We live in a world of black and white. For hundreds of years, human skin colour has been used as a marker of race. Now, science is uncovering the intricate relationship between skin colour and environment to reveal its crucial role in survival and reproduction. Skin colour tells a fascinating biological tale. When our ancient ancestors in equatorial Africa lost their body hair and ventured out into the open savannah, their skin had to become dark to resist strong UV radiation. Perfectly adapted to the environment, the black skin of Africans is one of nature’s greatest achievements for the survival of the human species. This may not sound new, but in 2000, Penn State University anthropologist Nina Jablonski proposed a startling new explanation as to why human skin has so many colours. Her study suggested that pigmentation did not evolve to prevent skin cancer, but primarily to help the human body maintain the right balance of two crucial vitamins essential for reproduction and body development. One is vitamin D, produced by skin reacting to sunlight. On the other hand, folic acid - a B vitamin that our bodies need to produce DNA and develop the neural system - can be destroyed by the sun’s UV rays. As a result, skin colour developed as a perfect compromise: allowing enough sunlight to stimulate the production of vitamin D, but screening the body from harmful rays that destroy folic acid. Skin colour is therefore more than just a suntan or a feature of ethnic origin - it is essential for survival and reproduction. Such findings pave the way for a long overdue reassessment of how we view skin colour. Today’s globalised world provides us with a further opportunity to look at skin colour from a new perspective. Skin colour has evolved in response to local environments over thousands – even millions - of years. But now, more than ever, people are moving around the globe to live in distant lands - and their skin pigmentation is not always suited to thei