The Role of Human Skin Color and Body Heat Conductivity in Adaptation to Hot and Cold Climates

Abstract

As is known Homo s. sapiens is the only living creature that has managed to inhabit the whole of the Earth, while remaining a single tropical biological species. The case is really unique considering that all this happened in an unprecedentedly short (by evolutionary scale) period of time, if the beginning of this process is considered to be its exit outside of East Africa about 30 000 - 50 000 years ago. However, science does not know everything about how all this happened to a species that itself emerged relatively recently (130 000 - 200 000 year ago) and nevertheless managed to do what other species failed to do. One of the important questions that arises when comprehending this phenomenon is reduced to the following: what features of a human him to make such an unprecedented breakthrough in the settlement of the planet? In particular, what biological advantages or prerequisites did the ancestors of modern man possess when they decided to leave Africa? Usually, such advantages include its large neocortex with a high-functioning mind, high physiological plasticity, perfect system of physiological thermoregulation, the structural features of the upper limbs, unique sexual and reproductive behavior, etc., etc. Without disputing the importance of these well-studied advantages, we would like to add to this list two more that could play an important role in the settlement of all climatogeographic zones of Africa and Eurasia by man: variability of the skin color and the level of heat conductivity of his body. We believe that the skin color and the heat-conducting ability of the human body are involved in his adaptation to heat and cold climates through thermoregulation systems. After all, the skin is the largest human organ that is in direct contact with the ambient temperature.