Our work on social thermoregulation was extensively covered in the March 2017 issue of the Scientific American Mind. In “The Warmth of Friendship, The Chill of Betrayal”, Marta Zaraska writes extensively about the evolutionary advantages of sharing body heat and what the consequences are for modern relationships. She also contrasts this/our perspective with more cognitive, conceptual metaphor-like theories (see here and here for some criticisms of Conceptual Metaphor Theory, and here for a recent update how social thermoregulation does work). A short excerpt:
“The big question, of course, is why? Why are physical and psychological temperatures linked in the first place? There are two theories, which are not necessarily mutually exclusive. “One notion is that from birth we’ve learned that warmth signals the presence of loved ones, so one experience brings to mind the other one,” Inagaki says. “The second theory is that it’s part of our innate system.”
For years researchers have explained the connection by way of the first theory, but recent neurobiological evidence gives more weight to the second idea that we have evolved this way. “For all warmblooded animals, temperature regulation is very metabolically expensive and also required for survival,” IJzerman points out. “But it becomes cheaper when there are others to help us regulate our temperature.”
Indeed, animal research has revealed that kleptothermy—or stealing warmth from others, much as huddled emperor penguins do in Antarctica—saves metabolic resources. One 2014 study estimated that in a species of Chilean rodents, sharing a cage with just a few other animals lowered an individual’s basal metabolic rate by up to 40 percent. Similarly, a 2015 study of vervet monkeys showed that friendly grooming not only helps these animals with tangles and pests, it also renders their pelts better insulated against the cold.
If we can save precious energy and feel warmer among others, it makes sense that we would also feel more socially included and trusting when primed with physical warmth. “Throughout evolutionary time, if you needed somebody else to cuddle with, you needed to know how reliable they were,” IJzerman explains, “so temperature expectation became involved as a ‘sociometer’ to assess how we think of other people. Despite modern conveniences like central heating, thermoregulation has remained important for how we understand our relationships, which is why in English we refer to emotionally responsive people as ‘warm’ and emotionally unresponsive as ‘cold.’”