[A brief intro: My wife likes to ask me questions about anything and everything that pops into her head. I don't mind; she's pretty good about me staring at her with a confused look and no answer in sight. I'lluse this forum as an outlet on attempting to come up with a decent answer for her. And if anyone else has any questions they'd enjoy watching me fumble around on for a few paragraphs, feel free to drop a comment. --G]
You always complain about how much I shed. Why does the hair on some people's heads fall out more often than other people's, but they are not going bald?
Before answering this one, let me give the readers a quick overview of my living condition. I cohabitate with one black cat, one shaggy mutt, and one long-haired wife. It seems as if there is a constant struggle to keep stray hairs off of the bathroom sink and out of the kitchen. I'm constantly finding long dark hairs on my clothing and have recently begun finding them at work attached to my lab coat.
So the question is, where does she keep coming up with new hairs without going bald, and how can we somehow package this and sell it to 40-something execs in sports cars?
On average, the human head contains between 120,000 to 150,000 hairs growing from follicles -- pockets of cells designed to grow individual hairs. This process, like many in the body, takes place in the form of a cycle. First, the hair grows and divides within the follicle, in a process very similar to mitosis. Next, a cellular signal is given and the hair stops being made, and the root is pushed closer to the tissue surface. This is where the hair will fall out. However, the bulb still remains connected to its original location via a series of small nerves and will return to grow another hair in the course of a few months. This cycle can take anywhere from months to years depending on the location, care, and other environmental factors. For instance, eyebrows only take 3-4 months to complete a cycle, whereas it can take scalp hair 3-4 years.
The matter close at hand is it seems like the more hair you have, the more you will lose. Obviously, the longer it is, the more noticeable it is. People lose, on average, around 100 strands of hair a day. Why you don't go bald from it is another issue.
Baldness, or alopecia, isn't well understood. One factor may involve slowing of the hair's growth stage, leading to normal hair loss without rigorous replenishment. This is a reason why chemotherapy leads to hair loss. Cancer drugs keep cells from dividing, and this includes the production of new hair. In addition, the male androgen hormones (testosterone) seem to deplenish hair growth, while female hormones such as estrogen are protectants. Thus, when women have low estrogen levels postpartum or postmenopause, extreme hair loss can occur, similar to male-pattern baldness.
So basically, losing hair is normal. I should just get over it. Interestingly, in my research I found a few theories on why baldness happens in evolutionary terms. Apparently, in gorillas, a large forehead is considered a sign of maturity. The apes with the largest foreheads were seen as the most attractive. Others claim that's it's just a normal process of going from hairy ape to naked man.
So don't despair, balding men. Blame your ancient ancestors.
