What makes curly hair happen? Learn how genes, follicle shape, hair bulbs and hydrogren and disulfide bonds create curls in the hair so you can treat it properly.
Merida’s curly locks in the award-winning movie “Brave” were nothing short of a miracle. In fact, it took six Pixar research engineers and artists three years to bring the locks to the big screen. Curly hair is hard to pin down, literally and figuratively, but the more you know about the science of your hair, the more properly you can treat it.
How hair grows out of your scalp determines whether it’s straight, wavy, curly or kinky. The shape of the follicle, located underneath the scalp, plays a large part in the amount of curl created. The hair shaft is what you see when the hair grows out of your follicle—a flexible protein called keratin made of three parts: the medulla, cortex and the cuticle.
Now that we’ve covered some basic anatomy, we can dive into what makes curly hair curly or straight hair straight.
Genes- Curls are hereditary and curly hair is a dominant trait. If your parents have curly hair (even if one parent does), you’ll end up with either curly or wavy hair.
Follicle Shape- The shape of your hair follicle largely determines your curl. Oval follicle shapes produce curly hair while round follicles produce straight hair. A flat oval shape will create kinky, coily hair.
To help you visualize, think of a piece of gift-wrapping ribbon. In order to curl it, you need to flatten out one side with a scissors. When you do this, you’re transforming one side of the ribbon while keeping the other side the same. It’s this difference in shape—when one side is curved but the other side is flat—that makes your hair curl.
Hair Bulb- The hair bulb is a pear shaped structure located at the base of the hair follicle. For those with curly hair, the bulb is slightly hooked. Straight-haired people have little to no hook on the bulb.
Disulfide Bonds- Located in the cortex of your hair strand, disulfide bonds occur when sulfur atoms in the keratin protein form bonds of two or more. These bonds are permanent and can only change when hair undergoes a texturizing (in other words, a perm) or relaxing treatment.
Hydrogen Bonds- These temporary bonds are what make your hair curl up on a humid day. They change every time your hair gets wet and dries. These are also the bonds that you manipulate when you use heat styling tools like curling irons or straighteners. Since humid air has more water molecules than dry air, your hair forms more hydrogen bonds, thus turning your perfectly straightened hair back into a heap of curls!
Curly hair is vulnerable, the twists and turns in the structure make the cuticle weaker and also increase the amount of tangles. An exposed cuticle makes the hair more prone to damage, so make sure to use a heat protectant when you’re doing any type of heat styling. As far as tangles go, if you need to brush you hair be sure to do it when it’s wet. Dry curly hair is very hard to brush. If it’s your only option, approach it with caution, or try finger combing through the strands to try and minimize frizz as much as possible.
Scalp oils have a harder time coating the entire hair strand; so curly haired folk don’t have to worry as much about greasy hair. However, they do have to worry about dryness in the scalp and hair. Try a sugar scrub to get rid of dandruff and use tea tree oil to soothe. A hot oil treatment or medicated shampoo and conditioner will also moisturize and smooth the strands.
The science doesn’t stop there! Curly hair’s unique coiling properties were recently studied to aid industrial manufacturers in understanding the natural curvature of flexible rods like steel pipes. However, the study also yielded results that researchers hoped would be useful for animators hoping to give more diverse hair types to their characters in their films.
So be “Brave” and don’t hide it! Embrace your curly hair! Using the right curl products and understanding how your hair works is a great way to keep your locks healthy and in control. Stay curly, my friends.