Melanin, and its two forms

Melanin is the pigment that gives skin, hair and eyes their colour, made by specialised cells called melanocytes. But "melanin" is really an umbrella term for two chemically distinct pigments produced along the same pathway:

Eumelanin is the brown-to-black pigment that dominates in darker hair and deeper skin tones. Pheomelanin is the red-to-yellow pigment concentrated in fair skin, freckles and red hair. Almost everyone makes both; what differs from person to person is how much of each, and in what ratio. That ratio is the quiet engine behind the entire spectrum of human skin and hair colour — and, as we'll see, behind how skin copes with the sun.

What actually determines skin colour

Here's a fact that surprises most people: the number of melanocytes is broadly similar across skin tones. Someone with very deep skin and someone with very fair skin have roughly the same count of pigment-producing cells. What differs is how much melanin those cells make, and crucially which type — the balance of eumelanin to pheomelanin.

That balance is set largely by genetics. The MC1R gene is a key switch: certain variants push melanocytes toward making more pheomelanin and less eumelanin, producing fair skin, freckles and red hair. Sun exposure then layers on top, stimulating more melanin production over time — which is what a tan is. Dermatologists often describe sun sensitivity using the Fitzpatrick scale (types I to VI), a practical shorthand for how readily a given skin type burns or tans.

How eumelanin and pheomelanin handle UV

This is where the two pigments diverge most sharply — and it's the heart of why skin colour and sun risk are linked. When a UV photon reaches the skin, eumelanin and pheomelanin do almost opposite things with that energy.

Eumelanin absorbs and dissipates it. Eumelanin is an efficient absorber of ultraviolet light. It soaks up the energy of incoming photons and converts most of it into harmless heat, while also physically scattering UV. This is genuine photoprotection — it's why eumelanin-rich skin burns less readily.

Pheomelanin does the opposite. Pheomelanin is a poor UV absorber, so it shields the skin far less. Worse, under UV it can act as a photosensitiser: it can contribute to reactive oxygen species formation under UV exposure, which may increase oxidative stress in the skin. In other words, pheomelanin doesn't just protect less; in fair, pheomelanin-rich skin it can add to the oxidative burden of sun exposure.

Why melanin is only partly protective

It's tempting to conclude that if eumelanin is photoprotective, then naturally pigmented skin is "covered." It isn't. Melanin is a real but partial and incomplete defence. Even the deepest skin tones carry only a modest amount of built-in protection — far less than a daily broad-spectrum sunscreen provides — and that protection does nothing to stop the cumulative UV exposure that drives photoageing and skin cancer.

This is the single most important takeaway of the whole topic: more melanin is not a substitute for sun protection. Deeper skin tones burn less easily, which can create a false sense of security, but UV is still reaching and damaging the skin. Every skin tone needs daily broad-spectrum sun protection — the difference in natural pigment changes how quickly skin burns, not whether sun damage accumulates.

Skin tone, sun sensitivity and skin cancer

The eumelanin-to-pheomelanin balance maps closely onto sun sensitivity. Fair skin with more pheomelanin — often Fitzpatrick types I and II, frequently with red hair and MC1R variants — burns quickly and carries a higher lifetime risk of UV-related skin damage. Richer, eumelanin-dominant skin tans more readily and burns less.

But "burns less" is not "immune." Skin cancer occurs across all skin tones, and in skin of colour it is often detected later and at a more advanced stage — partly because of the very assumption this article is trying to correct, that darker skin doesn't need protection or monitoring. The responsible message is the same for everyone: protect daily, and have any new, changing or unusual spots assessed by a dermatologist. This article is educational and isn't a substitute for that professional assessment.

What it means for your routine

Does Melanin Protect Against the Sun?

Partly — and the detail matters. Eumelanin, the brown-black form of melanin, absorbs and scatters ultraviolet light, giving naturally pigmented skin a degree of built-in protection and explaining why deeper skin tones burn less readily. But this natural protection is limited: it is far weaker than a daily sunscreen, and it does not prevent the cumulative UV exposure that causes photoageing and skin cancer. Pheomelanin, the red-yellow form, protects even less and can contribute to reactive oxygen species formation under UV. So melanin helps, but it is not enough on its own — every skin tone still needs daily broad-spectrum sun protection.

Why Do Redheads Burn Easily?

Red hair and fair, freckle-prone skin usually reflect a high proportion of pheomelanin and relatively little eumelanin, commonly linked to variants in the MC1R gene. Because pheomelanin is a poor UV shield — and can contribute to reactive oxygen species formation under sunlight rather than safely absorbing it — this combination burns quickly and is especially vulnerable to sun damage. For this skin type in particular, consistent daily sun protection and regular skin monitoring are strongly recommended.

Does Darker Skin Have More Melanin?

Yes — darker skin typically contains more total melanin, especially eumelanin, distributed in larger and more persistent melanosomes. Importantly, people across skin tones have a broadly similar number of melanocytes. The key difference is not the number of pigment-producing cells, but how much melanin they produce and what type of melanin dominates.

Can Melanin Prevent Skin Cancer?

Melanin helps reduce UV damage, especially eumelanin, but it does not fully prevent skin cancer. Natural pigmentation offers partial photoprotection, yet UV exposure can still cause cumulative DNA damage over time. This is why daily sun protection remains relevant across all skin tones, and why new or changing spots should be checked by a dermatologist.

Why Does Skin Tan?

A tan is the skin's protective response to ultraviolet exposure. UV stimulates melanocytes to increase melanin production, especially eumelanin, in an attempt to reduce further damage. While tanning reflects the skin's defence mechanism, it also indicates that UV-triggered stress has already occurred.

The Bottom Line: Melanin and Sun Protection

Skin colour comes down to two pigments — eumelanin and pheomelanin — and the balance between them, set largely by genetics, determines not only how skin looks but how it copes with the sun. Eumelanin is the more photoprotective form, absorbing and dissipating UV, while pheomelanin protects poorly and can contribute to reactive oxygen species formation under UV. This is the science behind why some skin tans and some only burns.

But the most important conclusion is the simplest. Melanin is a built-in defence that is only ever partial, and more melanin is not a substitute for sunscreen. Whatever your skin tone, the same rule applies: daily broad-spectrum sun protection, antioxidant support against free radicals, and regular skin checks. Melanin gives every one of us a head start — not a free pass.