Heartwarming

Few things soothe like a hot drink in hand, yet it is not obvious how a warm mug could change how we feel. Social psychologist Hans Rocha IJzerman approaches this question from an evolutionary angle. Keeping the body at a stable temperature ranks among an animal's most basic needs, close to breathing. Much as penguins huddle together for warmth, humans have long depended on one another to stay warm, and over thousands of years this drive has helped shape how we live and what we build together.

Temperature played a part in human evolution, from the move to upright walking and the loss of body fur to the growth of our large brains, and it still affects us in surprising ways. The route from a warm cup to a shift in mood is indirect. Studies have found that a cold deliberation room may make jurors more inclined to convict, and that a chilly day may raise the chances someone purchases a home. The connection also runs the other way: thinking about warm, caring people can make us feel physically warmer.

IJzerman argues that our unconscious efforts to keep our bodies within a comfortable range can guide our relationships, our work, and even how we behave on social media. He explores how temperature affects social life and asks new questions. How might climate change reshape society? Why do some people feel chronically cold while others feel too hot? Can regulating temperature help people stay connected across a distance? The answers aim to help readers better understand their bodies, their minds, and the people around them.

The book is organized as a wide-ranging tour of the human world viewed through the contrast between coldness and warmth.