After puberty, can certain diets, exercise, and/or possible drugs affect masculine/feminine dimorphism in adults? We know dimorphism and/or morphology is a product of genes, but to what extent can this be altered through environment? Like, can chewing more give a more masculine jaw shape/angle? Can talking a certain way make a more deep, manlier voice? Can squinting give hunter eyes?

For women, can eating soy-based products increase hip-to-waist ratio? Estradiol? Feminization of the face, cheeks and etc.? Likewise, in males, can vigorous exercise, drugs/diet and etc. masculinize?

Sexual dimorphism I mean as in how they look and what makes assure genetic/reproductive value.

Aside from genes, basically, what extent can diet, foods, exercise and etc. affect epigenetics, morphology and sexual dimorphism in animals, namely humans? Any evidence/studies/work on this?

This isn't intended to be a medical/personal question thing -- more so, broad on any means a human and/or animal may use their environment to try and improve dimorphism and morphology/phenotype.


There is a slight inaccuracy in your title question. Let's clarify to begin with:

I think you are asking whether environmental factors can affect sexually dimorphic traits. I don't think you are aiming to ask about dimorphism itself (i.e. the presence of apparent differences between the sexes) specifically. You're not interested in whether, say, food will affect sex dimorphism in humans but rather whether it can affect phenotypes which are sex-specific. It's a good correction to start with.

Can diet affect sexual dimorphism?

Of course. This is the case with all sexually dimorphic animals. A good example is nutritional deficiency, sub-optimal calorie intake or ingesting hormones or metabolically-active natural products from food. For instance, a male stag's antlers will not grow very much if the stag does not ingest enough phosphorus or calcium. This has drastic effects on its ability to reproduce, as often antlers are a key element in sexual selection in deer species.

Also, in some nutrient deficiencies, the body's ability to produce sex hormones is affected, which in turn affects secondary sexual characteristics such as jaw shape and the storage of fat. In bulimia and anorexia, periods become irregular due to the body's state of chronic starvation and inability to regulate menstruation with hormone cycles. Thirdly, diet can affect the ethology of disease (diabetes is a good example) which can indirectly affect sexual characteristics. There are many complex examples in which disease has an endocrinological (hormonal) component.

In addition, regular exercise, for instance, is well-demonstrated to affect testosterone levels.

It's important to keep in mind that not all traits which are sexually dimorphic are visible. For instance, smoking has an effect on sperm count, which is something not visible but still constitutes a sex-specific phenotype.

Can supplementation and drug-use affect sexual dimorphism?

Of course. I think taking steroids and hormones is an obvious example. I don't think this one needs explaining - a search engine can help here.

  • $\begingroup$ > Of course. I think taking steroids and hormones is an obvious example. < But I've seen people -- guys in particular -- who've used steroids and it didn't seem to affect dimorphism of the face. It builds more muscle, but doesn't necessarily create masculine dimorphism face-wise (i.e., stronger jaw; wider face; larger warrior skull; powerful brow ridge and etc.). If this was true then virtually every guy who's used steroids would look/have some kind of highly masculine, dimorphic, cro magnon-esque face, which we know doesn't happen to most male steroid users at least (but female maybe). $\endgroup$ – Frederick Benson Dec 20 '18 at 23:34
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    $\begingroup$ I don't think facial features are as 'plastic' in adulthood. Once they are set up, they change relatively little in shape compared to musculature, i.e. overall skeletal shape can't be changed much. The obvious changes that steroids induce are not skeletal, they are most obviously related to connective tissue, muscle, skin, fat storage, etc. Also, transgender individuals who have 'transitioned completely' with the help of sex hormones tend to have distinct facial features that are not typical of their biological sex. You can certainly masculinize or feminize faces artificially with hormones. $\endgroup$ – S Pr Dec 21 '18 at 11:25
  • $\begingroup$ Then wouldn't your point be rendered invalid then? If you're a man with bad, non-dimorphic male bone structure and hormones do not make a difference in this way, how would they affect dimorphism then? A non-dimorphic face is bound by bones primarily. How would fat/skin/etc. matter if the overall structure of the hard tissue is what appears non-masculine? In fact you agree yourself with the "distinct facial features that are not typical of their biological sex" part you mentioned. It seems hormone manipulation post-puberty barely affects dimorphism. $\endgroup$ – Frederick Benson Jan 16 at 4:40
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    $\begingroup$ You're using the word dimorphic incorrectly. I wouldn't use terms like bad either, it's not clear what you mean. I don't think you appreciate the diversity of things taking place when you introduce steroids. If a man takes estrogen, he will grow soft tissues on his breast region. Breasts are not typical male characteristics. If a woman takes testosterone, she will find an increase in muscle mass, changes in fat storage and a deeper voice. Muscle tone or body shape are very typical indicators of sex-specific traits. Your last statement that hormones barely affect dimorphism is thus incorrect. $\endgroup$ – S Pr Jan 16 at 13:39

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