Humans have lived in the Peruvian Andes for about 12,000 years providing adequate time for adaptation to high altitude to have occurred. The arrival of the Spanish conquistadors in the 16th century potentially altered this process through genetic admixture. Early records revealed a potential for reduced fertility and a high perinatal and neonatal mortality amongst the early Spanish inhabitants who settled at high altitude when compared to the native Inca population. It appears that fertility is reduced during acute exposure at high altitude but is normal in populations born and living at high altitude. On the other hand, perinatal and neonatal mortality is presently still high at elevated altitudes, even after taking into account socio-economic status. The rates of perinatal and neonatal mortality are, however, lower in populations that have resided at high altitude for longer; populations inhabiting the southern Andes have a longer antiquity at high altitude and lower rates of fetal and neonatal deaths than those in the central Andes with a shorter residence at high altitude. Clearly, antiquity and genetics are important components in determining survival and quality of life at high altitude. © 2007 Elsevier B.V. All rights reserved.