Like intelligence, height is genetically determined, however there are thousands of genes implicated in height determination. That is why the finding 1 by researchers from Harvard Medical School of a gene variant responsible for shortening the average height of Peruvians in about 2.2 centimetres is so interesting.
There are other rare gene variants known that cause much greater decreases to medium height but their impact on the population is small. People homozygous (carrying two copies) for this new variant, however, are 4.4 cm shorter than the average of those not carrying it. That is probably why Peruvians are some of the shortest people in the world, with average heights ranging from 159 to 165 cm in men and women, respectively.
A FBN1 gene variant responsible for up to 4 cm height decrease
This variant affect the fibrillin-1 (FBN1) gene, which produces a protein part of bone, skin and other tissues. Even though some mutations in these genes lead to Marfan syndrome, in the 5% of Peruvians showing this variant there are no signs of disease.
As curious as this finding is, there are yet no explanations as to why this variant was selected in Peruvians, but if someone would ask me, I’d say that probably the geography of the country could have helped natural selection. And the data seems to agree with my hypothesis, just not as I thought. Since the researchers found the gene variant more commonly present in the Peruvians living on the coast than in the Andes or the Amazonas, my idea that it might be an adaptation to mountain heights doesn’t fit any more.