Ever wondered just what makes our hair curly? Why our hair springs out in twists while others’ flow in waves or straightness? Yes, genes are a big part of our hair-story, but I often questioned just what is in its biochemical make-up to make it act the way it does. Now that I’m in the natural-hair world, I decided that to better take care of my curls I need to get to the root of its structure. So time for me to geek out, don a lab coat and delve beneath the surface of our kinks and curls.
Back to Basics
Researching this subject has been be a little hairy (sorry) mainly because it gets so technical. I’ve simplified it all a bit as, like me, not all curly kellas will be versed in scientific jargon. So let’s start at the beginning and do a quick-fire look at the basic structure of hair.
The hair that is visible on our bodies; face, legs arms etc. is actually dead. Living hair exists below the skin’s surface.
It’s all Follicular
The hair follicle, a sac-like structure underneath the scalp, is the most important part of our hair, in fact the key determinant of what makes hair curly, straight, wavy, thick or thin. It holds one single strand of hair. To understand curls, we need to zoom in on the follicle’s three major structures:
1) The Dermal Papilla: Located at the very bottom of the follicle, it is made of connective tissue and blood vessels that nourish the germinal matrix or otherwise known as the hair matrix or simply matrix.
2) Germinal Matrix (Matrix): This is responsible for new-hair growth where cells produce new hair as old hair dies and falls out. These cells undergo a process of forming a layer of keratin- the protein that stops hair from falling out. They also add melanin to hair to give it colour.
3) The Bulb: The “living part of the hair that is fed by blood vessels and surrounds the Papilla and Germinal Matrix. It holds several types of stem cells and also contains hormones that affect hair growth and structure during different stages of life (puberty, pregnancy menopause).
There are more than two million hair follicles on the human body of which an average of 120,000 are on your head.
Other buzz words in curl chemistry are:
Sebaceous gland: When it comes to skin this little gland is the maligned culprit behind that colossal outbreak in spots. However in the context of hair it’s a whole other ball game. The sebaceous gland plays an important part in maintaining the health and moisture of our hair. Sebaceous glands lie below the surface of the skin in the dermis layer, where it meets with the hair follicle. Through this connection, the gland secretes sebum through the follicle and onto the surface of the skin.
Sebum is a waxy oily substance that comprises of lipids (fats). It lubricates the hair and acts as a barrier that regulates how much water is absorbed and retained through our skin. All those times you spend oiling your hair? Well it’s to mimic the sebum’s protective role in keeping our hair moisturised and strong.
Keratin: Ring a bell? It should do since it’s on every hair marketeers what’s-hot-list! Keratin treatments, products and supplements should be a clue as to what makes it such a big deal. Keratin is a strong fibrous protein rich in sulphur. It forms the building blocks of hair not to mention nails and skin. It protects the hair’s cuticle (the outer layer composed of overlapping cells – think fish scales or roof tiles) and inner core, the part that determines hair’s strength.
A healthy hair can stretch up to 30% of its length,…can hold a weight of 100g and an average head of hair twisted together can support 23 tons.*
Applying this to curls
Still with me? Right let’s see how these key words act in creating curly hair.
A big part of our hair is down to the shape and positioning of the hair follicle underneath our scalp. Check out the image below. A straight-haired follicle has a perfectly round shape, and grows vertically out of the scalp. Compare this to curly hair, the follicle is more elliptical and narrow, and is at an angle to the scalp.
Plus, below the surface the follicle is hook shaped which creates that signature kink to the hair shaft (see diagram underneath). The more hooked a follicle is, the curlier the hair. Both the follicle’s shape and its angled position in the scalp’s dermis make it harder for the sebaceous gland to secrete sebum all the way along the hair shaft. As mentioned, sebum lubricates hair, so this anatomical drawback explains the characteristic texture of curls: dryness.
Curly Hair takes some bonding…
At the crux of curl chemistry is the disulphide bond. While the follicular shape determines the curl, it is the disulphide bond that keeps the coiled shape intact.
To understand a disulphide bond, we need to take a closer look at the keratin protein. Keratin contains several copies of an amino acid called cysteine. Cysteine has sulphur-rich molecules that can bond with others only if given the opportunity to get close enough…which in a curly-haired follicle it does…a lot! These bonds are called disulphide bonds and are one of the strongest naturally-occurring bonds in nature.
So why does this all matter?
Sure the science may be a bit boring, but at the end of the day you want your curls to be the mane event. Now you know why curly hair requires a different cutting method and all round upkeep. Armed with this knowledge makes it more helpful when choosing the right kind of products to cultivate gorgeous healthy curls.
For example. Now that we know how curly hair is more prone to dryness due to the lack of sebum in the scalp, it makes no sense going with products that have alcohol in them as they will dry our curls even more! Remember: moisture is a curl mantra so look for brands that keep your hair hydrated. Certain oils serve your purpose (Vatika coconut hair oil is my favourite) and serums. Of course everyone’s hair is different, but once you have the basic building blocks of curl chemistry, you can make a smarter choice.
*Philip Kinglsey “Hair Biology & Bonds*