Why do Men go Bald?

July 4, 2015 / Humans / 0 Comments /
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This is something you may have wondered about, but equally may not have, because male baldness is something which is so common in society that it often isn’t spared a thought. But really, it is odd. Just like only having thick hair on our heads, male baldness is something which is quite unique to humans, yet rarely thought about (well, until you start to go bald perhaps). So here, I will explain why baldness occurs, and why it only happens in men.


Hair growth cycle

It is first important to understand the growth cycle of hair, which can be split into 3 phases:

  1. Anagen phase (growth) – This is simply where the hair is growing.
  2. Catagen phase – During this phase the hair follicle stops growing (and effectively starts dying).
  3. Telogen phase During this phase a new hair follicle replaces the old one, which is shed, and the cycle begins again.

Studies on human hair has shown that 80-90% of hair is in the anagen phase (i.e is growing), 1-2% is in catagen phase (i.e not growing) and 1-20% in in telogen phase (i.e undergoing replacement with a new follicle)1.


Causes of Hair loss

There is no one cause for hair loss, and even more frustrating, there is still much unknown about this phenomenon. However, there are a number of areas which do play a role in hair loss.


Poor nutrition (and even over nutrition) have been linked to hair loss. One particularly important nutrient is zinc, and it has been noted that when a zinc deficiency is restored, skin and hair growth improve too. Chances are, unless you live quite a healthy diet full of unprocessed plants and animals, you will be deficient in zinc to some extent, although this doesn’t mean it is the cause of baldness.

A deficiency of vitamin D, which again, is commonly lacking in many Western societies, is also associated with hair loss. However, the link between vitamin D and hair loss isn’t very well understood, and more research is certainly needed.

Although there is little doubt in my mind that nutrition does play some role in baldness, it doesn’t explain why women don’t go bald, and hair loss only strikes males in their 50’s (unless they are seriously under nourished, then it can strike at any age). There is clearly more to this than nutrition.


Hormones have strong link with hair loss, and it is a good explanation of why men go bald, and women don’t.

The hair follicles are particularly sensitive to a male hormone called DHT, which shortens anagen phase (growth phase) of the hair, and makes the hair follicle much smaller. Over time, this could damage the follicle and prevent hair production, and this is thought to be the cause for 50% of hair loss amongst men.This is quite a unique feature of male humans, and isn’t even shared amongst other primates.

Other hormones are also linked to hair loss, such as the thyroid hormones, which in dogs has been shown to cause hair loss in 25% of the sufferers, and could have similar effects in humans. Problems with the thyroid gland are not uncommon, and so may be a slight contributor to hair loss.

GeneticsBaldness is inherited from the mother's genes. I

Genetics seem to play the biggest role in the cause of baldness in men, interestingly, it seems to be genes which are inherited on the mother’s side. This means the best way to predict baldness would be to see if/ when your maternal Grandfather went bald, and see if your Mother’s brothers went bald. If they all went bald at a young age, it doesn’t look good for you.

Although there will be a number of genetic factors involved, one of the key genetic factors thought to cause baldness in men is the how the hormones and receptors are distributed in the hair follicles.


Summary – why do men go bald

Although scientists admit that there is still much to learn about the mechanics of baldness, the causes seem to be relatively well understood.

The primary cause for baldness seems to be genetics, which influence hormone production and hormone receptors is the hair follicles. These hormones are thought to cause about 50% of male baldness, and possibly more. As these hormones are exclusive to males, only males will go bald this way.

The cause for the remaining 50% of baldness cases is not so clear, and may be a combination of nutritional, lifestyle, infectious, other genetic factors or other hormones factors such as thyroid hormones.


Wiedemeyeer K, Schill WB, LOser C Skinmed. 2004 Jul-Aug; 3(4):209-14.

Images courtesy of Edson Chilundo and Neil Moralee