If one does any research and study of human size for an extended amount of time, one rule that will pop up over and over again is this eco-biological law that states that for a “broadly distributed genus, species of larger size are found in colder environments, and species of smaller size are found in warmer regions.” That law has been reworked to be applied for populations within a species. The varying measured unit is in terms of latitudes.
The Wikipedia article for Bergmann’s Rule can be found by clicking HERE.
From the Wikipedia article, “Bergmann’s rule is most often applied to mammals and birds which are endotherms, but some researchers have also found evidence for the rule in studies of ectothermic species. While Bergmann’s rule appears to hold true for most mammals and birds, there are exceptions.
…there seems to be a tendency for larger-bodied animals to conform more closely than smaller-bodied animals, at least up to certain latitudes, perhaps reflecting a reduced ability to avoid stressful environments by burrowing or other means. In addition to being a general pattern across space, Bergmann’s rule has been reported in populations over historical and evolutionary time when exposed to varying thermal regimes. Note that Bergmann’s rule describes a tendency of body mass variation within groups; it does not suggest that large-bodied animals do not occur in warm climates.
…the earliest explanation, given by Bergmann when originally formulating the rule, is that larger animals have a lower surface area to volume ratio than smaller animals, so they radiate less body heat per unit of mass, and therefore stay warmer in cold climates. Warmer climates impose the opposite problem: body heat generated by metabolism needs to be dissipated quickly rather than stored within. Thus, the higher surface area-to-volume ratio of smaller animals in hot and dry climates facilitates heat loss through the skin and helps cool the body. “”
Note: To get a better understanding of Bergmann’s Rule through a Physics Interpretation, click HERE for an explanation given by Palomar University.
Me: Here is my own interpretation of Bergmann’s Rule. There seems to be some credibility to the rule, just from an analysis of say the average heights of people in various countries.
There is a little over 200 countries in the world currently today. If we took each country, and managed to integrate the land area to find the medium latitude, or the horizontal line that can cut through the country, and graphed the average male and female heights in relation to the magnitude of the distance of the country middle point from the equator, we should find a weak correlation in the graph. Of course i am not going to spend 4 hours of my life actually going through the process to add and average and guesstimate at each individual country’s medium point just to proof my point that Bergmann’s rule has some validity.
Again, I have stated that the correlation is weak. It is absolutely true that there are a few rather tall ethnicities living in countries close to the eqautor and a few short ethnic groups living closer to the ice poles at the ends of the earth. As for the surface area to volume ratio theory, it seems to me like a theory forced through to justify a set of observations.
In science, there is two types of logic and reasoning. There is deductive, where one starts from theory and first principles and axioms, and try to use them to deduce results and observations from applying them on specific situations. The other is inductive, where one’s brain is basically a pattern recognition machine. If one notices two similar outcomes in two similar events, one’s mind will try to draw a trend line through the two data points and use that trend line becomes a theory or conjecture proposed by the observers to explain a set of phenomenon.
With Bergmann’s Rule, it is clear that inductive reasoning is used, and I would say rather forcefully. Living in the US, I am in contact with people of all different ethnicities. It is true that certain groups are on average taller than others (like Dutch to Vietnamese) so we could make a note of that, but I don’t want to use Bergmann’s Rule myself as a theory or tool to justify my own personal beliefs and viewpoints. It is just too weak to be used.