How many skin tones are there

Melanin levels are also determined by behaviours which influence exposure to the sun, because the body produces more melanin when it is exposed to the sun. An individual who works outside in the sun everyday will develop more darkly pigmented or tanned skin over time than they would if they worked indoors all day.

Melanin plays a vital role in protecting the body from UV radiation because it filters sunlight before it can damage skin cells. Sun exposure stimulates the body to produce more melanin to protect its skin cells. Individuals with darker skin originate from areas with high levels of ultraviolet radiation, close to the equator.

Book your health appointments online Find and instantly book your next health appointment with HealthEngine. Find health practitioners. Melanogenesis is the process through which cells called melanocytes produce melanin. These cells develop in the neural tube of the foetus, then migrate to the underlying layer of the skin the basal layer before birth. The process of melanin production is influenced by hormones, immune and inflammatory factors and brain signals. Melanocytes interact with other skin cells called keratinocytes which are responsible for storing melanin in cells called melanosomes.

It is stored for longer periods of time. In lighter skinned individuals melanin degradation occurs more quickly. The melanin which is produced is stored mainly in the upper layer of skin the squamous cells with very little melanin stored in the under layer of skin the basal layer. In determining skin colour, the number melanocytes of is not as important as the type of melanin the cells produce.

The number of melanin producing cells is similar between people of different ethnic groups. Hyper-pigmentation e. It is the process of melanin production and the manner in which melanosomes are transferred to and distributed within keratinocytes which changes skin colour. The size and quantity of melanosomes, also determines skin colour. Darkly pigmented skin is associated with larger and more prolific melanosomes.

They are elongated and the melanin they produce is stored in the keratinocytes for longer than it is stored in the keratinocytes of fair skinned individuals. In addition to melanin, other pigments including haemoglobin and carotene also help determine skin colour. Haemoglobin is a red pigment running along blood vessels. It results in skin being redder in places where the blood vessels come closer to the surface, for example the lips.

Eating excessive quantities of vegetables like carrots over a long period of time can change the skin colour. Excess amounts of carotene can result in accumulation in the skin, concentrated in tissues containing fat, for example the skin yellowing associated with jaundice from liver dysfunction. Exposure to the ultraviolet radiation from the sun causes changes to the skin colour. In the short term too much sun can result in what doctors called erythema and most people refer to as sunburn.

Artificial exposure to UV radiation, for example from a tanning bed has a similar effect. In the longer term UV exposure stimulates melanin production causing skin reddening to change to darker, tanned skin within a few days. Other UV induced skin changes include thickening of the outer layer of skin, freckles and moles and premature skin ageing, characterised by reduced elasticity, increased dryness and wrinkles.

Immediate skin changes immediate pigmentation , seen within minutes of sun exposure and lasting for minutes to several days, are induced by UVA radiation. They occur not because of increased melanin production but due to redistribution of melanin stored in keratinocytes in the upper layers of the skin.

Delayed pigmentation which occurs several days after exposure to sunlight and has a longer duration several weeks is induced mainly by UVB radiation. These changes occur due to increasing production of melanin, particularly eumelanin. Exposure to UV radiation from the sun and artificial sources like tanning beds is a major risk factor for all types of skin cancer melanoma, the rarest but most deadly type, basal cell carcinoma and squamous cell carcinoma.

The duration and intensity of sun exposure influences the type of skin cancer. Chronic sun exposure, for example being exposed to the sun everyday due to outdoor work, influences the melanin content of the skin; over time skin darkens. Chronic sun exposure does not appear to increase, and may offer protection from melanoma.

Intermittent, acute sun exposure is the major risk factor for melanoma, because over-exposure to sunlight causes cancerous DNA changes. Acute sun exposure refers to exposure for short periods of time in an individual whose skin is not usually exposed to the sun and is more likely to result in sunburn. This type of sun exposure occurs in office workers who spend a weekend or holiday at the beach.

Skin type influences the risk of cancer. Darker skin with more melanin is less likely to burn and skin cancer is rarely seen in darkly pigmented individuals, except on the non-pigmented skin of their bodies like the soles of their feet and palms of their hands. Fair skinned patients are more susceptible to the acute effects of sun exposure and have a relatively high risk of skin cancer. As skin cancer risk increases with cumulative lifetime exposure to UV radiation, age is also a risk factor.

Health Engine Patient Blog. Tools Med Glossary Tools. This delicate balancing act explains why the peoples that migrated to colder geographic zones with less sunlight developed lighter skin color. As people moved to areas farther from the equator with lower UV levels, natural selection favored lighter skin which allowed UV rays to penetrate and produce essential vitamin D.

The darker skin of peoples who lived closer to the equator was important in preventing folate deficiency. Measures of skin reflectance, a way to quantify skin color by measuring the amount of light it reflects, in people around the world support this idea.

While UV rays can cause skin cancer, because skin cancer usually affects people after they have had children, it likely had little effect on the evolution of skin color because evolution favors changes that improve reproductive success. There is also a third factor which affects skin color: coastal peoples who eat diets rich in seafood enjoy this alternate source of vitamin D.

That means that some Arctic peoples, such as native peoples of Alaska and Canada, can afford to remain dark-skinned even in low UV areas. In the summer they get high levels of UV rays reflected from the surface of snow and ice, and their dark skin protects them from this reflected light. Skip to main content. Chickens, chimpanzees, and you - what do they have in common?

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