Robin Dunbar is Professor of Evolutionary Anthropology at Oxford University and author of The Trouble with Science and How Many Friends Does One Person Need?

His latest book, The Science of Love and Betrayal (Faber, £12.99), assembles the evidence — including Internet surveys — about romantic love and mate choice. He believes the rise in Internet dating can prolong the ‘dreamphase’ of romance, when we lose touch with reality. One interesting point is that romantic relationships are so time-consuming that we often drop two of our most intimate friends — the intensity of feeling divides our time and attention.