Sidenote: Contrast of the northern and southern continents.]

From this general law of race movements it follows that certain groups
of land-masses, favored by location and large area, play a great
imperial role, holding other lands as appanages. The Eastern Hemisphere,
as we have seen, enjoys this advantage over the Western. Still more the
Northern Hemisphere, blessed with an abundance of land and a predominant
Temperate Zone location, is able to lord it over the Southern, so
insular in its poverty of land. The history of the Northern Hemisphere
is marked by far-reaching historical influences and wide control; that
of the Southern, by detachment, aloofness and impotence, due to the
small area and isolation of its land-masses. A subordinate role is its
fate. Australia will always follow in the train of Eurasia, whence alone
it has derived its incentives and means of progress. Neither the
southern half of Africa nor South America has ever in historical times
struck out a road to advancement unaided by its northern neighbors.
Primitive South America developed the only independent civilization that
ever blossomed in the Southern Hemisphere, but the Peruvian achievements
in progress were inferior to those of Mexico and Central America.[771]

[Sidenote: Isolation of the southern continents.]

This subordination of the southern continents is partly due to the fact
that they have only one side of contact or neighborhood with any other
land, that is, on the north; yet even here the contact is not close. In
Australia the medium of communication is a long bridge of islands; in
America, a winding island chain and a mountainous isthmus; in Africa, a
broad zone of desert dividing the Mediterranean or Eurasian from the
tropical and N