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People in different countries have different average heights. For example, Wikipedia's article on human height states that Australian men have an average height of 177.8 cm, and Australian women 163.8 cm, whereas Japanese men have an average height of 170.7 cm, and Japanese women 158 cm.

Are these differences in height due to environmental differences between people in different countries, or does genetic differences play a role?

In particular, are Asian people (people from Far East countries like Japan) genetically predisposed to be on average shorter than people who are of European descent?

米凯乐
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Andrew Grimm
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1 Answers1

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Note: This is too long for a comment, so I will post it as an answer, even though it is merely an example and not a full answer to your question.

An example of the environmental influence on human body height can be found in the statistics assembled by the Swedish conscription service from 1840s to 2010 (when general conscription ended). During this time the average height of Swedish men (aged between 18-21) increased from 167.4 cm (in 1841-45) to 180.2 (in 2004), an increase of 12.8 cm or 7.6% (Werner 2008, unfortunately in Swedish, but tables 2 and 3 should be understandable). Here is a graph of the data found in the paper:

Height of Swedish men at conscription

During this time Sweden has gone from what would have been a bottom-20 position in the wikipedia list of average human heights (close to contemporary India or Mexico) to a top-10 position. This is clearly not due to changes in the genetics of the population, but to changes in the environment (probably mainly due to nutrition). I know that many countries have gone through a similar development, and this is usually refered to as a secular change or trend in body height and weight (see e.g. Roche, 1979 and Loesch et al., 2000 for further examples).

Nothing of this naturally contradicts that genetics is a powerful determinant of human height. However, it shows that the average height in two countries cannot be compared in a meaningful way (at least if you want to infer genetic differences) without knowing something about the nutrition status and the average living conditions in both countries. The situation is rather that genetics is setting the limits of potential height, but that environmental factors will determine the actual outcome. This is also discussed in the paper above, but there are certainly better references to be found in English. In the reference list (#9, #10) you can also find examples of how there are also well-known genetic determinants of e.g. short stature in some human populations (in this case decreased insulin-like growth factor I receptor expression and function in African Pygmys, see ref #10)

fileunderwater
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  • Why is it clear that the height change in Swedish men is not due to genetics? – canadianer Jun 15 '14 at 23:33
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    @canadianer Because we don't expect such dramatic changes to happen in frequencies of gene alleles in a human population of that size given the shortness of the period, absence of severe bottlenecks or strong directed selection and polygenic nature of the trait. – alephreish Jun 16 '14 at 16:46
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    See @har-wradim answer. Remember that 150 years is only a couple of human generations, and this drastic change is would require an extremely strong selection pressure. For the most part, this increase in height is caused by the shift from a poor mostly agricultural population to an industrialised, well-fare nation. Also remember that a similar shift has been observed in many industrial countries. – fileunderwater Jun 16 '14 at 18:08
  • This also doesn't disprove that there is a correlation between genetics and height, it only proves that there are other factors besides genetics. For this, we should analyze a group of Japanese living at least since the second generation in a Western country. – vsz Dec 07 '14 at 14:04
  • @vsz Agree, and this is also what I'm saying in the last paragraph. – fileunderwater Dec 07 '14 at 19:31