Human Variation and Race Blog

Body temperature in humans tends to fluctuate only in a narrow range about the value 98.6° F(37.0° C.). When the temperature rises above the normal range, corrective reflexes such as perspiration and reduced metabolism go into action to restore the steady state. In very cold climates, there is a constant danger of developing hypothermia, which is a life threatening drop in core body temperature to subnormal levels.  However, individual differences in metabolism , hormone levels, physical activity, and even the time of day can cause it to be as much as 1° F. (.6° C.) higher or lower in  individuals.  Hypothermia begins to occur when the core body temperature drops to 94° F. (34.4° C.).  Below 85° F. (29.4°C.), the body cools more rapidly because its natural temperature regulating system (in the hypothalamus  usually fails.  The now rapid decline in core body temperature is likely to result in death.

Our body’s reaction to heat loss is involuntary and driven by the hypothalamus, the tiny gland in the brain acting as a thermostat. Because of the stresses due to short-term adaptations, when a deviation goes beyond either the upper or the lower threshold, energy is mobilized to restore the steady state to its optimal value the biochemical and reflex defenses function adequately to protect some constancies.  Your teeth chatter, and your body shivers therefore producing a short-term warming effect. Faculty adaptations in cold would be the human physiological response to cold commonly including the evolution of more massive, compact bodies with relatively less surface area, increasing basal metabolic rate, fat insulation of vital organs, and change in blood flow patterns. Developmental adaptations to cold would be the cold favoring short round persons with short arms and legs, narrow noses and heavier than the average layer of body fat. These adaptations provide a minimum surface area in relation to body mass for minimum heat loss. Many people living in freezing climates drink alcohol to warm themselves.  This increases blood flow to the body extremities, thereby providing a feeling of warmth.  However, it results only in a temporary warming and can speed up the loss of heat from the vital internal organs, resulting in more rapid death from hypothermia.  A much more effective cultural response to extremely cold temperatures is the use of insulating clothing, houses, and fires.  People all over the world also adapt by limiting outdoor activities to warmer times of the day.  In some societies, sleeping in family groups with bodies pushed up against each other is also done in order to minimize heat loss during the cold months of the year.

The benefits of studying human variation from this perspective across environmental clines helps us to see how we humans can adapt to different kind of environmental stresses, and how our bodies react when exposed to all this certain pressures. It also gives us an idea of what our own limits are and how we all humans when exposed to these things have mange to survive under these circumstances. Information from explorations like this are useful to help us since we know are informed of what we could be exposed to for example when being in extreme cold and not being adapted to it you might certainly be on a risk for acquiring hypothermia.

To understand the variation of the adaptations I listed in #2 I don’t think there is a way I would use race since all kind of people could someday been exposed to this environmental stresses not counting the ones that are already accustomed and imposed to their usual environments. The study of environmental influences on adaptations is a better way to understand human variation than by the use of race because as I have already said everybody could have a chance to being exposed as in this case extreme cold weather no matter their race, environmental influences are different all around the world it is just a matter of being capable and flexible to adapt to it.