A friend told me one afternoon, and he presented it as a “trivia fact,” that women are on average shorter than men, because males on average prefer, and always have preferred, shorter females to taller ones. He argued that females were not shorter than males originally, but through a process of natural selection, determined by the males’ selection of mates, these “female shorter” genes were reproduced, and caused women to now be shorter than men. I decided to do some research.
Apparently, Darwin himself had coined the term “sexual selection.” Males and females choose their mates according to certain characteristics. Whoever has the most desired characteristics gets to reproduce. As a consequence, only certain characteristics get to be inherited by the future generations. For example, any trait that allowed males to beat potential competition for their selected female mate, became one of these most inherited characteristics. This might explain why taller men seem to have been preferred by natural selection. However, we still don’t have an explanation for the shorter women.
Stephen Sterns, professor of evolutionary biology at Yale University claims that shorter women statistically seem to bear more children. The data came from the Framingham Heart Study, a 1968 study which lasted 60 years. The survey had about 5,000 subjects. Another study by Open University’s Daniel Nettle found that shorter women are more likely to be in long term relationship and have children. He explains this by claiming that shorter women reach puberty before taller women, and that could explain why males chose shorter women over taller ones in the past.
Finally, the University of Helsinki found an actual gene that could further explain our quandary. This gene is involved in cartilage development and it effects height, making individuals shorter. Most importantly, it acts more strongly in women than in men. This gene is present in the X chromosome. One of the X chromosomes in females is usually inactive and potentially silences the genes it carries. However, this particular gene seems to be able to remain active. Therefore, females either presented the gene on one chromosome, or in some cases in both. The latter scenario would explain why it acts more intensely in females.
All summed up we found out that my friend was right. Preference in sexual mates had to do with it. However, it was not all up to the males’ preference. Males are taller because larger males could more easily defeat possible competitors. We also discovered that a gene might actually be involved, and that shorter women have more children and therefore spread their “short genes” more!
JacquelineFilmStudent 
Very interesting post! For most animals, including primates, females are the sex that chooses a mate, while males compete with each other in order to gain access to a mate. How do you think this system could have influenced sexual dimorphism (like height) in humans?
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Oh interesting.. I think my article is wrong then! Everything I read didn’t mention that in primates, or more specifically hominids females choose their mates! That would change everything I wrote. Wouldn’t it?
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Sorry I meant “Nothing I read mentioned anything about females choosing the mates” not “Everything I read didn’t mention” …. Grammar!!
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That is an interesting subject. I’ve never seemed to wonder why girls are shorter in general. It is crazy to think that height is also connected with how our genes are expressed and inherited to make up our physical appearance.
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Right? I never thought about it either untill a friend mentioned it to me, and told me there was a scientific explanation and I was like whaaat? Haha
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