This image is not directly related but it made me wonder if there was a relationship between the nature of the hair follicle and baldness, namely that the follicle cannot 'hold' the continuously growing hair, and it constantly falls out in. I wonder if this is the case or if the hair literally just does not grow out from the follicle at all.
I'm no expert on the whole matter, but I know that at least when it comes to male pattern baldness, it is caused by a hormone called dihydrotestosterone. As those men with the right (or wrong genes, however you choose to look at it) age, this hormone causes the hairs to progressively lighten and thin up until the hair stops growing altogether. The hair follicle dies out basically.