High altitude hypoxia and reproduction: is there an environmental limit to the human male reproductive system?

Adaptation to the environment is characterized by the search for favorable solutions to survival and it must include the ability of the species to reproduce. We suggest that, in the absence of adaptation, humans are not capable to reproduce in extreme altitudes. On the contrary, it is clear that the absence of the negative effects of chronic hypoxia in human male reproduction, erectile function and fertility, in populations indigenous to high altitude, argues that these populations have adapted to the conditions at high altitude.