Emotions can be explained as specialized states, shaped by natural selection, that increase fitness in specific situations. The physiological, psychological, and behavioral characteristics of a specific emotion can be analyzed as possible design features that increase the ability to cope with the threats and opportunities present in the corresponding situation. This approach to understanding the evolutionary functions of emotions is illustrated by the correspondence between (a) the subtypes of fear and the different kinds of threat; (b) the attributes of happiness (...) and sadness and the changes that would be advantageous in propitious and unpropitious situations; and (c) the social emotions and the adaptive challenges of reciprocity relationships. In addition to addressing a core theoretical problem shared by evolutionary and cognitive psychology, explicit formulations of the evolutionary functions of specific emotions are of practical importance for understanding and treating emotional disorders. (shrink)

Runaway social selection resulting from partner choice may have shaped aspects of human cooperation and complex sociality that are otherwise hard to account for. Social selection is the subtype of natural selection that results from the social behaviors of other individuals. Competition to be chosen as a social partner can, like competition to be chosen as a mate, result in runaway selection that shapes extreme traits. People prefer partners who display valuable resources and bestow them selectively on close partners. The (...) resulting phenotypic covariance between displays and preferences gives fitness advantages to both, creating runaway selection that could shape a whole suite of prosocial traits including altruism, moral capacities, empathy, and theory of mind. Even though they give a net fitness benefit, traits at the endpoint of runaway social selection can have substantial deleterious effects on other traits such as viability, ability to accumulate resources, or vulnerability to mental disorders. Social selection forces arising from self-interested partner choices may be an invisible hand that shaped capacities for commitment, altruism, and other prosocial capacities of the human social brain. (shrink)

The first ever description of how evolutionary principles can be applied to questions of health and sickness.

Sex differences in mortality rates stem from genetic, physiological, behavioral, and social causes that are best understood when integrated in an evolutionary life history framework. This paper investigates the Male-to-Female Mortality Ratio (M:F MR) from external and internal causes and across contexts to illustrate how sex differences shaped by sexual selection interact with the environment to yield a pattern with some consistency, but also with expected variations due to socioeconomic and other factors.

Despite the effort on DSM-5 and ICD-11, few appear satisfied with these classification systems. We suggest that the core reason for dissatisfaction is expecting too much from them; they do not provide discrete categories that map to specific causes of disease, they describe clinical syndromes intended to guide treatment choices. Here we review work on anxiety and anxiety disorders to argue that while clinicians draw a pragmatic distinction between normal and abnormal emotions based on considerations such as severity and duration, (...) understanding the evolutionary origins and utility of the emotions, including the adaptive value of adverse emotions, is key for formulating comprehensive assessments of an individual patient’s symptoms and for providing a conceptual foundation for pharmacotherapy, psychotherapy, and public health. (shrink)

Progress in emotions research requires understanding why debate about the general nature of emotions remains intractable. Much confusion arises from proposals that offer one of the four different kinds of biological explanation, without recognizing the need for other three. More arises from tacitly thinking of emotions as products of design, when they are actually organically complex products of natural selection. Finally, debate persists because of categorizing emotions by functions, instead of recognizing that each emotion was shaped by the adaptive challenges (...) posed by a recurring situation. No general explanation of the kind usually sought for emotions exists, however progress is possible if we study emotions as organically complex partially differentiated constellations of changes that have been useful in certain situations. (shrink)

Game theory has progressed from analysis of one-move games between two rational agents, to iterated n-person games in which strategies evolve, and actors use prior experience to coordinate their moves. The next step in this direction is to analyse commitment strategies. An individual can influence others by announcing his or her commitment to a future act that would not be in his or her best interests. Spiteful threats can coerce others. Promises to aid someone when nothing can be reciprocated can (...) create deep relationships. Such strategies are inherently paradoxical because the maximum payoff comes from not having to follow through on the commitment, and this is made more likely by expensive signalling of commitments to outlandish threats and promises whose plausibility declines with their magnitude. Nonetheless, the fitness benefits of subjective commitment are substantial and may well have shaped human capacities for revenge and spite, as well as deep attachment and genuine morality. (shrink)

Strong recent selection for social cognition may well explain the persistence of genes that predispose to schizophrenia. The specific mechanism responsible may be a skewed fitness function in which selection pushes the mean for advantageous mental traits perilously close to a “fitness cliff” where the system fails catastrophically in some individuals.

Genes are ‘selfish’ in that they make organisms whose behaviours are shaped, necessarily, to benefit their genes. But altruism and selfishness as we usually think of them have little to do with ‘evolutionary altruism’ and ‘evolutionary selfishness', and the use of these phrases has given rise to much confusion. The most pernicious is the false conclusion that individual altruism is impossible unless it has been shaped by group selection. In fact, human altruism and morality are shaped by genes because individuals (...) with these capacities have a fitness advantage. The advantage may come from sexual selection, social selection, or the advantages of a capacity for commitment, as well as from cooperation, and kin selection. Ironically, morality may be a metaphor so powerful that it inhibits careful thinking precisely because our brains are wired by natural selection to see the world in terms of good and evil. (shrink)

Expectations can facilitate rapid fear conditioning and this may explain some phenomena that have been attributed to preparedness. However, preparedness remains the best explanation for some aspects of clinical phobias and the difficulty of creating fears of modern dangers. Rapid fear conditioning based on expectancy is not an alternative to an evolutionary explanation, but has, like preparedness, been shaped by natural selection.

Most attempts to craft a definition of disease seem to have tackled two tasks simultaneously: 1) trying to create a series of inclusion and exclusion criteria that correspond to medical usage of the word disease and 2) using this definition to understand the essence of what disease is. The first task has been somewhat accomplished, but cannot reach closure because the concept of “disease” is based on a prototype, not a logical category. The second task cannot be accomplished by deduction, (...) but only by understanding how the body works and what each component is for, in evolutionary detail. An evolutionary view of the origins of the body and its vulnerabilities that result in disease provides an objective foundation for recognizing pathology. Our social definition of disease will remain contentious, however, because values vary, and because the label “disease” changes judgments about the moral status of people with various conditions, and their rights to medical and social resources. (shrink)