We are surrounded by stories of people on the move. Wild species, too, are escaping warming seas and desiccated lands in a mass exodus. Politicians and the media present this upheaval of migration patterns as unprecedented, blaming it for the spread of disease and conflict, and spreading anxiety across the world as a result. But the science and history of migration in animals, plants, and humans tell a different story. Far from being a disruptive behaviour, migration is an ancient and lifesaving response to environmental change, a biological imperative as necessary as breathing. Climate changes triggered the first human migrations out of Africa. Falling sea levels allowed our passage across the Bering Sea. Unhampered by borders, migration allowed our ancestors to people the planet, into the highest reaches of the Himalayan Mountains and the most remote islands of the Pacific, disseminating the biological, cultural and social diversity that ecosystems and societies depend upon. In other words, migration is not the crisis - it is the solution.