The Evolution of Friendship

Psychologists have been trying to understand why we're just so good at helping each other out. One of the best explanations for why people help each other is called reciprocal altruism. If I help you out, then a bit later you help me out, and we've both sort of increased our fitness - but it's not always clear if they'll return the favour or not. You no longer really have to bother remembering every time you've helped them or they've helped you just come to trust them that they will return the favour later. Lewis: We can end up in the same way that we're exporting our manufacturing to another country and then saying, look, we've cut how carbon emissions