MadSci Network: Genetics

Re: Why are Asians generally short?

Date: Sun Apr 1 17:44:03 2001
Posted By: Paul Barrett, Staff, Science Demonstrator, Pacific Science Center
Area of science: Genetics
ID: 985313263.Ge

     The size and shape of an individual is determined by their genes, 
as well as by the environmental conditions that they have grown up 
in.  It is difficult to say whether environmental or genetic conditions 
are more responsible for the stature of many Asian populations.  
	    Different body sizes have different benefits associated with them. 
Bodies will adapt themselves to their environment in a number of 
ways.  People growing up in hot climates tend to have longer bodies 
and limbs to get rid of excess heat.  People in cold climates tend to 
have shorter broader bodies to hold in heat.  (Bergman's Rule and 
Allen's Rule).  Being smaller is, in general, more energy efficient, can 
make locomotion over different types of terrain easier (think of the 
mButi, or "pygmies", that live in dense forest in Central Africa) and a 
shorter height means less weight and a lower center of gravity, which 
means that injuries may be overall less likely to occur.  (Especially 
from bonking your head on things.) The height of Asians may be a 
product of what sizes were beneficial to their ancestors in 
environments that shaped them.
	    How large a person grows is also related to nutrition and health.  
In many underdeveloped  countries of the world, people do not get as 
much to eat and are subject to less sanitary conditions, without 
healthcare.  When people don't have plenty of food or are lacking 
certain key nutrients, they don't have the abundance of energy 
necessary to grow larger, especially when they are constantly fighting 
off sickness caused by living in unhealthy circumstances.  Over the 
last century, many Asian (and other) populations have gotten taller 
due to changes in their diets, especially when they eat more protein.  
But obviously not all Asians are living in impoverished 
	So in short, (so to speak) body size has to do with how an individual 
has adapted to different stresses (or lack thereof) in their 
environment, coupled with any  genetic predisposition for a particular 
body shape and size.  For a much more in depth look into this issue, 
check out this website:


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