Question: why are eyes different colours?

Hayley Evers-King answered on 20 Mar 2013:

Eye colour is not a very simple thing – there are lots of things in our genetics that determine what colour eyes we have. But there are some common patterns we can think about. People with light hair and light skin also tend to have lighter coloured eyes. In an evolutionary sense, these traits have been evolved to deal with living in low light, colder conditions – i.e. in the North. By constrast we tend to see darker hair, darker eyes and darker skin together – the pigments here protect the eyes and skin from damage from the sun. This is why people who’s ancestors have lived in hot places for a long time typically have these colour combinations. Obviously in the world today people and their ancestors have lived in lots of different places, so we see lots of mixes of these combinations.