The diversity of human colouring is the result of thousands of years of natural selection.
In prehistoric times, as the human population spread across the globe, the many and varied climates encountered meant that over generations the skin pigmentation, hair and eye colouring of each dispersed group began to adapt to their environment.
Cultural issues such as diet, clothing, shelter and health had an effect, but the major factor was the sun.
Dark skin provides protection from the sun and light skin synthesises more vitamin D when light is scarce.
The diversity of human pigmentation largely resulted from variations in ultraviolet radiation levels experienced by different groups of people.
In the context of human biology, pigment is the colour-forming chemical matter that makes each person’s colour characteristics unique. Pigment changes colouration.
Colour characteristics
Three pigments – or colour characteristics – affect the wide variety of human skin tones:
- Melanin.
- Carotene.
- Haemoglobin.
While there is still a great deal to be discovered about skin pigmentation, we know that the more melanin a person has the darker their skin will be.
The wide variety of colourations across the human population can be classified by combining the science of human genealogy and colour theory.
The individual characteristic colour adaptations which evolved over generations of living in the same local environment created groups of people with the same, or similar, colour characteristics.
The colouring of all three pigment characteristics was primarily determined by the consistency of weather conditions throughout the year.
Humans living close to the equator, where sun exposure is relatively intense all year (such as central Africa or northern Australia), developed high levels of melanin – resulting in warm dark pigmentation and low contrast across all three colour characteristics.
As people moved further away from the equator, in both south and north directions, they experienced partial de-pigmentation.
These areas where the sun was seasonal and the environment varied, included the tropics and the subtropics.
Different groups of people developed varied skin, hair and eye tones and diverse levels of contrast between their colour characteristics.
The people in the subtropics retained warm, dark brown hair and eye colour, but developed disparate levels of fair to light brown skin tones, with the ability to tan during summer seasons.
People who settled further from the equator experienced limited sun exposure and had less need for natural protection.
They developed lower levels of melanin, lighter skin, hair and eyes, and a reduced ability to tan.
From the various cool northern environments, cooler colour characteristics evolved, such as platinum blonde and ash-coloured hair, and green and blue-coloured eyes.
A new range of light, warm colour characteristics also evolved, such as strawberry blonde and red-based hair, pinkish skin tones and freckles.
Human migration and interbreeding between diverse groups created new dynamic colour combinations and characteristic contrasts.
Global migration
In modern times, accelerated global migration has seen unprecedented numbers of people travelling and settling across the world.
People are now living in areas where the sun’s radiation differs from where their ancestors’ skin, hair and eye colouring evolved.
This migration has resulted in an explosion of genetic diversity and mixed-race colour characteristics, and new generations have consequently developed unique combinations of colour characteristics and new colour expressions.
The difference between two people’s colour characteristics does not matter when they produce offspring – nature has the judicious ability to combine two individuals’ DNA and create a combination of colour characteristics that balance and harmonise.
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