Heat is one of the few stressors that man is unlikely to change. It is an entirely outside force that gives life and destroys it at the same time. Homeostasis helps us maintain our internal equilibrium or stability.  Disturbing our internal equilibrium can result in death. Bodies function on a constant basis and overheating your system is often deadly. Uncontrollable infections can cause the body to overheat. There are also internal forces that create heightened heat elevations to fatal levels.      Humans have an entirely internal temperature regulating system. People have developed cultural patterns and technologies that help them adjust to extremes of temperature and humidity. Too much humidity combined with high heat can not only lead to hyperthermia, but humidity also makes it difficult for the body to evaporate its excess heat. Hyperthermia is the result of our core temperatures rising about 105 to 107 degrees.  Humans can exist only for a short period of time before their temperatures result in deterioration of internal organs and eventually death. Our body shapes and sizes are significant factors in how physiologically our bodies adjust to hot temperatures.  

            Interesting examples of are provided when you google Human Biological Adaptability. The data refers to Carl Bergmann and Joel Allen, 19^th century naturalists, who, through initially studying polar bears observed that the greater the bears’ body masses the colder their environment. Bergmann’s Rule indicates that like organisms living in the warmer regions around the equator have developmentally adapted to their environments, not genetically but biologically. Based on his study the polar bears eat massive amounts of food, creating massive amounts of heat, and effectively retain their internal heat.  Allen’s Rule, indicates the more body surface the faster body heat is lost. Based on his study of an East African Masai tribe below, having physically adapted to the extreme climatic heat by growing longer limbs to assist in heat loss.

                                                                  

            Other ways humans adapt to excessive heat is by sweating, evaporation of the body’s heat. It is our own cooling system. It is the body’s short term response to heat.

            A facultative adaption to heat stress would be a genetic change due to heat stress. As indicted above, perhaps the Masai tribe genetically changed through natural selection adapting a longer-limbed body, more surface area to evaporate more heat.

            Cultural adaption to heat is one of mankind’s greatest indulgences. Man has invented fans to swirl air around him and designed machines that create cold air to swirl around him. The buildings we live in provide a steady stream of moderate temperature at the flick of a switch or the turn of a dial. Unlike wearing fur to control the cold stress, clothing is often designed to be light and cool of the lightest weight materials in order to maintain a comfortable internal temperature. Diet is always trending one way or another from the heavy meals in the past to today’s fair, salads and lighter foods, the trend of today. The terminology “stick to your bones” refers to heavy meals of the past and the type of fair suited to a colder climate. The Masai diet consists of blood, milk, high fat meat and honey and tree bark. That could account for the difference in diet in their environments.

            Migratory patterns exist throughout the United States. The Northeast is a colder climate and the four distinct seasons affect the lifestyle, and results heartier humans who chose to live there. Much of the South and Southwest due to the influence of the natural heat gives rise to populations who prefer the heat. More specifically, since the late 1940s, you can see the migratory patterns of people moving from the Northeast coast down to Florida, due primarily to the intense seasonal changes in the North and a total turnaround in Florida.
            The benefit of studying humans across environmental clines is the categorization of the data. Compiling data is anthropology’s way of keeping track of mankind.