There's no doubt that male hormones (androgens) somehow cause hair loss in those with the genetic predisposition towards it. Furthermore, dihydrotestosterone (DHT) is the androgen directly linked to this process.

However, genetics and male hormones do not fully explain the exact mechanism that will cause hair loss to start. That's because they can't answer the following questions:

Q1. Why do some people lose hair from the front (receding temples), the back (a bald patch), or both these regions of the scalp?

Q2. Why is it that hair can fall faster in one region of the scalp than it does in the other, and start at different times in a person's life? (E.g., about 20% of men start losing their hair at puberty but most don't start until they're much older).

Q3. How can DHT be linked to both hair loss and hair growth? (DHT will, during puberty, stimulate hair to grow in other parts of the body).

These are all very relevant questions about the hair loss process. So, it's important that complete and accurate answers are given before any theory can be acknowledged as the true underlying cause of androgenetic alopecia.

It now seems more likely that the actual mechanism that causes this type of hair loss is Skull Expansion. Here's a very brief explanation of how this process causes genetic hair loss:

When you're growing up into an adult, your skeleton obviously gets bigger and bigger. This, of course, includes the skull, which not only grows in size but also changes shape.

Once you reach adulthood, this process (called bone remodelling and resorption) then continues throughout life. For some, this simply involves maintenance of the bones (i.e., keeping them strong and healthy). But, for those who suffer hair loss, this process will cause the frontal and parietal bones of the skull to grow.

This is Skull Expansion, and is the direct cause of hair loss within the male pattern baldness (MPB) region of the scalp.

The genetic link to male pattern baldness is due to the skull shape you inherit. Different skull shapes will have different growth potential (this simply means that the predisposition towards Skull Expansion will vary). The extent to which you lose hair is directly related to the extent to which your skull will expand. Obviously this means that greater Skull Expansion will cause more hair loss.

Only Skull Expansion can provide answers to all of those earlier questions:

A1. Hair loss at the front is caused by Skull Expansion of the frontal bone. A bald patch at the back is caused by Skull Expansion of the parietal bones. And hair loss at the front and back of the scalp simultaneously, is caused by Skull Expansion of both frontal and parietal bones.

A2. The different rates of hair loss between the front and back of the scalp depend upon the skull shape you inherit and its growth potential. That's why your hair loss could start as early as puberty or much later on in life.

A3. DHT can stimulate hair growth, but it also encourages bone growth. Androgens like DHT are steroid hormones which have an anabolic effect on bone formation (i.e., they make it grow!) DHT causes Skull Expansion, which then causes hair loss to start.

So, now you know that the true cause of genetic hair loss is Skull Expansion. And, should you be in any doubt, why not simply contact a hair specialist, ask those questions, and see what answers you get!