7 - Migration and adaptation

Summary

Introduction

Adaptation to the environment

Migration or movement as a means of behavioural adaptation to environmental stress is a fundamental property of all mobile forms of life. Human populations are characterized as highly mobile, not only because of their long palaeolithic existence as nomadic hunters and gatherers, but also because of the worldwide movements following the age of exploration and the widespread migration occurring today (Davis, 1974; Clarke, 1984). The effects of these population movements on populations of origin, migrants themselves, host populations, and each of their respective environments are complex and still not fully understood (Lee, 1966; Graves & Graves, 1974; Robins, 1981; Baker & Baker, 1984). We do know that although humans' motives for moving are usually to improve their lives or the lives of their children, the new environments to which they are exposed are often stressful and carry high risks of illness and death. The reasons for these high risks are manifold, but are based fundamentally on the migrants' lack of adaptation to the new environment.

Within the framework of evolutionary and adaptation theory, there are a number of general principles that will assist in the understanding of the biological effects of migration. First, populations with relatively stable social and subsistence systems and which have been long resident in a given area have adapted in their biology, population structure and sociocultural system to this area and its environment.