Tag Archives: hair

About Melanin

(in case you’re wondering, the featured pic above is eye candy for my female viewers. Enjoy! LOL)

 

That fascinating molecule – no, group of molecules. So much more to melanin than I realised…

Melanin is the collective name for a group of pigments the body produces. Not just the human body, but almost all other animals* and even plants!

* Arachnids being among the very few exceptions. Hope you’re not arachnophobic!

In humans it’s abundant in the skin (where its main role is protecting against solar UV damage. This has been shown to have no effect on vitamin D production), hair, eyes & brain, and exists in four different forms:

BLACK EUMELANIN: Produced by melanocytes* in the stratum basale (bottom layer of the skin’s epidermis),

hair follicles,

and the middle layer of the eyeballs (uvea/ uveal tract), only a small part of which we see as the iris.

High quantities of it leads to extremely dark colouration. The name black eumelanin is a slight misnomer because if you look closely enough you realise no-one has literally black hair, skin or eyes. They’re just very very dark brown. If in low enough levels in the hair (but more than other pigments), it leads to silver hair.

The darkest human skin colour. Note how dark skin doesn’t always correlate with dark eyes…
… or dark hair

* Weirdly, melanocytes are also present in the bones, heart, inner ear and meninges (the membranes that cover the brain and spinal cord)! They have a common origin with nerve cells – the embryonic dorsal ectoderm – and as such look and behave similar to them. They have lots of branch-like outgrowths called dendrites that connect to other tissues, exactly as nerves have dendrites that connect to each other & to other tissues. They pass on melanosomes, melanin-filled vesicles, to other cells (eg. keratinocytes in the skin), exactly as nerve cells carry vesicles full of acetylcholine to each other.

 

 

BROWN EUMELANIN: Produced in the skin, hair and eyes along with the black form. This one is more obviously brown, though if in low concentrations in the hair (combined with low amounts of other pigments) it leads to blond hair! This may explain why a lot of people who were blond in youth turn brunette in later life; their brown eumelanin production has increased.

Naturally brunette east Asian girl

 

So, all albinos have white hair & pink eyes…

 

PHAEOMELANIN: also spelt pheomelanin, but I’m English so I use the British spelling. This one gives a pink-red-orange colour, which gives rise to red hair if it’s the predominant pigment there. In the skin it’s most concentrated in the nipples, lips and penis head/ vagina. I once heard that women usually have more in their skin overall than men regardless of ethnicity, but I don’t know how true that is. It’s true that red hair is most common among ‘white’ people, but…

SURPRISE!!!

They aren’t and never have been the only ones.

 

NEUROMELANIN: as the name suggests this form exists only in the brain. Interestingly, the levels of this we make are unrelated to how much of the other forms we make, hence even albinos produce normal amounts of it. Furthermore, humans are the ONLY animals that make so much; it’s much lower in primates & absent in all other animals! Scientists are still working out its functions, but so far it’s known low levels of it increase risk of Parkinson’s. It protects the nerves against free iron, lipids, pesticides & MPP+ (an unstable molecule that depletes ATP, cardiac adrenaline & dopamine, and increases cell death). It’s expressed in the adrenaline & dopamine-containing cells of the midbrain’s substantia nigra, contributing to its dark colour. It’s often claimed that it’s produced in the pineal gland but those claims might be confusing it with melatonin, a hormone that regulates sleep. The process by which neuromelanin is made is similar to the other forms but is turned into the neurotransmitter dopamine beforehand (probably explains why its levels are unrelated to eu & phaeo levels) and occurs much more slowly – years, as opposed to days/ weeks.

 

Melanin is ultimately made from the non-essential amino acid tyrosine, which is then oxidised (“burnt”, if you will) in different stages. The two eu & phaeo forms are what I’ll focus on most. If you’re more scientifically minded and want to see the production pathways, see the picture at the top of this post.

Note: in biology, a non-essential item means the body doesn’t need to get it from the diet. It makes enough by and for itself, eg. tyrosine, cholesterol, glycine, glutamine. 

There are other substances that contribute to colour, at least in the skin & eyes. That’s partially why we don’t get blonde or ginger eyes – unless we’re anime characters.

Very realistic anime character…

 

Eye colour is furthermore also determined by light; there is no gene that directly produces blue/ green eyes. They’re caused by a combination of congenitally low melanin and a phenomenon called Rayleigh scattering. That’s when light waves are scattered into their constituent wavelengths, most are absorbed into the pigments but the blue wavelengths are reflected back out, which is what we see. This is also what makes the sky look blue. Green, hazel & amber eyes are caused by that plus a higher ratio of phaeo:eu. This dependence on external light sources also means light eyes can turn different colours in different lights.

In case you’re curious, pink & red eyes have no melanin at all, the colour comes from the blood vessels inside the eyeballs. Violet eyes are caused by extremely low melanin, and is the rarest human eye colour.

