Evolutionary Theories of Emotion


Although numerous adaptive-evolutionary treatments of emotion have emerged over the years (e.g., Ekman & Davidson, 1994; Plutchik, 1994), an evolutionary-psychological approach distinguishes itself from other evolutionary approaches by adopting an explicitly adaptationist perspective (Barkow, Cosmides, & Tooby, 1992). An adaptationist perspective is guided by the simple assumption that the mind is comprised of many mental adaptations, each of which is the product of natural and sexual selection operating over many generations during the course of human evolution (Buss, Haselton, Shackelford, Bleske, & Wakefield, 1999).

Our ancestors faced a multitude of adaptive problems—evading predators, gathering food, finding shelter, attracting mates, caring for kin, and communicating with conspecifics, to name just a few (Barkow, Cosmides, & Tooby, 1992; Buss, in press). Because each of these adaptive problems required a unique solution (escaping a predator involves different skills than acquiring a mate), evolutionary psychologists argue that we should expect that our minds consist of a great variety of distinct psychological mechanisms, each shaped to address a specific adaptive challenge (Barrett, 2005; Symons, 1979). Similarly, we argue that it is reasonable to expect that humans have evolved a multitude of distinct emotions, each designed to deal with a specific set of adaptive problems.

Emotions affect the way that we think and behave in a variety of personal and social contexts (Clore, Schwarz, & Conway, 1994; Holmes & Anthony, this volume; Morris & Keltner, 2000; Zeelenberg & Pieters, 2005). Evolutionary approaches to emotion and social decision-making have ranged from broad theoretical models of emotion (Buck, 1999; Cosmides & Tooby, 2000; Tooby & Cosmides, 1990) to empirical investigations of specific emotions (Ketelaar & Au, 2003). One of the broadest theoretical approaches to emotion and decision-making (emotions-as-commitment devices) uses the tools of experimental economics to explore game-theoretic aspects of emotions. A second theoretical approach proposes that emotions are superordinate cognitive programs that coordinate thoughts and behaviors in response to specific adaptive challenges. We describe each of these approaches before turning to a brief review of recent empirical research linking specific emotions to specific adaptive problems.

Emotions as Commitment Devices

Humans can be coldly calculating and selfish, and like many animals, humans have preferences for immediate gains due to heavy discounting of the future (Ainslie, 1975; Ainslie & Herrnstein, 1981; Frederick, Loewenstein, & O’Donoghue, 2002). Theorists from Adam Smith (1759) to Robert Trivers (1971) and more recently economists Jack Hirschliefer (1987) and Robert Frank (1988), have argued that emotions operate as mechanisms for sustaining subjective commitments to strategies that run counter to speciously attractive immediate rewards. Frank summarized the logic of the theory as follows (Frank, 1988, p. 82):

The idea is that if the psychological reward mechanism is constrained to emphasize rewards in the present moment, the simplest counter to a specious reward from cheating is to have a current feeling that tugs in precisely the opposite direction. …because [the emotion] coincides with the moment of choice…it can negate the spurious attraction of the imminent material reward.

Frank illustrated this view with examples of how emotions such as love and guilt can influence social decision-making. When one experiences feelings of love for a romantic partner, for example, the immediate positive reward the emotion produces counteracts the pull of desire for an attractive other. Likewise, feelings of guilt immediately punish thoughts of selfishly cheating an ally and thus prevent the individual from compromising a cooperative relationship. In doing so, these emotions help us to stick with strategies that lead to rewards in the long run despite the fact that they often necessitate forgoing smaller immediate gains. For example, if one were drawn away from every possible romantic commitment by the prospect of finding a still more attractive mate, one could never reap the fitness benefits of long-term mateship, including cooperative child rearing (Hurtado & Hill, 1992; Marlowe, 2003; Pillsworth & Haselton, 2005) and assurance of mutual care in times of dire need (e.g., Nesse, 2001).

The bulk of the work on the commitment-device theory has been purely analytical (e.g., testing theoretical assumptions with mathematical models; see Hirshleifer, 1987, and Nesse, 2001, for reviews). Recently, however, this theory has also been subject to empirical tests. For example, in one study of the effects of guilt on cooperation, participants played an Ultimatum Game and emotions recorded after the first transaction were used to predict behavior one week later (Ketelaar, & Au, 2003). In an Ultimatum Game, participants are assigned the role of the proposer or respondent. The proposer is allotted a sum of money and allowed to give some percentage of it to the responder, who then decides whether to accept or refuse the offer. If the offer is accepted, the proposer and respondent split the money as proposed; if the offer is rejected neither party receives any money. In this study, the researchers found that over 90% of subjects who felt guilty after proposing an unfair offer (less than 50-50 split) reversed their behavior a week later and made a generous monetary offer (Ketelaar & Au, 2003). By contrast, less than 25% of the individuals who experienced no feelings of guilt made a similarly generous offer; in fact, the vast majority of them (> 75%) continued making selfish offers a week later. The effects of guilt on social decision-making observed in this study are consistent with the claim that individuals under the influence of certain emotions often make decisions that forego immediate benefits in favor of more profitable long-term outcomes (e.g., a cooperative alliance; Frank, 1988).

In sum, the immediate rewards or punishments that we feel when we experience certain emotions can serve as a potent counterweight to our tendency to overweight short-term gains. These emotions may appear irrational in the short run because they lead us to forgo sure gains, but ultimately they lead us to acquire still greater long-term benefits.

From Irrational Emotions or Emotional Wisdom? The Evolutionary Psychology of Emotions and Behavior by Martie G. Haselton and Timothy Ketelaar

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