In hot, humid climates people tend to have small bodies with slender limbs. This explains why the pygmies of equatorial Africa and South America have evolved as they have. Long, thin noses help to warm and humidify the air as it is inhaled, and are more common in colder regions. Broad short noses are associated with tropical environments . Whether a person is black, white or yellow Sun tanning increases the melanin levels in the skin to the same degree, we do not notice this in dark skinned individuals as there is only a small change in absolute light reflectance.
Few mammals can stay active in the hottest parts of world as well as humans can.
This is because of our extremely efficient sweating mechanism. But in extreme cold total vasoconstriction can lead to frost bite.