rtificial selection by the emigration of
the taller and more robust individuals, but in considerable part to the
harsh climate and starvation food-yield of that sterile soil; for the
children of the region, if removed to the more fertile valleys of the
Loire and Garonne, grow to average stature.[40] The effect of a scant and
uncertain food supply is especially clear in savages, who have erected
fewer buffers between themselves and the pressure of environment. The
Bushmen of the Kalahari Desert are shorter than their Hottentot kindred
who pasture their flocks and herds in the neighboring grasslands.[41]
Samoyedes, Lapps, and other hyperborean races of Eurasia are shorter
than their more southern neighbors, the physical record of an immemorial
struggle against cold and hunger. The stunted forms and wretched aspect
of the Snake Indians inhabiting the Rocky Mountain deserts distinguished
these clans from the tall buffalo-hunting tribes of the plains.[42] Any
feature of geographic environment tending to affect directly the
physical vigor and strength of a people cannot fail to prove a potent
factor in their history.

[Sidenote: Physical effects of dominant activities.]

Oftentimes environment modifies the physique of a people indirectly by
imposing upon them certain predominant activities, which may develop one
part of the body almost to the point of deformity. This is the effect of
increased use or disuse which Darwin discusses. He attributes the thin
legs and thick arms of the Payaguas Indians living along the Paraguay
River to generations of lives spent in canoes, with the lower
extremities motionless and the arm and chest muscles in constant
exercise.[43] Livingstone found these same characteristics of broad
chests and shoulders with ill-developed legs among the Barotse of the
upper Zambesi;[44] and they have been observed in pronounced form,
coupled with distinctly impaired powers of locomotion, among the
Tlingit, Tsimshean, and Haida Indians of the southern Alaskan and
British Columbia coast, where the geographic conditions of a mountainous
and almost strandless shore interdicted agriculture and necessitated
sea-faring activities.[45] An identical environment has produced a like
physical effect upon the canoemen of Tierra del Fuego[46] and the
Aleutian Islanders, who often sit in their boats twenty hours at a
time.[47] These special adaptations are temporary in their nature and
tend to disappear with change of occupat