Book One of the Trilogy
Melanin
The Science of Skin, Colour, and the Biology We Share
Fifty years of skincare and medicine have asked one classification to answer a question it was never built to answer. Melanin explains what that cost us, and what the biology actually says.
Inside the book
Thomas Fitzpatrick devised his scale in 1975 from a study of fair-skinned Australian volunteers, to solve one narrow clinical problem: calibrating ultraviolet-A dosing for patients receiving light therapy for psoriasis. It worked well for that. In 1988, Types V and VI were added to cover brown and black skin, but not from the same kind of data. They were added from assumption and appearance rather than from measured sun response.
Once Types I through VI were in circulation, the distinction between the calibrated part of the scale and the guessed part was forgotten. A six-point burn-and-tan classification became the default lens through which medicine, cosmetics and public health looked at every kind of skin on earth.
The book’s reframing is that skin is not one variable but many, largely independent of one another: pigmentation, oil production, barrier function, inflammatory reactivity, connective-tissue and scarring behaviour, pigmentary responsiveness, hair structure, microbiome and immune profile. A Fitzpatrick number tells you almost nothing about most of these. Two children of the same parents can inherit entirely different combinations, because each variable travels on its own genetics rather than riding along with visible pigmentation.
Built around six real family case studies, each one a variable the scale could not see, each grounded in peer-reviewed evidence.
The evidence
Darkly pigmented skin transmits roughly five times less UV to the dermis than fair skin: an intrinsic sun protection factor of around thirteen. That is real protection. It is not complete protection.
UK Biobank data put winter vitamin D deficiency at 17.5% in White European participants, against 38.5% in Black African participants and 57.2% in South Asian participants.
A 2025 multi-ancestry study of nearly eight thousand keloid cases found heritability of 34% in African-ancestry populations against 6% in European-ancestry populations. The risk is inherited independently of visible skin tone.
Core themes
Melanin and UV protection · Fitzpatrick scale limits · Hyperpigmentation · Vitamin D · Keloids · Reactive skin · Acne and eczema · Inclusive dermatology · Personalised skincare