The present study reports the results of erythrocyte antigen typing for the following systems: ABO, MN, Rh, Kell, Duffy, and Diego in roughly 180 Atacamefio Indians from the oasis of Toconao, northern Chile. A subsample was tested for variation at the histocompatibility loci A, B, and C. Results agree with previous findings based on smaller samples. Caucasian admixture of the Atacameiios from Toconao was estimated to be 0.056 & 0.022.
As part of a broader study whose general aims are to quantify the participation of evolutionary factors in the microdifferentiation of Andean aborigines and to assess their genetic response to drugs and environmental agents, the population of the oasis of Toconao in the Atacama desert was surveyed in March of 1983.
The Atacama desert is located in northern Chile between lat. 19 S and lat. 27 S. Only one permanent river, the Loa, reaches the Pacific Ocean in this area, which is supposed to be one of the driest deserts on earth. The western slopes of the Andes are bare to about 2.500 m. In the lower mountain region a few oases have been inhabited by men for at least 10,000 years, as judged by archaeological findings (Bittmann et al., 1978). The Atacameiios' cultural elaboration began at about the start of the Christian era. Subsequently, they received the influences of the highland cultures of Tiwanaku around 600 AD and Inca at 1400 AD. The area was invaded by the Spanish in 1536, first under the command of Diego de Almagro, and 4 years later under Pedro de Valdivia and Francisco de Aguirre. The Spanish conquest was consolidated in 1557 through a treaty (Hidalgo, 1981).
Toconao, located at 2,500 m of altitude, was founded in 1557 by Juan Velasquez Altamirano, but archaeological evidence indicated that the oasis has been inhabited since prehistoric times (Hidalgo, 1981). The Atacame-