You may already be aware of it, but if not, look at the men on the beach or at a pool. The men with obviously thinning hair, and certainly those that are bald, have more hair on their body, particularly the chest and back, than the men with full heads of hair. An anomaly, you may think. It’s not. Body hair and beard hair are stimulated and become longer and stronger by the action of androgens. Scalp hair, on the other hand, is quite the reverse when the genetic predisposition is such that the scalp hair follicles are more sensitive to circulating androgens.
It is odd, too, that bald men are thought to be more virile, but this is only because bald men are more hairy chested, and hairy bodies give the impression of extra masculinity. These have nothing to do with vitality. It is, of course, a myth perpetuated by balding men! Simply, it’s all a matter of hair follicle sensitivity.
Asian men – Japanese and Chinese in particular – who are least prone to baldness also have least hair on their chest. Tell them they aren’t as virile!
To reiterate then, male pattern hair loss depends upon two main factors: genetics and androgens (male hormones), which is why the medical name for it is androgenetic or androgenic alopecia – alopecia is hair loss and androgenic is androgens plus genetics. You can’t have male pattern baldness without androgens; for example, there has never been a recorded case of baldness in eunuchs castrated before puberty. The proportion of androgens produced, testosterone being the main one, although playing a part in the degree of loss, does not need to be excessive. In fact, normal amounts of androgens or even sub-normal amounts can cause hair loss in genetically predisposed men. The more sensitive the hair follicles are to the presence of androgens, the greater the effect of the androgens on them.
It is commonly thought that the gene or genes responsible for hair loss are passed through the mother’s family. This is not necessarily true: it can be from either side. Sometimes there is no discernable loss in any of the family, but a quirk or some predisposition from way back shows itself. However, whatever the origin, to develop male pattern hair loss you must have hair follicles that are androgen sensitive. You may think it’s a case of chicken or egg – it’s not really. Firstly comes the predisposition or ‘sensitivity’: without it, androgens won’t effect the follicles.