[intro] At least once in your life, you’ve probably
heard someone explain that if you start shaving somewhere new, the
hair will grow back even thicker. And if you’ve ever rubbed your hand across
some rough stubble after a recent shave, it’s easy to understand why. But as far as scientists can tell, this is
a total myth — even if our own experiences of battling body
hair seem to say otherwise. Scientists have been looking into the connection
between shaving and hair thickness since at least 1928, when a study had four men repeatedly shave
a certain part of their face. That experiment, along with other early shaving
studies, concluded that shaving didn’t make people more hairy. But they only measured the rate of hair growth,
and not the thickness of the individual hair shafts. So, in a later study from 1970, researchers
had 5 men shave one leg every week for several months. The other leg was left ungroomed, as the control. The team measured the diameter, density, and
weight of the hair, as well as the rate of growth, and concluded that shaving didn’t make the
hair grow back thicker. Other studies had similar results, like one from 2006 that analyzed high resolution
photos taken with a microscope. Overall, studies consistently find that shaving
doesn’t make hair grow back faster or thicker, or make new hairs grow in the shaved area. Still, the belief that shaving thickens hair
is remarkably common. Part of the reason might be that your first
shaving experiences often overlap with a dramatic period of hormonal
fluctuation in your life. If you began shaving regularly around puberty,
your hair probably was growing in thicker. But not because you were shaving! Another reason you might think the hair is
thicker when it grows back is that over time, hair gets lighter from exposure to things
like sunlight or chemical compounds. So the hair that grows back after a shave
can look darker, but your cells aren’t actually making hair with more pigment. Shaving also creates a bit of an illusion
around hair shaft thickness. When you shave, you’re not pulling the whole
hair shaft out of its follicle — you’re just slicing it off at the surface
of your skin. It’s like a blade of grass. When you let it grow naturally, it tapers
at the end, but when you pass over it with a lawnmower,
you chop it off near the base and leave a thick blunt end behind. The same thing happens with your hair. As it grows back after shaving, it feels thicker
and coarser because you’ve chopped it off at its thickest point, and lost the softer tapered end in the process. But as the hair continues to grow, wear and
tear will eventually taper off the blunt end again. So while you might feel some doubt as you
closely examine your stubble in the mirror a couple of days after your last shave, rest
assured: You’re not going to create a thick carpet
of hair through your grooming habits. Your body’s natural growth cycle is what’s
making that call for you! Thanks to Patreon patrons Allison and Gwendolyn
B for asking, and thanks to all of our patrons who suggest
fascinating questions for us to answer! If you want to help support this show and
get access to our patrons-only quick questions inbox, just check out patreon.com/scishow. [outro]
