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! 

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Karma karma karma chameleon

Today I watched an epic documentary about reptiles & amphibians. 
While watching said documentary, absorbing all the glorious David Attenborough narrations, all of the unbelievably epic shots and marvelling at a whole bunch of cold-blooded creatures, I saw the panther chameleon. 

Edging along a branch through the Madagascan forest, I was captivated. It’s pincer-like hands gripped around the branch as it crawled along, it’s individually rotating eyes looking 360° around itself. It looked so perfectly adapted to its environment, I was in awe. 

And then I realised.

Chameleons are colourful. 

My blog is about colours. 

I can write all about chameleons! 

I’m sure this will surprise you all when I say I’ve never really known a lot about chameleons or any sort of reptile for that matter, so we’ll be starting with the basics. 

Chameleon

CHAMELEON

  • A chameleon is a type of lizard, part of the suborder Iguania
  • With 171 different chameleon species, the majority of them are found in Madagascar 
  • The largest chameleons are over half a metre long (69.5cm)
  • The smallest chameleons can be only 16mm
  • The chameleon will continuously grow throughout it’s life
  • Chameleons eat insects and birds with an absolutely crazy tongue that can shoot out twice as far as its body length
  • They are 1 of only a small number of animals that can change the colour of their skin

Now this is where it gets interesting. It’s a common assumption that chameleons can just change their colour to match their surroundings. Scientists believed they changed colour in the same way that octopus or squid do by adjusting pigments in their skin cells to alter colours. 

However, it doesn’t work quite like that. 

Chameleons change the colour of their chameleoncellskin in response to their emotions or environmental factors like light or temperature. More recent research has discovered they do it by changing the actual structure of their uppermost layer of skin cells called iridophores. 

These iridophores contain nano-crystals (made up of guanine, one of the key components of DNA) which will determine the colour of Chameleons skin. 
When these nano-crystals are all close together, the chameleon is in a relaxed state. Because of this closeness, only small wavelengths such as blue or green are reflected from the cells and that is the colour we see the chameleon as. (To read about different wavelengths of colours click here).

When a chameleon gets amped up, say if a rival comes along, the chameleon will stretch his skin. This spreads these nano-crystals apart from each other and will consequently reflect colours of longer wavelengths such as yellow, orange and red


Beneath this fascinating upper layer of cells is another, thicker layer of skin cells. Scientists believe it is this secondary layer of cells which help to maintain the temperature of the chameleon as the cells found here reflect near-infrared sunlight. 

However, all this cool skin cell stuff going on, only really happens in male chameleons. Female and babies are generally dull colours as they don’t need to be competing with rival chameleons therefore their upper layer of iridophores is greatly reduced in comparison.

To conclude one of my favourite blogs to write so far, chameleons are pretty amazing creatures. For more interesting info on chameleons check out these resources:

The Happiest 5km Run

Three years ago, I participated in the first Colour Run in New Zealand.

The proof follows.

927846_1380587055538581_1470963811_n

Also known as “The Happiest 5k”, you run/ walk/ skip/ jump/ crawl  your way around a track with periodically positioned stations of “colour” (powdered corn-starch) that gets thrown all over you. 

It truly is the happiest 5km run. You end up a walking rainbow, you’re not sweaty because you’re not really running, you’re rolling on the ground in coloured powder and you finish with a big smile on your face. Nothing could be better. 

So what were the reasons for creating such a fun run?

Apart from making some moolah of course, The Colour Runs – which are now found across the world from South America to United Arab Emirates – encourages people of any age and ability to be healthy AND happy. They even have a “Finish Festival” for everyone to dance it out and as stated on their website “release a few more endorphins”. 

You see, running or most workouts for that matter, encourage the release of endorphins. 

Endorphins = “any of a group of hormones secreted within the brain and nervous system and having a number of physiological functions. They are peptides which activate the body’s opiate receptors, causing an analgesic effect.” 

In other words… Endorphins are chemicals released from your brain which make you feel awesome, relaxed and take away pain. We like endorphins. 

endorphins

HAPPY ENDORPHINS

Endorphins are neurotransmitters. This means they actually move through gaps in between neurons (cells in your nervous system) and help deliver messages from one neuron to the next. 

They then join up to opioid receptors which are found all throughout your body but most notably in the nervous system along with endorphins. There are at least 17 opioid receptors and the best known 3 are mu, kappa & delta.

