ces the utilization of
all the available area, and thereby in every locality stimulates
adaptation to environment.

[Sidenote: Adaptability of man to climatic extremes.]

Man ranks among the most adaptable organic beings on the earth. No
climate is absolutely intolerable to him. Only the absence of food
supply or of all marketable commodities will exclude him from the most
inhospitable region. His dwellings are found from sea level up to an
altitude of 5000 meters or more, where the air pressure is little over
one half that on the coast.[1412] Seventeen per cent. of the towns and
cities of Bolivia are located at an elevation above 13,000 feet (4000
meters), while Aullagas occupies a site 15,700 feet or nearly 5000
meters above the sea.[1413] Mineral wealth explains these high Bolivian
settlements, just as it draws the Mexican sulphur miners to temporary
residence in the crater of Popocatepetl at an altitude of 17,787 feet
(5420 meters), from their permanent dwellings a thousand meters
below.[1414] The laborers employed in the construction of the Oroya
railroad in Peru became rapidly accustomed to work in the rarefied air
at an elevation of 4000 to 4800 meters. The trade routes over the Andes
and Himalayan ranges often cross passes at similar altitudes; the
Karakorum road mounts to 18,548 feet (5,650 meters). Yet these great
elevations do not prevent men going their way and doing the day's work,
although the unacclimated tenderfoot is liable to attacks of mountain
sickness in consequence of the rarefied air.[1415]

Man makes himself at home in any zone. The cold pole of the earth, so
far as recorded temperatures show, is the town of Verkhoyansk in
northeastern Siberia, whose mean January temperature is 54 F. below zero
(-48 Centigrade). Massawa, one of the hottest spots in the furnace of
Africa is the capital of the Italian colony of Eritrea. However,
extremes both of heat and cold reduce the density of population, the
scale and efficiency of economic enterprises. The greatest events of
universal history and especially the greatest historical developments
belong to the North Temperate Zone. The decisive voyages of discovery
emanated thence, though the needs of trade and the steady winds of low
latitudes combined to carry them to the Tropics. The coldest lands of
the earth are either uninhabited, like Spitzenbergen, or sparsely
populated, like northern Siberia. The hottest regions, also, are far
from being so densely p