Published online by Cambridge University Press: 05 August 2012
INTRODUCTION
Ever since hominids left Africa, they have expanded throughout the world and have adapted to diverse environments, and acquired specific biological and cultural traits that have enabled them to survive in a given area. The conceptual framework of research in biological anthropology is that evolutionary selection processes have produced the human species and that these processes have produced a set of genetic characteristics, which adapted our evolving species to their environment. Current investigations have demonstrated that the phenotype measured morphologically, physiologically, or biochemically is the product of genetic plasticity operating during development. Within this framework, it is assumed that some of the biological adjustments or adaptations people made to their natural and social environments have also modified how they adjusted to subsequent environments. The adjustments we have made to improve our adaptations to a given environment have produced a new environment to which we, in turn, adapt in an ongoing process of new stress and new adaptation.
HOMEOSTASIS AND ENVIRONMENTAL STRESS
Central to the study of adaptation is the concept of homeostasis and environmental stress. Environmental stress is defined as any condition that disturbs the normal functioning of the organism. Such interference eventually causes a disturbance of internal homeostasis. Homeostasis means the ability of the organism to maintain a stable internal environment despite diverse, disruptive, external environmental influence (Proser, 1964). On a functional level, all adaptive responses of the organism or the individual are made to restore internal homeostasis.
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