In this cross-section of the skin on the human scalp, you can pick out hair follicles, hairs, sweat glands and sebaceous glands, among other points of interest. The follicle all the way on the left, with its resident hair, is easy to see.

© Visuals Unlimited/Corbis

Despite being as bald as a cue ball, I can grow a beard in a matter of days. Many men can't. Yet, they try hard, constantly growing hair and then shaving, believing their beards will grow thicker. It's a fool's errand. You see, I shave my head practically every day. If shaving made hair grow thicker, I'd have a full head of gleaming, streaming, flaxen, waxen hair by now and a beard like Santa Claus.

But I don't. Why not?

For one thing, hair growth is determined below the surface of the skin, in the dermis, where a tiny tube called a hair follicle is located. It's a little like the hole you might dig for a tiny seed before it starts growing above the soil. The follicle determines a hair's color, consistency and thickness. People have thicker beards, for example, because they have more hair follicles on their face. Genes, hormones and age all influence how many hair follicles a person has. Aside from transplanting some spare follicles from another part of your body, nothing you do can increase that amount [source: Shmerling].

Along with how much hair we have and where we have it, humans have been obsessing over the coarse matter of shaving for decades. A 1928 study published in the journal Anatomical Record concluded that shaving "a selected part of the beard area" has no effect on the color of a person's hair, its texture or growth. (Note: The study featured only four male participants, all of whom study author Mildred Trotter thanked heartily.) A 1970 study in the Journal of Investigative Dermatology confirmed that shaving does not alter "the width or rate of growth of individual hairs." That study featured five young men, all of whom were asked to shave one of their legs while keeping the other as a control.

Instead, shaving only gives the appearance of thicker hair. That's because a person's hair naturally tapers at the end. When you shave, all you're doing is mowing down the thin shaft and exposing the thicker part of the hair near the skin. While the resulting stubble might seem thicker, it's not. It looks fuller because the hair is cut straight and short. Moreover, that stubble may stand out against the normal color of your skin [source: Castro].

How did this myth about shaving and hair thickness get started? Like our follicle analogy before, it might be plant-related. That is, since pruning a plant stimulates the growth of new branches, maybe shaving does the same thing for hair. That's not the case though, as hair doesn't branch out like a rose bush. Each strand simply grows out of each follicle.

So why do men sport mountain man beards and 70s 'staches?