masses converge is found
similarity or even identity of race, easy gradations from one type to
another; where they diverge most widely in the peninsular extremities of
South America, South Africa and Australia, they show the greatest
dissimilarity in their native races, and a corresponding diversity in
their animal life.[300] Geographical proximity combined with accessibility
results in similarity of human and animal occupants, while a
corresponding dissimilarity is the attendant of remoteness or of
segregation. Therefore, despite the distribution of mankind over the
total habitable area of the earth, his penetration into its detached
regions and hidden corners has maintained such variations as still exist
in the human family.

[Sidenote: Monotonous race type of small area.]

If the distribution of the several races be examined in the light of
this conclusion, it becomes apparent that the races who have succeeded
in appropriating only limited portions of the earth's surface, though
each may be a marked variant of the human family, are characterized by
few inner diversities, either of physical features or culture. Their
subdivisions feel only in a slight degree the differentiating effects of
geographic remoteness, which in a small area operates with weakened
force; and they enjoy few of those diversities of environment which
stimulate variation. They form close and distinct ethnic unities also
because their scant numbers restrict the appearance of variations. The
habitat of the negro race in Africa south of the Sahara, relatively
small, limited in its zonal location almost wholly to the Tropics,
poorly diversified both in relief and contour, has produced only a
retarded and monotonous social development based upon tropical
agriculture or a low type of pastoral life. The still smaller, still
less varied habitat of the Australian race, again tropical or
sub-tropical in location, has produced over its whole extent only one
grade of civilization and that the lowest, one physical, mental and
moral type.[301]

[Sidenote: Wide race distribution and inner diversities.]

The Mongoloid area of distribution, on the other hand, is so large that
it necessarily includes a great range of climates and variety of
geographic conditions. [Maps pages 103 and 225.] Representatives of this
race, reflecting their diversified habitats, show many ethnic
differentiations. They reveal also every stage and phase of cultural
development from th