What melanin is
Melanin is a family of pigments. In people it is made by cells called melanocytes, which package it into melanosomes and pass it on to the surrounding skin cells.
The main types
| Type | Colour | Where / role |
|---|---|---|
| Eumelanin | dark brown to black | the main photoprotective pigment in skin |
| Pheomelanin | yellow to red | concentrated in lips and hair |
| Neuromelanin | dark | found in parts of the brain |
Melanin is produced through a process called melanogenesis, which starts with the oxidation of the amino acid tyrosine.
Why skin tones differ
Humans have a similar concentration of melanocytes in their skin. Skin tones differ because of how much melanin those cells make and how it is distributed. Eumelanin is very good at what it does: it dissipates more than 99.9% of the UV radiation it absorbs.
The Fitzpatrick scale
Dermatologist Thomas B. Fitzpatrick created this classification in 1975 to estimate how skin responds to UV light.
| Type | Typical description |
|---|---|
| I | pale, always burns, never tans |
| II | light, usually burns, tans minimally |
| III | light beige, sometimes burns, tans uniformly |
| IV | light brown, burns minimally, tans well |
| V | brown, very rarely burns |
| VI | dark, deeply pigmented, never burns |
The scale is widely used but also criticised: it began with four categories focused on lighter skin, types V and VI were added later, and it does not capture the full range of skin colour.
- Melanin, Wikipedia
- Fitzpatrick scale, Wikipedia