A MULTINATIONAL ANDEAN GENETIC AND HEALTH PROGRAMME: A STUDY OF ADAPTATION TO THE HYPOXIA OF ALTITUDE

Twelve thousand years ago, possibly earlier, man appeared in the highlands of South America near Ayacucho (MacNeish, Berger, and Protsch, 1970). Assuming the prehistoric migrants to the Americas arrived over the Bering land bridge, the descendants of some had made their way surprisingly rapidly to South America and to one of the more inhospitable regions of the New World, an area which differs strikingly in oxygen tension, humidity and temperature from most of the land through which they must have passed. We know virtually nothing of the physical appearance of these individuals, and are not even certain whether they merely frequented the altiplano in search of game—only their tools have been found, which might suggest this to be so—or resided there permanently. We do know, however, that individuals accustomed to the levels of oxygen which obtain at or near sea level when transported to this altitude are apt to experience one or some combination of the following: shortness of breath, dizziness and marked palpitation upon exertion, exhilaration, sleeplessness, headache, the irregularity of respiratory rhythm known as Cheyne–Stokes breathing, impairment of mentation, diminished night visual acuity, accelerated pulse as well as other less obvious signs (Buskirk, 1971). Ultimately, however, within days or weeks at most, an accommodation is made, and one’s normal activity level can again be achieved without undue physical stress or apprehension. The process by which this occurs is termed acclimatization to distinguish it from the adjustment which proceeds over generations and is commonly known as adaptation. Conspicuous changes associated with acclimatization are an increase in haemoglobin and circulating red blood cells, and to a smaller degree behaviour modification, a tendency to hyperventilate and initially at least to husband energy.