The Kindness of StrangersAltruism is unique to the human species. It is also one of the great evolutionary puzzles, and we may be on the brink of solving it. It turns out that, over the last 12,000 years, we have become more and more altruistic. This is despite the fact that, the majority of the time, our minds are still breathtakingly indifferent to the welfare of others. In solving the enigma of generosity in a world of strangers, McCullough takes us on a sweeping history