As an excellent new book makes clear, migrants are a force for good.1 This is just as well: all of us are descended from the migrants who left Africa 50 000 to 60 000 years ago. But there’s a downside. If migration is nearly as old as humanity itself, so is the hostility that outsiders face from their adoptive societies.

The United Kingdom distinguishes itself by being more opposed to immigration than similar countries with higher proportions of foreign born citizens. Underpinning this attitude is a host of assumptions that don’t fit the facts. A few examples. A recent report from the National Institute of Economic and Social Research contradicts the widespread belief that immigrants “cost jobs.”2 Migrants are actually less likely to claim working age benefits than British nationals. A Migration Observatory poll found that asylum seekers loom large when the British public thinks about migrants coming to live in Britain, yet applications for asylum made up just 3% of immigrant numbers in 2010. Despite its daily contact with the NHS, the British public seems oblivious to the fact that 37% of its doctors and 13% of its nurses are foreign born (figures from …