By Azriel ReShel / 06.30.2016
Colour vision in humans and why its important
Nothing delights the senses quite like colour. The iridescent blue of the waves on the ocean, the bursts of coloured flowers in a sea of green, or the breathtaking hues of sunset, affect our minds and our bodies. Colour enhances life and brings us great joy.
But, interestingly, humans weren’t always able to see the full colour spectrum, and while there are many creatures on earth who see ultra violet colours we humans cannot. So, what is our journey with colour and why is it important for our health and wellbeing? We need to turn to evolution for the answers.
Dr. Oscar Serrallach is an integrative health practitioner, who loves research and is fascinated by evolution. He enjoys being at the cutting edge of wellness medicine and has been intrigued by evolution since he was a young boy and would spend hours poring over his father’s scientific magazines. He has researched the evolutionary history of colour and believes it is vital for our health and wellbeing.
“Colour is a really enjoyable part of life. We find a lot of pleasure in colour and have a real sense of why colour is important,” Dr Serrallach explains.
Colour is vital for our health and wellbeing.
“There is a fascinating evolutionary story of colour which starts hundreds of millions of years ago when the first organisms with spines started to see light.”
“To see colour you need to have cones and rods. The more cones you have to differentiate different hues of colour, the more light sensitivity and colour sensitivity you’ll have. But you lose resolution and sharpness.”
Colour vision was an early part of evolution, and the first birds, reptiles, and bony fish all had excellent colour vision. Interestingly, the ancestors of modern mammals lost colour at the time of the dinosaurs, and some primates, including us, have re-evolved our colour vision.
“Animals had four coloured rods, then when mammals evolved they lost all colour vision, as mammals were originally nocturnal around the time of the dinosaurs. A lot of animals got two cones, called dichromatic vision, such as cats and dogs, who can’t see reds and greens. Then one day apes suddenly developed trichromatic vision, or the ability to see red, green and blue colour vision. Science is not sure when or how it happened. And around this time, a new colour, orange, also came out of it.”
When mammals evolved they lost all colour vision.
How do we see in colour?
Humans and some close relatives, have trichromatic – or red, green and blue – colour vision. Light is focused by the lens of the eye onto a layer of rod and cone cells. These cells of the retina contain visual pigments called opsins. There are three types of opsins in each rod cell and they are each sensitive to a different range of wavelengths of light, usually red, green and blue.
For most human beings, any colour can be reproduced by mixing together just three fixed wavelengths of light at certain intensities.
Trichromatic vision arises because the layer of nerve cells called the retina that capture light and transmit visual information to our brains use just three types of light-absorbing pigments for colour vision. Computer and television screens can mix red, green and blue pixels to generate what will be perceived by us as a full spectrum of colour.
Light is focused by the lens of the eye onto a layer of rod and cone cells.
Why do our eyes see in colour?
Initially all the research about why we see in trichromatic vision was focused on the ability and importance of seeing colourful pigments in foods but more recent research is showing other reasons we see in colour.
Neuroscientist and author of The Vision Revolution, Mark Changizi, says that the human eye evolved to see colours to detect what another person feels by noticing subtle colour changes in their skin. For example, when we blush, we flush red, we also become red-faced when angry or aroused. So, as social animals, we humans have optimised vision for sensing physiological changes in other human beings. The skin is altered by haemoglobin and this is only able to seen due to the presence of the light sensitive cone cells in the retina that detect colour.
“Humans are unlike any other animal, we have a huge amount of our brain set aside for social understanding and interaction, much more than any other ape. We have 33 facial muscles and no other mammal has remotely that. It’s all to do with subtle expression.” Dr Serrallach
This social nature is part of why humans survived and other apes didn’t.
“We have a much bigger part of the brain to recognise social cues and social analysis. Apes can only live in bands of 50 max, and they need direct social contact. Humans can relate with 150 – 200 and can have indirect social contact, because we are hardwired to gossip. So we can talk about other people without having to have physical contact with them.” Dr Serrallach
The other huge advantage of having colour vision is that we can see when fruit is ripe, and see red shoots that are higher in protein, which was advantageous in times of food shortage.
The human eye evolved to detect what another person feels by noticing subtle colour changes in their skin.
Colour in Food
Phytonutrients are the colourful pigments in food and they affect us by preventing disease and keeping the body working properly. In some plants phytonutrients include polyphenols, important micronutrients in our diet. Science is now proving these compounds have an important role in the prevention of degenerative disease such as cancer and cardiovascular illnesses.
“Polyphenolic compounds happen to have colour. So that’s a huge part of the evolutionary advantage. We can now actually see what’s good for us,” says Dr Serrallach.
