A new take on the games people play in their relationships

Human nature has deep evolutionary roots and is manifested in relationships with family members, friends, romantic and business partners, competitors, and strangers more than in any other aspects of behavior or intellectual activity, contends a University of Chicago behavioral biologist.

"Social behavior is, in part, genetically controlled and evolves by natural selection," said Dario Maestripieri, Professor of Comparative Human Development and Evolutionary Biology.

In some cases, natural selection has come up with the same solutions to similar social problems in organisms as evolutionarily distant as people and fish. In other cases, humans use the social strategies they genetically inherited from the ancestors shared with other primates. As a result of this shared inheritance, some of the "games" people play in their social relationships are also played by monkeys and apes.

In his new book, Games Primates Play: An Undercover Investigation of the Evolution and Economics of Human Relationships, Maestripieri shows that human social behavior can be explained by using the theories that economists and evolutionary biologists developed, and by looking at the behavior of monkeys and apes.

Game theory models used by economists, for instance, explain under what circumstances people and monkeys choose to cooperate or cheat with their partners, and when they choose to pick a fight with a bully or to retreat.

"The same cost-benefit analyses that explain different strategies used by male macaques to become the alpha male in a group they have just joined can also explain different strategies new employees can use to climb the power ladder in their company," he said.

"The same laws of supply and demand that determine how people pair up in the marriage market or the online dating market also regulate the social markets in which monkeys trade grooming for sex or other services with one another," he added.

Maestripieri has studied primate social behavior for 25 years and said he wrote the book because he has been fascinated by the behavior of people around him all his life. Looking at human relationships through the lens of primate behavior provides insights into a variety of everyday experiences, Maestripieri points out.

When strangers ride in an elevator, for instance, they act like two unfamiliar monkeys that have been placed together in a cage. In both cases, the two individuals avoid eye contact at all costs to reduce risk of aggression, or they exchange grooming (or its human equivalent, small talk) to alleviate the tension of the situation.

Maestripieri suggests that when people exchange emails with someone they know, certain unspoken rules about dominance explain how quickly they reply to messages, how long the replies are, and whether they are likely to terminate the email conversation — the same rules regulate the exchange of grooming behavior between dominant and subordinate individuals in rhesus macaques or chimpanzees.

"Show me your emails, and I will tell you whether you are on the fast track to become a leader of your company, or whether it's unlikely that you will have secretaries answering your email anytime soon," Maestripieri writes.

Both people and monkeys, Maestripieri argues, sometimes use intrusive, annoying, stressful or risky behaviors to test the strength of their social bonds with their partners. Exchanging intimacies such as passionate kisses, for instance, allows two lovers to test each other's willingness to tolerate impositions, and therefore their commitment to the relationship. It is similar to how a capuchin monkey tests the strength of its bond with another monkey by sticking a finger up the other's nose and waiting for a reaction.

Cooperative relationships — whether marital relationships, business partnerships or political alliances — play a major role in survival and success in human societies. "Natural selection has favored emotional processes that motivate and enhance an individual's ability to engage in, and profit from, cooperative enterprises," Maestripieri writes. Finding a good partner for cooperation, maintaining a reciprocal exchange of favors and avoiding being cheated are examples of the social problems with which humans cope.

Since many social problems are ancient, humans use ancient solutions to solve them. "When we confront everyday social problems, we resort to the ancient emotional, cognitive and behavioral algorithms that crowd our minds, and often let this automatic pilot help us navigate through the difficult and dangerous, but always fascinating, waters of human social affairs," Maestripieri concludes in his book which is published by Basic Books.