The Social Psychology of Personal Relationships

Douglas T. Kenrick

and

Melanie R. Trost

Arizona State University, Tempe, AZ, USA

Evolutionary theory is arguably the most powerful set of ideas in the life sciences. No natural scientist studying the wing of a bat or the flipper of a seal or the long neck of a giraffe would ignore Darwin's theory of evolution by natural selection. Likewise for the behaviors of bats or seals or giraffes— obviously the unique bodies of these animals evolved to do something, and evolutionary theory helps to understand the co-evolution of physical morphology and behavior. Neither would many disagree that an evolutionary perspective is essential to understand the human body, with its upright posture, prehensile grasping hands, and large brain capable of producing complex language. Yet many social scientists have not yet realized that an evolutionary perspective is just as essential for a full understanding of human behavior. Just as bats are designed to survive by flying through the night sky, seals by swimming through the ocean depths, and giraffes by walking through the African plains, so human beings are designed to behave in certain ways in certain environments. To a large extent, humans are designed to live in social groups with other humans, and an evolutionary perspective can enhance our understanding of every aspect of personal relationships considered in this

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