Rhonda M. Davis - Published October 7, 2021
Hair. Its been with us since birth. Whether you have an abundance or wish for more, we all share similar hair dilemmas over the years.
Each of us has various hair types. Whether its straight, fine, curly, wavy or coily, there is a scientific reason why your hair takes on its texture.
For starters, our hair fiber consists of the protein keratin. According to the National Institute of Health (NIH), each hair follicle is anchored into the skin and a hair bulb forms the base of the hair follicle. Now that we understand that, let’s get into the nitty gritty. Per the NIH, in each hair bulb are living cells that divide and grow to build the hair shaft. To maintain these living cells, blood vessels within our skin deliver the necessary nutrients for hair growth and structure.
Within this hair bulb lies the medulla, located in the center of the hair fiber. This medulla layer is surrounded by another layer called the cortex, which makes up the majority of the hair fiber mass and is comprised of keratin and lipid proteins.
It doesn’t stop there. The outermost layer is called the cuticle and this is what we touch and feel on a daily basis. Per the NIH, this outer cuticle is comprised of dead, flat overlapping cells in a scale-like formation, forming a protective layer around the inner layers of the hair. While dead, the cuticle protects against environmental, oxidative and styling stressors we encounter each day.
So why do we have varying hair types/textures? Well, you might want to sit down for this one. Remember the cortex? While we now understand that it makes up the majority of the hair, it contains multiple sections as well! According to the NIH via Mercer (1953), the cortical cells are divided into different regions termed the orthocortex, paracortex and mesocortex. Per Kajiura (2006), the distribution of the cortical cells determines the curvature of the hair fiber.
Straight hair has an even, symmetrical distribution of the ortho and paracortices. Curly hair on the other hand has an uneven, non-symmerical distribution of these cortical cells.
So remember:
Straight Hair = Even, Symmetrical
Curly Hair = Uneven, Non-Symmetrical
Can you scientifically alter these cortical cells? At the moment, no.
Genetics is always at play but there are various ways to manipulate the hair to your liking. Click here for our vegan, plant based options for curly, wavy and straight styles.