groups than pastoral hordes. Hence shepherd folk are found in their
purest types in deserts and steppes, where conditions early crystallized
the social form and checked development. [Rainfall map chap. XIV.]

[Sidenote: Native animal and plant life as factors.]

Adverse conditions of climate and soil are not the only factors in this
retardation. The very unequal native equipment of the several continents
with plant and animal forms likely to accelerate the advance to nomadism
and agriculture also enters into the equation. In Australia, the lack of
a single indigenous mammal fit for domestication and of all cereals
blocked from the start the pastoral and agricultural development of the
natives. Hence at the arrival of the Europeans, Australia presented the
unique spectacle of a whole continent with its population still held in
the vise of nature. The Americas had a limited variety of animals
susceptible of domestication, but were more meagerly equipped than the
Old World. Yet the Eskimo failed to tame and herd the reindeer, though
their precarious food-supply furnished a motive for the transition.
Moreover, an abundance of grass and reindeer moss (_Cladonia
rangiferina_), and congenial climatic conditions favored it especially
for the Alaskan Eskimo, who had, besides, the nearby example of the
Siberian Chukches as reindeer herders.[117] The buffalo, whose
domesticability has been proved, was never utilized in this way by the
Indians, though the Spaniard Gomara writes of one tribe, living in the
sixteenth century in the southwestern part of what is now United States
territory, whose chief wealth consisted in herds of tame buffalo.[118]
North America, at the time of the discovery, saw only the dog hanging
about the lodges of the Indians; but in South America the llama and
alpaca, confined to the higher levels of the Andes (10,000 to 15,000
feet elevation) were used in domestic herds only in the mountain-rimmed