titles of blubber and oil; and his digestive system, heavily taxed in providing the wherewith to meet excessive loss by radiation, supplies less material for other vital purposes. This great physiological cost of individual life, indirectly checking the multiplication of individuals, arrests social evolution.
A kindred relation of cause and effect is shown us in the Southern Hemisphere by the still more miserable Fuegians. Living nearly unclothed in a region of continual storms of rain and snow, which their wretched dwellings of sticks and grass do not exclude, and having little food but fish and mollusks, these beings, described as scarcely human in appearance, have such difficulty in preserving the vital balance in face of the rapid escape of heat, that the surplus for individual development is narrowly restricted, and, by consequence, the surplus for producing and rearing new individuals. Hence the numbers remain too small for exhibiting any thing beyond incipient social existence.
Though, in some tropical regions, an opposite extreme of temperature so far impedes the vital actions as to impede social development, yet hindrance from this cause seems exceptional and relatively unimportant. Life in general, and mammalian life along with it, is great in quantity as well as individually high, in localities that are among the hottest. The inertness and silence during the noontide glare in such localities do, indeed, furnish evidence of enervation; but in cooler parts of the twenty-four hours there is a compensating energy. And if it is true that varieties of the human race, adapted to these localities, show us, in comparison with ourselves, some indolence, this does not seem greater than, or even equal to, the indolence of the primitive man in temperate climates.
Contemplated in the mass, the facts do not countenance the current idea that great heat hinders progress. Many societies have arisen in hot climates, and in hot climates have reached large and complex growths. All our earliest recorded civilizations belonged to regions which, if not tropical, almost equal the tropics in height of temperature. India and Southern China, as still existing, show us great social evolutions within the tropics. And, beyond this, the elaborate architectural remains of Java and of Cambodia yield proofs of other tropical civilizations in the East; while the extinct societies of Central America, Mexico, and Peru, need but be named to make it manifest that in the New World, also, there were in past times great advances in hot regions.
It is thus, too, if we compare societies of ruder types that have developed in warm climates, with allied societies belonging to colder climates. Tahiti, the Tonga Islands, and the Sandwich Islands, are within the tropics; and in them, when first discovered, there had been reached stages of evolution that were remarkable considering the absence of metals. So that, though excessive heat hinders the
