acclimation

Physiological changes induced in an organism by exposure to new environmental conditions. When humans move to higher altitudes, for example, the number of red blood cells rises to increase the oxygen-carrying capacity of the blood in order to compensate for the lower levels of oxygen in the air.

In evolutionary terms, the ability to acclimate is an important adaptation as it allows the organism to cope with the environmental changes occurring during its lifetime.

Humans have proved their ability to acclimate by spreading over many parts of the world from a single source (for example, the Jews, British and Dutch colonists, Africans in the New World). However, acclimation is not always successful, and diseases that are comparatively harmless to natives of a country frequently prove fatal to strangers. In France a society was founded 1854 by Isidore Geoffroy Saint-Hilaire for the practical and theoretical study of this subject, and the Société Nationale d'Acclimatation has adapted species and receives assistance from the Jardin Zoologique d'Acclimatation. London has the Zoological Gardens and Kew Gardens, in which acclimation can be seen in animals and plants respectively.