lationship between relative humidity light yellow range, life threatening heat stroke is likely. 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 warning and can spend 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 adept by limiting out door activities to warmer times of the day. In some societies, sleeping in groups is also practiced in order to minimize heat loss. When the environment is very cold, life can depend on the ability of our bodies to reduce heat loss and to increase internal heat production. As Bergmann and Allen observed, the human physiological response to cold commonly includes massive, compact bodies with relatively less surface area. Shivering can also be an effective warning technique. The increased muscle activity in shivering results in some heat production. There are three additional important types of biological responses to cold conditions found among humans around the world: increased basal metabolic rate, fat insulation of vital organs, change in blood flow patterns. Different populations usually develop at least one of these important adaptive responses to consistently cold conditions. The differences between these two rules can be seen in the definitions of Bergmanns rule and Allens rule. The Bergmann rule says that people in colder elements have bodies with a lower ratio of surface area to the volume to lessen the heat loss. Allans rule says that body appendages will be shorter in cold elements to reduce heat loss sending blood to the extremities. The Bergmann rule is a scientific theory that states that the further away from the equator an animal li...
