Suppose you are telling your roommate that learned in Bio 322 that within any gi

Question

Suppose you are telling your roommate that learned in Bio 322 that within any given human population, height is highly heritable. Your roommate, who is studying nutrition, says, "That doesn't make sense, because just a few centuries ago most people were shorter than they are now, clearly because of diet. If most variation in human height is due to genes, how could diet make such a big difference?" Your roommate is obviously correct that poor diet can dramatically affect height. How do you explain this apparent paradox to your roommate? Consider skin color in humans. Does this trait show genetic variation? Phenotypic plasticity? Genotype by environment interaction? Give an example documenting each of your answers. Could phenotypic plasticity for skin color increase by natural selection in a human population? How?

Explanation / Answer

7. About 60 to 80% of the difference in height between individuals is determined by genes, whereas 20 to 40% of the difference is due to nutrition. Human height is a quantitative trait, and is controlled by multiple genes. However, height is affected by nutrition. The most important nutrient required to achieve final height is protein. Minerals, in particular calcium, and vitamin D and A also influence height.

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