The polyphenolic content of food is influenced by stress on the plant. When the plant is stressed, it produces these polyphenolic compounds to protect itself from things such as environmental degradation and insect attack or over grazing. Foods with high phenolic content are high in antioxidants and bioflavonoids. Goji berries, cacao, Kakadu plum all grow in high stress environments. As animals with colour vision, we can see which foods are good for us.
We can now actually see what’s good for us.
Why is colour important?
In The Color Cure, David Wolfe explains the connection between nutrition and colour. Different coloured food groups have certain healing properties for the body. Yellow foods are for the joints and support tissue building and tissue repair. We need to eat red foods for a healthy heart and blood building and enhancing the chi.
Green foods purify the system. They neutralise the body and are cleansing and detoxifying. Brown supports the intestine and digestive tract while blue foods help the thyroid and stem cells. Purple, a high spiritual colour protects the central nervous system and digestive system, and white foods are for the lungs. Black is about jing and the primordial life force energy. It supports bone marrow and the kidneys and with the jing connection, it is of course wonderful for longevity. So it may be time to enjoy a cup of coffee, which, by the way, Dr Serralach considers to be an amazing superfood.
“Coffee is one of the highest things in polyphenols, but when it’s produced poorly and the plant is not stressed properly, it is not a good thing. Caffeine is produced as a stress response by the plant and has great health benefits for us.”
So each time you decorate your plate with the colours of nature, you are truly providing medicine for your body. The more colourful the mandala on your plate, the more balanced your overall body health will be. Ever notice how at some times of the year, or seasons, you crave certain food? Well this is your body telling you what it needs. Eating seasonally will also support your physical needs, as the foods grown in your area seasonally, are perfect for the needs of your body, for example, oranges growing in winter time to supply us with more vitamin C as the temperature drops and we become susceptible to colds.
Interestingly, each colour has a biochemical shape. Clear and white to yellow are a simple shape. Orange, red, green blacks and violets and brown are more complex and blue is the most complex shape. And of course blue is the rarest colour found in nature and is not able to seen by some people.
Each time you decorate your plate with the colours of nature, you are truly providing medicine for your body.
The importance of language in seeing colour
“Language dictates to what degree we perceive colour.” Dr Serallach
He says the best example of this is the Himba people from the deserts of Namibia. “The Himba can’t see blue. They don’t have a word for blue. Interestingly, the ancient Greeks did not talk about blue, and Homer’s Odyssey talks about the wine deep sea.”
In recent research, scientists showed some of the Himba tribe a circle with 11 green squares and one blue square. The people couldn’t differentiate the blue square.
“They can’t find the blue square, but they have a whole variety of different greens. The brain hasn’t been trained to see the blue and for us, the different green hues are indistinguishable.”
The Inuits have a dozen words for the word white, as it’s really relevant in their world for them to be able to discern the different whites.
Dr Serralach says we choose our destiny in a lot of ways and that the idea of having “rose tinted glasses” is not that far off the truth in this case.
The Himba tribe couldn’t differentiate the blue square.
“The eye has a rod and three cones for every pixel and lots of the processing occurs in the back of the brain, so when they talk about rose tinted spectacles, the back of the brain definitely creates things and changes how we feel about things. The brain can even change things so that we can’t perceive different colours.”
The person with the highest reported visual acuity in the world was an Aboriginal girl from the northern territory. In her natural environment she would need to have acute vision to see the dangers of crocodiles, for example, and to find food.
So while we may have evolved as humans in so many ways, Dr Serrallach believes the knowledge of the ancients is the medicine of the future.
“We haven’t lost it, we’ve evolved in the forest, come onto the savannah and now we are living in high rises. Is that really good for us or not? We are locked in a two dimensional world. 3D is forest vision and it evolved in the forest. And its really important we go out and get that 3D magic back.”
The person with the highest reported visual acuity in the world was an Aboriginal girl.
He says that previously we saw vision mainly in 3D but that today we are this visual acuity is fading.
His solution to reclaiming our forest vision, is exercise and nature. We need to take our eyes for a 15 minute walk, as well as our legs. To go into a gym is a 2D world, this walk needs to be in the forest if we want to have natural 3D vision and not have to wear those crazy glasses.
The evolutionary story of colour is a salient reminder for our fast paced and ever changing modern lives. If we aren’t conscious and aware, we could lose more unique aspects of our functioning, and become increasingly one-dimensional beings due to the adaptations to living a mostly grey concrete, and digital modern life. It is important that we stay connected to nature, and to our colourful sources of food, as well as to each other, if we want to keep our brains and bodies functioning optimally.