This joining of endorphins and opioid receptors can ultimately stop other nasty molecules (tachykinins) from being released.  A special type of tachykinin called substance P is in charge of transmitting pain and involved in inflammatory body reactions – not what you want being released. 

endorphinos

Some people may experience an endorphin rush from eating chocolate or even if they talk to a stranger. It’s letting you know you’ve had enough, but that you should definitely come back to it again, because it made you feel good. 

The same happens in runners, endorphins (mimicked by drugs like morphine and heroine) give you a rush of pleasure that helps ease the pain of those rubbing blisters, the aching muscles, your tired legs. After your run, you feel awesome, experience “runners high” and decide you want to go for another run tomorrow because it made you feel so good and accomplished. 

Endorphins are the bodies natural way of feeling high and euphoric without the need for drugs. Drugs do give off the same feelings, but also come with a whole lot of other issues and much more baggage. 

No wonder The Colour Run leaves people wanting more. 

  1. You’re exercising (encouraging the release of endorphins)
  2. You’re interacting with people, many of whom are strangers (also likely encouraging the release of endorphins)
  3. You’re most likely with friends or family who generally speaking should be making you feel happy anyway
  4. You’re surrounded by colour, and as we saw in my last 2 blogs (here and here), colours can make you feel pretty darn great!

 

Do you see what I see?

Hello, hello. Welcome back to my wonderful world of colour.

Or in this case, perhaps not?

I just took this test here.

Luckily for me, I am part of the 94.5% of New Zealand‘s population that doesn’t exhibit signs of colour blindness.
I am one of the lucky 259 women who can identify a blue hue from a purple one, the 260th woman might see them both as blue. For men, colour blindness is much more common with 1 in 12. 

And when I say luck, for the majority of cases, being colour blind is almost a luck of the draw.

You see, colour blindness is a genetic mutation passed down from your parents.
The affected gene is carried on the X chromosome.
Women carry two X chromosomes (XX).
Men carry one X and one Y chromosome (XY).

You get one sex chromosome from your mum (it’s going to be an X, that’s all she has).
You get your second sex chromosome from your dad (it could be X, making you a girl orrrr it could be Y, making you a boy). 

The genetic family tree below shows the potential offspring of a non colour blind female who carries the mutated gene on one of her X chromosomes AND a non colour blind male.

genepool.png

Both X chromosomes must carry the affected gene for a girl to be colour blind meaning her father MUST be colour blind.  Only having one affected X chromosome will result in that girl being a carrier and she may or may not pass on that X affected X chromosome to her own children. 

Colour blind men can only pass on affected X chromosomes to their daughters, as boys get their Y chromosome from their father. 

Naturally speaking, nobody can determine whether you will be a boy or a girl.
Nobody can determine whether you get your mum’s dud X gene carrying the colour-blindness genetic mutation or you get her other one.
So the way I see it, it all comes down to luck.

As I mentioned in my last blog, two clever guys by the names of Thomas Young and Hermann von Helmholtz came up with the trichromatic theory of vision involving colour receptors. You can read all about it here. 

cones

Our red, green & blue cone photoreceptors! 

At the back of the human eye, there are cone photoreceptors and rod photoreceptors. For the majority of cases, it is faults within the cone photoreceptor cells which lead to differences in the way a person might see colours.

Colours through normal vision (when all three cones are in good working order) generally look a little something like this….

colourblindew
However, have a browse through my table and have a look at how the different kinds of colour blindness affect the way in which these colours are seen. 

table

For people who are colour blind, some tasks in life can be made pretty tricky. This includes, but is not limited to, interpreting traffic light signals or coloured charts, or as simple a task as picking ripe fruit and veges at the supermarket. 

Unfortunately, there is no cure. However, it’s not all bad news. Modern technology advancements have contributed to helping out our colour blind pals. Apps have been created to help coordinate colours specifically for those trying to find an outfit that doesn’t clash. Some apps allow for a photo to be taken and all of the colours within that photo are then able to be identified with a simple tap of the finger. 

Also, technology in the optical world has now made colour-correcting glasses for people with red-green colour blindness that look exactly like any other pair of glasses. Which is pretty damn cool.

So next time you’re picking out those bananas at the supermarket and you can easily tell which ones are ripe and which are not, be grateful that you aren’t in that small, unlucky 5.5% of New Zealand’s population.