She argues that humans need face-to-face contact, as they need air and water. We have evolved for it, to the extent that those surrounded by a tight-knit group of friends who regularly gather to eat—and, crucially, gossip—live an average of 15 years longer than loners. Quality face-to-face contact is essential for a social species, Pinker writes, citing research that shows it fortifies immune systems, calibrates hormones and increases chances of surviving heart attacks, strokes, AIDS and cancer.