" Race is one millimeter deep. Intrepidly attending the dissection of a corpse", Bryson quotes the surgeon who pulled back a minute layer of skin and said: “That’s all that race is – a sliver of epidermis.” As we spread across the world, some people are thought to have evolved lighter skin in order to glean vitamin D from weaker sunlight. Throughout human history, people have “de-pigmented” and “re-pigmented” to suit their environment.

Biologically, skin colour is just “a reaction to sunlight”, Bryson quotes the anthropologist Nina Jablonski as saying. She adds: “And yet look how many people have been enslaved or hated or lynched or deprived of fundamental rights through history because of the colour of their skin. "

― Bill Bryson , The Body: A Guide for Occupants