The Search for Love in Human Evolution: Primate Social Bonds and a New Science of Emotion

Abstract

Love defines the human experience but often defies scientific study. Biological anthropologists flirt with the topic of love by studying monogamy and affiliative relationships. The interest in monogamy, I argue, is misplaced. But the interest in affiliative relationships is productive and deserves greater theoretical and methodological innovation. Social bonds have been carefully described for decades by primatologists, but I suggest that we still lack conceptual clarity and the crucial data needed to distinguish them from other types of relationships. A deeper understanding of social bonds, and pair bonds in particular, will be possible through the application of new methods to study affective states, or "emotions," in wild primates and other animals. By studying the emotions that underly various relationships, we will make progress toward answering prevailing questions about the origins and future of love, romance, and friendship.

Keywords: affect; friendship; monogamy; pair bonds.

FIGURE 1

A conceptual framework for understanding the main categories of love in humans (and, potentially, other animals).

FIGURE 2

Social relationships can be placed on two main axes. Relationships can range from affiliative to agonistic, which is displayed on the Y‐axis. Relationships can also range from brief to enduring, which is displayed on the X‐axis. Social bonds are affiliative and enduring, with pair bonds being even more affiliative and more enduring. Affiliation and agonism include an affective component, although scientists studying relationships in animals rarely quantify this and instead make tacit interpretations about whether the behavior is high/low arousal and is positive or negative.

FIGURE 3

Chimpanzees exhibit strong and enduring grooming relationships. Many of these occur between unrelated adult males. (a) Two adolescent male chimpanzees groom; (b) two high‐ranking males groom, which could suggest a “social bond” or an enduring alliance of utility; (c) two adult males, who have a very enduring relationship, groom. The younger brother of the male on the left looks at them several meters away.