AllanBergmann Rule

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AllanBergmann rule




Different Yet Complimentary


Even though the Bergmann rule and Allan rule are different rules entirely they are both complementary to each other. In 1847 Bergmann observed that within the same spices of warm-blooded animals, populations have less bulky individuals are more often found in warm climates near the equator while, those with greater bulk, mass, are found further from the equator in colder regions. This is due to the fact that big animals generally have larger body masses that result in more heat being produced. The greater amount of heat results from there being more cells. A normal by product of metabolism in cells is heat production. Subsequently the more cells an animal has, the more internal heat it will produce. In addition, larger animals usually have smaller surface area relative to their body masses and therefore are comparatively, in efficient at radiating their body heat off into the surrounding environment. This is illustrated when the volume increases twice as fast as the surface size. Relatively less surface area results in relatively less heat being lost. In 1877, Allen went further than Bergmann in observing that the length of arms, legs, and other appendages also has an effect on the amount of heat lost to the surrounding environment. He noted that among warm-blooded animals, individuals in populations living further away from the equator in colder environments. This is due to the fact that a thin body with relatively long appendages is less compact and subsequently has more surface area. The greater the body area, the faster body heat will be lost to the environment. A tall and slender individual will have the same volume but greater surface area. It is comparable to an animal with arm and legs. I will demonstrate to you in this essay that even though the Allan rule and Bergmann rule are two different rules they are also complementary to each other. I will show this through explaining each on thoroughly, compare and contrast them and by presenting examples for each rule.

Carl Bergmann was a 19th century biologist who pointed out that amongst birds and mammal individuals of the same species tend to be larger and heavier when they lived in colder climates. This applies to pumas, bears, koalas, penguins, etc. Even in the case of people, there is an obvious difference between the height and weight of a high-latitude Scandinavian and those of an equatorial pygmy. The larger size increases the distance between the environment and the creature’s core, which has to be maintained near 37 degrees Celsius. The Bergmann rule is a scientific theory that states that the further from the equator, an animal needs a larger body with less relative surface area to help it stay warm in the winter. Conversely, smaller animals with a relatively larger surface area can dissipate body heat easier, helping them remain cool. The relationship between size and temperature was initially observed for endothermic animals and extended to insects, constituting Bergmann’s rule. The altitude and latitude, in which the insects develop, through the temperature, can influence their size.


Joel Asaph Allan, naturalist, born in Springfield, Massachusetts on July 19th 1838. He studied first at the Wibraham Academy, and then at the Lawrence Scientific School under Agassiz, where he devoted special attention to zoology, and was one of the assistants that accompanied Agassiz on the expedition to Brazil in 1865. He visited Florida in 1869, and the Rocky Mountain region in 1871, with the scientific exploring parties, and in 1873 was the chief of expedition sent out by the Northern Pacific railroad. In 1870 he became an assistant in ornithology at the museum of comparative zoology at Cambridge, and in 1871 received the Humbolt Scholarship. Since 1885 he has been curator of the department of mammals and birds in the American Museum Of Natural History, New York. In 1871 he was made a fellow of the American Academy Of Arts and Sciences, and in 1876 a fellow of the Natural Academy Of Sciences. He is also a member of the American Association For The Advancement Of Science, and of the American Philosophical Society. From 1883 to 1886 he was president of the American Ornithologists’ Union. He is the author of numerous reports and scientific papers among which are “On Geographical Variation In Color Among North And American Squirrels” (1874) to “History Of North American Pinnipeds, A Monograph Of The Walruses, Sea Lions, Sea Bears And Seals Of North America” (1880). Allen’s rule is a rule that states that among endotherms, populations of the same species living near the equator tend to have more protruding body parts and longer limbs than do populations farther away from the equator.


The Bergmann rule and Allan rule can be compared by demonstrating the information that these two rules come together as Bergmann and Allan came together to collaborate and find the following data. Adapting to a hot environment is as complex as adapting top a cold environment. However, cold adaptation is usually more difficult physiologically for human nature. We do not grow dense fur coats nor do we usually have thick layers of fat insulation like polar bears. The effect of heat on our bodies varies with the relative humidity of the air. High temperatures with high humidity makes it harder to lose excess body heat. This is due to the fact that when the moisture content of air goes up, it becomes increasingly more difficult for sweat to evaporate. The sweat stays on our skin and we feel clammy. As a result, we do not get the cooling effect of rapid evaporation, The dry hot weather humidity is low and sweat evaporates readily. As a result, we usually feel reasonably comfortable in deserts at temperatures that are unbearable in tropical rain forests. The higher the desert temperatures, the more significant of a cooling effect we get from evaporation. This relationship 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 Bergmann’s rule and Allen’s 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. Allan’s 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 lives, larger in body it will be. This is true because in the colder climates away from the equator, an animal needs a larger body with less relative surface area to help it stay warm in winter. Controversy, a smaller animal with a relatively larger surface area can dissipate body heat easier, helping them remain cool. Allen’s rule is a rule, which states that among endotherms, populations of the same species living near the equator tend to have more protruding body parts and longer limbs than do populations farther away from the equator.




Two examples of the Bergmann rule are House Sparrows and massive polar bear bodies. House Sparrows were introduced to North America in the late 19th century. Northerly animals are larger than the more southerly animals. This is consistent with Bergmann’s rule, which states the members of the same species in colder climates at higher latitudes will be larger. Polar bears have immense size with relatively small surface area from which they can lose their internally produced heat. This is an important asset in cold climates in addition, they have heavy fur and fat insulation that help retain body heat.




The two that demonstrate Allan’s rule are slender East Africans and Inuit man. This phenomenon can be observed among humans. The East African Masai men shown here are normally tall and have slender bodies with long limbs that assist in the loss of body. This is an optimal body shape in the hot tropical at a disadvantage in arctic regions. In such extremely cold environments, a stocky body with short appendages would be more efficient at maintaining body heat because it would have relatively less surface area compared to body mass.


Bergmann’s rule and Allan’s rule both are complementary to each other yet still being completely different rules. They have the same meaning and principles behind them. They show that things that are looked at as different can some times add and make each other more complete. Through there research it enables all of us to be able to have more of an understanding of why we are and look like who we do. Through this new understanding we can accept each other more fully. Through accepting each other for who they are on the inside there will be a lot less violence and a lot more peace in the world. “We are not enemies but friends we must not be enemies though passion may astray it must not break our bonds of affection the mystic cords of memories as again touch as they will be by the better of our nature” (America History X). This quote can be looked at two ways the first is the one that applies most to this paper that even though the concepts in the Allan-Bergmann rule has made us different we are still made up of the same kind of aspects. The second is by understanding these rules there will be less violence and this quote demonstrates why there should not be as much violence in the world today. Even though we are different we have to understand why we are so that we do not act on ignorance and hate or dislike someone because they do have these differences. It would have been just as easy if we were born at given place to have these same characteristics. Would the people who hate then hate themselves? I personally do not think so. In other words why do people hate when someone when they have a little choice about it as we do about our own given characteristics. Would those who hate want the same kind of treatment if we were born into this kind of place or this kind of family? It pretty much all goes back to the golden rule treat others how you want to be treated and those who hate would not want to be treated differently or hated if the they were the ones born into that kind of place or family. All these acts are just done out of pure ignorance of the Allan-Bergmann rules.




























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