The Colours of People

Everywhere you look, there are people. Different sizes, different shapes, different colours. And that’s pretty awesome.

But why do I have green eyes, my mum has blue and my dad has hazel?
Why is my hair a shade of browny blonde but my sisters is almost black?
And why oh why do I have to roast myself in the sun to get any form of tan that some people just have naturally??

 

greeneyes


All of the colour differences between people stems from pigments – any substance found within our cells which colours us in some sort of way.

It is the special kind of pigment, melanin which is to blame for any of your 3 major body colourings: eyes, hair & skin. 

Melanin

Melanin is made within melanosomes which are found in cells called melanocytes.

Three important types of melanin include:

  1. Eumelanin = dark pigment 
  2. Phaeomelanin = light pigment 
  3. Neuromelanin = responsible for colouring regions of the brain – problems with neuromelanins are linked to Alzheimers and Parkinsons diseases.

The amount of these types of melanin we each get is determined genetically.

 

Melanindiagram

Eyes

In our eyes, the melanin is found in the iris (the coloured part surrounding the pupil). The top layer of the iris is called the stroma and this is where those melanocytes are found.

Eyediagram

More melanin will result in dark brown or black eyes. With over 55% of the world rocking them, brown eyes are the most popular eye colour.
Less melanin means blue, green or hazel eyes. Green eyes are the rarest in the world with approximately only 2% of the worlds population having them. 

Skin

In our skin, those melanocytes are commonly found in our deepest layer of skin, the basal layer. There are many factors which determine skin colour and it comes down to the size, distribution, shape and number of melanosomes plus how active the melanin within them is. It also takes into account the gene protein melanocortin 1 receptor (MC1R).

redheadMore MC1R activity = more eumelanin, less phaeomelanin. 

Some people have sort-of faulty MC1R genes and they are likely to have red hair, pale skin and freckles. 

Very simply, if you have high amounts of eumelanin but low amounts of phaeomelanin, the resulting skin will be black or brown. If you have low amounts of eumelanin but high amounts of phaeomelanin, the resulting skin will be light (freckles are likely too). People with very little levels (or none at all) of both eumelanin & phaeomelanin will have extremely light skin, this is known as albinism.

What about tanning? The more you expose skin to ultra-violet (UV) rays from the sun, the more melanin the skin produces. This will result in darkening the skin and helps to protect skin from any more damage. sun
Back in the day when most people huddled around the equator, they got a whole lot of sunlight and therefore a whole lot of vitamin D too (from the UV radiation).
We need vitamin D to help prevent illness such as rickets or soft bones so when people started moving away from the sun and dispersing to different, darker parts of the world, their bodies began to compensate for this loss of sunlight and the resulting loss of vitamin D. This happened by lower levels of melanin being produced and the lightening of skin, so more sunlight would be able to be absorbed. 

Hair

When it comes to hair, I barely know whether to describe mine as brown, blonde, muddy blonde, light brown? Sometimes I see strands of red and sometimes strands of black? It’s a bit of an identity crisis situation. 

You see, just like out skin, hair contains eumelanin (dark pigment) and phaeomelanin (light pigment). The density and the dispersal of the different types of melanin and their pigments will also contribute to differing hair colours, which can also happen across the space of one head. 

There is brown eumelanin and black eumelanin. 
If only a small amount of brown eumelanin is present, the resulting hair colour is blonde. Larger amounts of eumelanin will produce brown, dark brown and black hair. 
For red-heads, phaeomelanin is the dominant pigment which people with dark hair also sometimes produce. However, the darkness of their hair, thanks to eumelanin, overpowers the light pigment. In my case where I see hair strands that are red, light brown, and blonde, it is likely due to some phaeomelanin being produced. Grey hair is when only a small amount of melanin remains in the hair while white hair is the complete absence of melanin.

hair

There are so many variables in our hair, skin and eye colours and that makes a pretty cool world full of unique and interesting humans. We’ve heard it before, but really, if we all looked the same, the world would be a pretty boring place! 

Advertisements