Friday, 20 August 2010

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.

1. Hair shape

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)



2. Thickness of the cuticle layer

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

3. Number of cuticle layers 

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?

16 comments:

  1. I wonder if the hair shape differences mean anything.

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  2. I don't know - I got a very different feel from the data you've posted. More of, I didn't realise how much of a difference there actually was.
    I guess I shouldn't be surprised as the differences really explain the relative ease different races have in growing out their hair. Asian hair is seemingly impervious to damage compared to the relative vulnerability of afro hair.

    I once sat behind a group of chinese girls on a bus and noticed how incredibly thick and strong their individual hairs were in comparison to my fine ones - their's seemed 4 or 5 times thicker than mine and looked more like wire than actual hair. It was the first time I'd ever really looked at the individual strands of hair of another race and it was an eyeopener.

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  3. Dea not sure what data you are looking at but from what I posted all hair regardless of ethnicity has similar cuticle thickness and number of cuticle layers. The main difference is hair shape (for now.......until I post up the remaining data).

    I think that strand thickness varies between people of every race. I once did a Black lady's (Nigerian) hair and she had really super thick strands. I have seen White English girls with hair so fine you can nearly see the scalp (not thinning hair, just fine strands).

    I don't agree that Asian hair is impervious to damage, all hair gets damaged at some point. The main reason for the fragility of African hair really lies in the force applied during styling (combing mainly but also any other applied force like braiding or pulling when wet).

    Nonhlanhla Khumalo has done a lot of work towards investigating African hair and I think if you are looking for extra reading material then do go ahead and look her up.

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  4. Not surprised at all. I have come across this paper as well. We think there are differences because companies claim to formulate a special product for X and another for A, and of course because the textures look different.

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  5. I don't get it. You are saying no difference yet you posted several differences. Also, a blind man can see that there is a difference in the hair between the races. Keep in mind that I am searching for answers and not trying to be disrespectful as I am one of the Haven's biggest fans.

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  6. @ J Thomas: If I am not mistaken, hair shape differs from race to race (or person to person) due to the shape of the follicle that the hair grows out of. From my research our (people of African descent) can have follicle shapes that range from the oval shape to a star shape. This is why our hair is extremely kinky.

    No, I am not surprised at this for several reasons. Asians on average tend to have the coarsest hair type compared to any other race so therefore it is probable that they will have the most cuticle layers than anyone else, although I believe that my own hair is way coarser than most Asians. I would love to have my hair compared to theirs!

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  7. Looking forward to the rest JC - wondering if fine porous curly hair can use the same products regardless of ethnicity (I've read that red heads have the most coarse hair) (CHM)

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  8. Pebbles what exactly do you not get? The cuticle thickness is around 3 microns, the number of layers is about 7. Whenever a set of figures is presented the best way to look at them scientifically is for either the average or the median or the number that most repeats itself (i.e look if there is overlap). This is exactly why I am saying the hair is more similar than it is different. I guess I must be one of those blind men :)

    CHM - porosity in 'hairdressing' terms i.e space between the cuticles is not something that scientists research. Porosity in science means damage to the cuticle

    Msgg- This is true on the shape of the follicle. I remember posting up a small post last year about this. I will definitely check and see if any more work has been done on this.

    Ms-gg and CHM - question for both of you what exactly do you mean by coarse hair? I am not sure what physical property I would look at to find this.

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  9. coarse to me means thick (as in thickness of strand) (CHM)

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  10. I feel so at home with this post.
    It may be an obsession but I'm feeling scientific discussions about hair! *dork*
    :)

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  11. Jc - Great post! I am not surprised by the similarities, but it was still good to see the data broken down like that. Here's my question: when we talk about fine vs. thick hair are we referring to the diameter of the cortex? Does that vary based on race or is that individual?

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  12. Nope, not really surprised by the lack of difference at all. It's all human hair at the end of the day.

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  13. lol La Reine - Nerds are cool :)

    CHM and LittleOne - I will look for data on hair diameter. I think it will be difficult to estimate because the only round shape is Asian hair. For Caucasian and African hair, one side is bonund to be shorter than the other. Nonetheless, I will look :)

    Thanks all for the comments!

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  14. Update - I did find some data not on hair diameter but rather the area of the hair which is probably the best way to compare hair - will post it up later

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  15. Off topic post, but have you heard about tea and honey hair products?

    Marin

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  16. Quote:

    "Ms-gg and CHM - question for both of you what exactly do you mean by coarse hair? I am not sure what physical property I would look at to find this. "

    When I say "coarse" I mean the thickness of the hair strand. I know that hair that is coarse has an overabundance of protein in comparison to fine hair.

    Anyway, thank you for your knowledge JC you are the best :)

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