For centuries, every person shared an equal right to the use of fields, forests, rivers and lakes. In Scandinavian countries like Sweden and Finland, this concept of ‘everyman’s right’ still holds. But the sharing of natural resources has led to devastating consequences for the environment and what some experts call the ‘Tragedy of the Commons’ - when several people act in their own self-interest, they end up depleting any shared resource even if it works against their own interest in the long-term. The world’s supplies of water, fish, oil and wood have all been squandered as a result. This week, Global Ideas reporter Julia Henrichmann explores how indigenous communities in Peru are working with experts to learn how to collectively use – but not overuse – their natural resources. In our background article, Eva Mahnke takes a look at celebrated political economist Elinor Ostrom’s unconventional approach towards managing shared resources.