Why doesn’t baldness affect all men in the same way?

Hippocrates, nearly 2500 years ago, noticed and commented on the fact that male-pattern baldness did not affect eunuchs. But it wasn’t until the 20th century that doctors identified the link between male-pattern baldness and dihydrotestosterone.
As we have seen, some men go bald because they are genetically disposed to do so. Their genetic make-up means that they produce more of a chemical called dihydrotestosterone, which weakens the hair follicles to the extent that they fall out and cannot grow back.
Many advances have been made in understanding male-pattern baldness and great steps forward have been made in isolating improved treatments. However, there are still many things that we don’t know. One simple question that scientists cannot answer, for example, is why armpits and beards remain unaffected. Why is it only our heads that go bald?
In the UK, 2/3rds of all men will succumb to male-pattern baldness. Altogether, that adds up to nearly seven and a half million individuals. Strangely, however, rates of baldness differ from race to race. While Caucasians and Afro-Caribbeans go bald the most, Chinese and Japanese men do bald much less. Male-pattern baldness, for some reason, does not occur at all among Native American men.
So there are still lots of questions to answer about male-pattern baldness. And who knows, maybe one day (if we study Native Americans enough) a cure will be found.