ABSTRACT
Physiological feature of man which is related to his environment is that many of his vital functions affecting his performance are geared according to his circadian rhythms. These rhythms are in turn cued to the shift between light and darkness as a consequence of the rotation of the earth. The geological features of the region would indicate that the natural sources were low in iodine. The fact that man was made to stand on his feet and to lead an upright existence in the force of gravity is also evident from what happens to him when he is put to bed and subjected to uninterrupted horizontal bed rest for 3 to 6 weeks. The physiological and biochemical processes underlying people performance are temperature dependent. The barometric pressure at a given altitude depends on the weight of the air column over the point in question. The atmosphere is compressed under its weight.