Though I swear they look positively blue in other pics

 

 

 

 

 

 

In the skin, colour is not determined so much by how many melanocytes we have (since we all have pretty much the same amounts) but by their activity. They may produce loads or tiny amounts, and different ratios of eu:phaeo types. On top of that, there are melanin-inhibiting enzymes that can interrupt the tyrosine oxidisation process. Then there’s genetics, which is surprisingly simple as there are less than 6 alleles that account for skin colour. There are 50 different genes that control when and where melanin is deposited, which may explain why colour isn’t always uniform across the same tissue.

Piebaldism
Heterochromia of the eyes
Yes we can get freckles too
Mongolian blue spot

The master enzyme that gets the ball rolling with oxidation of tyrosine is tyrosinase. If that is knocked out the result is albinism. If it’s inhibited and/or releases melanin in an inactive form (as happens with a certain allelic switch) the result is fair/ light skin, which can be offset by long-term exposure to sunlight. Tanning, in other words. Apart from albinos, most people regardless of ethnic background are genetically able to produce enough tyrosinase to become very dark!

 

Now tell me they don’t wish they were us! LOL

Note that the reverse is also possible, that certain substances (including foods & food components) can decrease melanin production by inhibiting tyrosinase too! This may explain why when Buddha was in his ascetic phase, he claimed his skin was getting lighter beacuse of eating so little.

And apparently, the darker your skin the less vulnerable you are to hearing loss! WHAT?!?

So there you have it. Melanin is fascinating stuff, especially in the medical industry.

 

What’s all this fuss about natural hair?

Human hair naturally comes in different textures:

Afro-haired woman from Nossi-bé, Madagascar

Curly, also called coiled, spiralled or type 3. Though some like to think so, I don’t really think of afro hair (also called kinky, nappy, type 4 and less commonly crisped, woolly, fleecy, frizzy or crinkly) as separate from curly. To me it’s just the extreme end of curly so I refer to it as such, although it too can be divided into further gradations

Wavy, also called type 2. 

Straight, also called wiry, lank or type 1. 

This is partially because the follicles they grow from come in different shapes; curly & wavy hair grows from oval follicles, straight from circular ones. However, at least for some, hair naturally changes texture because the hair follicles change shape (though why this happens is unknown). It’s also partially because of the proteins in the hair strands themselves, which  are joined together by disulphide bonds. The more of these bonds, the curlier the strand.

Though type 4 hair is most common in indigenous Africans and their diasporic descendants, it is not exclusive to us nor is it the only texture we possess. As for type 1, it is most common in Easians but not exclusive to them nor is it their sole texture. Types 2 & 3 are pretty much the norm everywhere else.

Chinese girl exemplifying type 1 hair

 Hair also comes in different colours; black, brown (aka. brunette), orange (aka. ginger), yellow (aka. blond/e) and overlaps. This is because of different amounts of a group of pigments collectively called melanin, of which there are 3 types – black eumelanin (technically isn’t black but very dark brown), brown eumelanin (more obviously brown, like reddish/ chocolate) and phaeomelanin (yellowish-orange). Globally black is the most common hair colour, followed by brown, blond/e and ginger. White and grey hair can result either from old age (during which the hair typically produces less melanin of any kind) or from congenital lessened or aborted melanin production, such as the more extreme forms of albinism. 

 

So what’s all the fuss about? All people naturally have hair, right? Why should a post be made about it?

 

Well, here’s the deal. For ‘black’ people (especially women nowadays) it is often a self-esteem issue. Our story starts from the trans-Atlantic slave trade (TAST). When ‘white’ people captured Africans one of the first things they did was shave their hair. This may be no big deal to us but in some African belief systems the hair is on the head, and because the head is the highest part of the body it is therefore closest to God. This effectively meant that head hair was a symbol of connection to God. Therefore for the hair to be cut off and discarded like filth was, in a word, traumatising. 

However it gets worse. Soon after the slave trade started both ‘white’ and ‘black’ people were being worked like nobody’s business. However, while the elites started passing laws to stop them uniting and rising up they tried to find ways, no matter how trivial or fantastical, to justify the laws. They thus declared Africans to be naturally inferior and fit for eternal service, and one of the MANY ways they ‘evinced’ this was to pass judgments on the differences between Africans and Europeans. Nose shape, skin colour, language differences, lack of Christianity* and the like were all used (and this is also when the negative stereotypes started being invented), but for the purposes of this post we’ll focus on hair texture. The respected scientific minds of the time espoused that our natural hair texture was more bestial (beast-like), suited for jungle & wilderness and overall hideous and revolting. The church authorities agreed, claiming that our hair was part of the curse of Ham – even though the Bible doesn’t mention the nature of this curse.

* This was ignoring the newly converted slaves, and that Christianity came to Africa about 500 years before Europe.

As such, many ‘black’ people were convinced that their natural afro hair was cursed and ugly. They could have tried styling their hair, but as slaves they barely ever had the time and usually just covered it in a headwrap. The only way for them to have hair closer to ‘white’ people’s (what became known as “good hair”, a very common phrase in USA & the Caribbean) was to have children with a ‘white’ person. This meant that either:

1 – ‘Black’ men would have to have children with ‘white’ women (which as far as I know never happened back then. It would’ve been absolutely forbidden and the man could be killed/ mutilated for it), or,

2 – ‘Black’ women would have to have children with ‘white’ men (this was very common, and pretty much always happened without the women’s consent – in other words ‘white’ men raped ‘black’ women and their mulatta children, especially in the southern states of USA. And were never punished because raping ‘black’ women wasn’t considered a crime).

