FACTOID

      Some people have difficulty growing their hair beyond a certain length because they have a short active phase of growth. On the other hand, people with very long hair have a long active phase of growth. The hair on the arms, legs, eyelashes, and eyebrows has a very short active growth phase of about 30 to 45 days, which is why it is so much shorter than scalp hair. Transplanted hair doesn’t know it’s in a new location, so eyelash transplants from the scalp need to be trimmed every few weeks to avoid making you look like a tarantula.

      In addition to its utilitarian functions, hair reflects a lot about our self-esteem, taste, gender, age, and attitude. It also plays a major role in how we’re attracted to and attractive to other people (more on this in chapter 10). It can even be a source of conflict. While men tend to prefer women with long hair (ever see a painting of Eve with a buzz cut?), women, especially as they age, seem to prefer wearing shorter hair. More important, our hair tells us a ton about our overall health status, as the growth or loss of hair can signal other malfunctions going on inside our bodies. Whatever the case, we all know why in the United States alone we spend $50 billion a year^* on hair care: because we care about our hair.

      We care about cleaning it. We care about beautifying it. We care about keeping it in some places and losing it in others. Just as skin can shine and glow, so can your locks—as long as you use the right tactics to maintain your mane.

      Your Hair: Losing It and Abusing It

      In today’s world, we don’t treat our hair all that well. In fact, if your hair knew what was going on, it would be pulling its hair out.

      To show you how, let’s talk about the structure of hair—how it grows, how it can end up in your shower drain, and how it can end up looking about as lively and healthy as sun-scorched grass. The average person’s head has up to 150,000 hair follicles (the adult body has 5 million). That number is constant over a lifetime; it’s hereditary, so only thickness, condition, and whether you lose the actual strands that come from those follicles can change. Each one of those strands grows about six inches a year—women between the ages of 16 and 24 pump it out the fastest.

      Gone Today, Hair Tomorrow?

      If you lose a little grass in the yard, you just plant some new sod and let it grow. Seems like the perfect remedy, right? Well, that’s why many men have turned to hair replacement surgery as a way to deal with their male-pattern baldness. We have to say that we don’t think bald men need to hide their heads under hats or hairpieces. But many men do, and that’s why some have turned to this procedure in which hair is harvested from the back of the head and inserted in the front. These procedures have declined in popularity—not because the surgeries can’t be well done (they can be quite good if performed by a specialist, although nowadays many unqualified docs are getting in on the act). It’s because of genetics. After 20 years or so, the newly transplanted hair can thin as well—leaving very visible scarring. Isn’t a smooth, shiny scalp more attractive than one that looks like a connect-the-dots workbook?

      While it may seem that your hair is as far removed from your internal organs as your clothes or jewelry, each strand of hair has its own blood supply. Because of that, hair is greatly influenced by health and diet. Hair is also under the delicate control of hormones, which is why men have beards and hair on their chests and male-pattern baldness on their heads, and women don’t.^*

      As you can see in Figure 2.1, your hair is made up of distinct structures: the follicle and the shaft. A tunnel-like segment in the epidermis portion of your skin, the follicle resides under the surface of the skin and extends down into the dermis. The base of the follicle contains little blood vessels that nourish the cells. The living part is the bulb at the base, while the shaft—the part of the hair that we see above the skin—is dead.

      FACTOID

      It’s a myth that wearing a hat causes baldness. As long as the hat is not tight enough to restrict circulation (therefore cutting off circulation to the follicles), a hat will not cause hair loss.

      Figure 2.1 Hairy Situation While a hair follicle begins deep below the skin, what we do to the outside of hair can be criminal. Excess heat and other harsh treatments can make hair look frazzled, not dazzled.

      That hair shaft is made up of a protein called keratin. The inner layer (the medulla) and the middle layer (the cortex) make up the majority of the shaft. Like the nail’s structure, the hair’s cuticle, which looks like a tile roof under the microscope, serves as the outer, protective layer that covers the medulla and cortex.

      Now, to keep your hair shiny, it needs oil. Surrounding your hairs are tiny muscles that give you goose bumps, standing your hairs on end when you’re cold or during a scary movie. These muscles also squeeze the glands that lube up your hair, which produce sebum—your own natural vitamin E–rich hair and skin conditioner.

      Safari Secrets:

      Lessons from the animal kingdom

      Monkeys of certain species have patches of hair on their heads very similar to humans’; they develop during puberty and are found only among the males. In evolutionist language this is called epigamic hair, which means that it is a sign of sexual dominance. The lion’s mane is an example of epigamic hair, because it’s used as a scare technique during sexual fighting.

      How Hair Is Lost

      When it comes to hairy situations, many of us can live with a bad haircut or a little graying or the occasional day when our hair looks like a haystack. But the most frustrating problem for many people—men especially—is what’s perceived to be the start of the downhill slide to death, or at least the impetus for wanting that Corvette: hair loss.

      While we tend to say that baldness comes from the mother’s side, an individual’s genes from both parents influence that person’s predisposition to male-or female-pattern baldness. Of course, hair loss is far more visible in men (80 percent of whom experience some degree of baldness), but nearly 40 percent of women lose substantial amounts of hair after menopause, as well (women tend to thin out all over, rather than develop the signature spots that men do), making it a major appearance issue for both genders.

      FACTOID

      On average, you lose 50 to 200 hairs a day. Any guess as to when we have the most hair follicles? Bzzzz, try again. It’s when we’re in week 22 as a fetus; that’s the largest number we’ll ever have, since we don’t generate new follicles as we age.

      Underwear Under Hair

      As you may have noticed, pubic hair is quite different from hair on the head. Short, coarse, and curly, public hair never gets a chance to grow long because it has a short growth period. Within six months, the follicle dies and the hair falls out. Pubic hair—which acts as a buffer to reduce chafing and maybe to hide our genitals—provides a large surface area to disperse the naturally smelly sweat. Many animals use the odor of sweat from the groin and underarms (pheromones—see chapter 10 on sex and attraction) to attract the opposite gender. Today, it more often keeps people on the other side of the elevator.

      To learn how you lose hair, you first have to understand how it grows. Hair goes through its own growth cycle that’s unrelated to seasons or hormones or anything else. It’s a random biological process that’s dictated largely by your genetic disposition. The two main phases:

      Anagen (active): Cells in the root are dividing quickly and pushing the hair out. It averages two to three years.

      Telogen (resting): This phase lasts for about 100 days on the scalp. Consider it hair hibernation—the

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