Ethnicity and Hair: It doesn't matter if your are Black or White (or Asian!)

There is still an ongoing debate about whether a product can work on a Black person if it has been tested on White hair. I have often dismissed this argument because the fundamental structure of hair is not based on race but rather from the fact that we are all of the human species.



However, I realise that I have spent a lot of time reading through papers and so my understanding comes from compiling this information together in my head. It makes no sense to keep it in my head only! I decided to collate the information and place it here for all to see, discuss and critique.




A lot of praise goes to Nonhlanhla Khumalo, a South African scientist who spent time and effort studying and comparing African hair to Caucasian (mostly) and Asian hair. This segment today is all about the physical structure of hair.

It is agreed that depending on race the shape of the hair strand when cut in cross-section varies (Dermatologic Therapy, Volume 17, Number 2, J pp. 164-176(13), 2004)











Several scientists have examined the cuticle in detail. In this section I am referring to the total cuticle layer thickness meaning how much cuticle surrounds your hair?







The table below lists the measurements taken from hair near the scalp (i.e where the cuticle is thickest).  A micron is one thousandth of a millimetre, just incase you didn't know just how thin this layer is.

	African Hair	Asian Hair	Caucasian Hair
Thickness of Cuticle Layer (total)	~2.5-3 microns	~3 microns ~4 microns	~2 microns ~3 microns

Sources

 Experimental Dermatology, 14: 311–314, 2005

 J. Soc. Cosmet. Chem., 22, 839-850, 1971, 

International Journal of Dermatology, 45, 1435–1437, 2006







I have previously mentioned that each cuticle layer is actually made up of several individual layers. Here is an old diagram to illustrate this.


So in section 2 above, the total cuticle layer was found to be approximately 3 microns. This section asks, how many layers occupy this distance of 3 microns?

	African Hair	Asian Hair	Caucasian Hair
Number of  Cuticle Layers	7*	7 7-10	5 7-8

* Note: The study gave a measure of 3-7 for African Hair. This range was based on measuring the cuticle layers from root to tip. I was interested in the root section only (where the cuticle is thickest) and therefore assumed that the highest number belongs here.



Sources:

Experimental Dermatology, 14: 311–314, 2005

Journal of the Society of Cosmetic Chemists, pg 155-75, 1978

J. Soc. Cosmet. Chem., 22, 839-850, 1971

International Journal of Dermatology2006,45, 1435–1437




Coming up next 

1. Protein structure

2. Hair growth rates

3. Hair strength



What do you think so far? Are you surprised by the fact that we are are alike? Or are you not surprised at all?