The Epidemiology of Migration
PHILIP D. CURTIN
MANY NATURAL conditions have limited the human freedom to move from one part of the world to another. The land bridge across the present Bering Straits made possible the peopling of the Americas, but only briefly. The Americas were again isolated until the seafarers like the Inuit and the Norse began to use northern routes of entry from east and west, and the isolation was not definitively ended until the Columbian breakthrough across the Atlantic. But transportation was not the only physical limitation on movement. The geography of disease and human immunities to disease has also been an important background factor, even when it was not clearly understood.
Disease and Migration
It is generally recognized that migration almost always exacts a price in increased morbidity and mortality from disease. That price was much higher in centuries past than it is today, but it is still with us in attenuated form. The price in increased death and disease could be exacted in various ways—from the migrants, from the receiving society, or from both. The high death rate of Europeans moving to the tropics is a well-known instance of the price paid by the migrants. The death of the American Indians from exotic diseases is the best known and most spectacular instance of damage to the receiving society. The precise extent of the die-off is subject to continuing controversy, but we know that the American Indian population in the region of most intense contact dropped by at least half within a century.
Nor is the phenomenon confined to movement over distances we