Almost ironically, the ones who worked indoors (who were usually the products of rape anyway and thus had “good hair”) were the ones who had the time to style.

Al Sharpton, ‘black’ man with straightened hair. Yes, even at that age

Even after the TAST was abolished and the Civil War had ended, the psychological damage therefrom was ignored. This damage has been passed down to near enough every member of the African diaspora since. The desire for straight hair gained strength and prominence in mainstream media since the 1900s, when it was considered a sign of prestige and changing from “country” life to city life.

 

Note: the desire for straightened hair infected the men’s and women’s minds.

This explains why so many subscribe to the belief in euro & mixed hair as good & afro as bad. Obviously not all of us believe it but we all are familiar with it, and most of us know why. The Black Pride movement of the 50s and 60s worked well to counter this damage – for the time being. However it didn’t last and the ‘white’ media pushed the image of straight hair as beautiful with a vengeance. This is why the vast majority of ‘black’ women now either straighten their hair* or wear weaves/ pieces. Funnily enough, ‘black’ men no longer do it (except Al Sharpton) but most of us have been brainwashed into preferring our women with long silky straight hair.

* To do this they can use hot combs, but the much more common – and more damaging – way is chemical straighteners. Some ‘black’ Americans call it creamy crack, because its use is compulsive despite the health problems often brought with it. See Chris Rock’s Good Hair for elucidation, as well as its psychological & financial effects on ‘black’ women. And ‘black’ men, even though most of us don’t use it.

Because of colonialism and globalisation, even many women on the African continent itself (especially in the industrialised areas where Western media flourishes) hide their natural hair texture under blatantly fake weaves. Luckily, natural afro hair is making a comeback throughout the African diaspora, through the sporting of African/ afro-hair-friendly hairstyles or not styling at all. Most ‘black’ women are somewhat scared to do this because they think afro hair doesn’t grow and therefore looks manly. Afro hair can grow to awesome lengths, you just have to know how to look after it.

Even short afro hair looks good and feminine

 

LONG natural hair

 However, there’s another phenomenon taking place. It’s highly counterproductive and I don’t know how prevalent it is so I’m not going to call it a trend, but there are cases of women with naturally non-afro hair (including ‘black’ women) getting it chemically treated to resemble afro hair! What the hell?

But anyway, long story short (tee-hee!), everyone should love their natural hair texture, ‘black’ women especially.

About blond hair in non-‘white’ people

Most people equate light hair with light skin but for Melanesians in the Pacific Islands, a.k.a. Oceania, this  isn’t the case at all as Melanesians typically have skin as dark as many Africans. I’ve known about the existence of ‘black’ people with naturally blond hair for quite a while. I also knew it was an indigenous trait not caused by early European explorers, as was previously assumed.

However, I had no idea about the genetics behind it. According to research by S. Myles, N.J. Timpson and others (geneticists) the blond hair trait has a different genetic origin in Melanesians than in North Europeans. In North Europeans it’s mainly caused by variants in a gene called melanocortin 1 receptor (MC1R), while for the Melanesians it’s predominantly produced by variation of a gene called tyrosinase related protein 1 (TYRP1). There were other genetic variants as well but this TYRP1 was the most prevalent among blond Melanesians, accounting for about 26% of hair colour variation*. In genetics it’s unusual for a single gene to account for such a high frequency of an observable trait. Just like in people of North European descent this gene variant is recessive so a person has to inherit it from both parents to have blond hair.

* With age and sex accounted for (as women and young children possess blond hair more frequently).

Some samples of blond-haired ‘black’ Oceanian children 

This variant of TYRP1 seems to occur only in Melanesians. This completely debunks an old hypothesis that Europeans brought the blond genes to that region when they first ‘discovered’ it in the late 16th century (when Spaniards were searching for the Ophir of biblical King Solomon, hence how the Solomon Islands were named). In the light of current scientific understanding, this hypothesis was flawed from the start since Spaniards never were well-known for having blond hair. After Melanesians NORTH Europeans (which doesn’t include Spaniards or Mediterraneans as they’re from South Europe) are known to have the highest frequency of blond hair on Earth.

This research was published in the journal Science, 4th May 2012. Here’s the link: http://www.sciencemag.org/content/336/6081/554.abstract

S. Myles, one of the researchers, made a telling comment about the current state of genetics and the implications of this research on it. He explained how in medical genomics research is done almost exclusively on people of European ancestry (i.e. ‘white’ people). This means most of the understanding of genetic disease risk comes from the smallest (and incidentally wealthiest) population on the planet. This inevitably ignores the vast majority of human genetic diversity and thus distracts from knowing of them. The comment can be seen at:

http://www.cultivatingdiversity.org/2012/05/03/melanesian-blond-hair-explained/

All very fascinating…