Eleven predictions derived from the recalibrational theory of anger were tested. This theory prop... more Eleven predictions derived from the recalibrational theory of anger were tested. This theory proposes that anger is produced by a neurocognitive program engineered by natural selection to use bargaining tactics to resolve conflicts of interest in favor of the angry individual. The program is designed to orchestrate two interpersonal negotiating tactics (conditionally inflicting costs or conditionally withholding benefits) to incentivize the target of the anger to place greater weight on the welfare of the angry individual. Individuals with enhanced abilities to inflict costs (e.g., stronger individuals) or to confer benefits (e.g., attractive individuals) have a better bargaining position in conflicts; hence, it was predicted that such individuals will be more prone to anger, prevail more in conflicts of interest, and consider themselves entitled to better treatment. These predictions were confirmed. Consistent with an evolutionary analysis, the effect of strength on anger was greater for men and the effect of attractiveness on anger was greater for women. Also as predicted, stronger men had a greater history of fighting than weaker men, and more strongly endorsed the efficacy of force to resolve conflicts-both in interpersonal and international conflicts. The fact that stronger men favored greater use of military force in international conflicts provides evidence that the internal logic of the anger program reflects the ancestral payoffs characteristic of a small-scale social world rather than rational assessments of modern payoffs in large populations.
Evolutionary psychology : an international journal of evolutionary approaches to psychology and behavior, 2014
It is commonly assumed that judgments of dominance from faces partly rely on implicit judgments o... more It is commonly assumed that judgments of dominance from faces partly rely on implicit judgments of bodily strength. In two studies, we demonstrate such a relation for both computer-generated and natural photos of male faces. We find support when aggregating data across participants, when analyzing with hierarchical models, and also when strength and dominance are judged by different raters. Moreover, we identify common predictors that underlie perceptions of both strength and dominance: brow height, eye length, chin length, and the widths of the nose and mouth.
Recent research has shown that humans, like many other animals, have a specialization for assessi... more Recent research has shown that humans, like many other animals, have a specialization for assessing fighting ability from visual cues. Because it is probable that the voice contains cues of strength and formidability that are not available visually, we predicted that selection has also equipped humans with the ability to estimate physical strength from the voice. We found that subjects accurately assessed upper-body strength in voices taken from eight samples across four distinct populations and language groups: the Tsimane of Bolivia, Andean herder-horticulturalists and United States and Romanian college students. Regardless of whether raters were told to assess height, weight, strength or fighting ability, they produced similar ratings that tracked upper-body strength independent of height and weight. Male voices were more accurately assessed than female voices, which is consistent with ethnographic data showing a greater tendency among males to engage in violent aggression. Raters extracted information about strength from the voice that was not supplied from visual cues, and were accurate with both familiar and unfamiliar languages. These results provide, to our knowledge, the first direct evidence that both men and women can accurately assess men's physical strength from the voice, and suggest that estimates of strength are used to assess fighting ability.
This paper explores sex differences in interpersonal aggression among Aka foragers of the Central... more This paper explores sex differences in interpersonal aggression among Aka foragers of the Central African Republic (CAR). We tested whether male Aka physically aggressed more than female Aka, and whether female Aka indirectly aggressed more than male Aka, as evolutionary theories of aggression predict. To our knowledge, these are the first tests of these theories among an extant population of
Proceedings of the Royal Society B: Biological Sciences, 2010
Recent research has shown that humans, like many other animals, have a specialization for assessi... more Recent research has shown that humans, like many other animals, have a specialization for assessing fighting ability from visual cues. Because it is probable that the voice contains cues of strength and formidability that are not available visually, we predicted that selection has also equipped humans with the ability to estimate physical strength from the voice. We found that subjects accurately assessed upper-body strength in voices taken from eight samples across four distinct populations and language groups: the Tsimane of Bolivia, Andean herder-horticulturalists and United States and Romanian college students. Regardless of whether raters were told to assess height, weight, strength or fighting ability, they produced similar ratings that tracked upper-body strength independent of height and weight. Male voices were more accurately assessed than female voices, which is consistent with ethnographic data showing a greater tendency among males to engage in violent aggression. Raters extracted information about strength from the voice that was not supplied from visual cues, and were accurate with both familiar and unfamiliar languages. These results provide, to our knowledge, the first direct evidence that both men and women can accurately assess men's physical strength from the voice, and suggest that estimates of strength are used to assess fighting ability.
a b s t r a c t a r t i c l e i n f o Animals typically deploy their morphology during conflict t... more a b s t r a c t a r t i c l e i n f o Animals typically deploy their morphology during conflict to enhance competitors' assessments of their fighting ability (e.g. bared fangs, piloerection, dewlap inflation). Recent research has shown that humans assess others' fighting ability by monitoring cues of strength, and that the face itself contains such cues. We propose that the muscle movements that constitute the human facial expression of anger were selected because they increased others' assessments of the angry individual's strength, thereby increasing bargaining power. This runs contrary to the traditional theory that the anger face is an arbitrary set of features that evolved simply to signal aggressive intent. To test between these theories, the seven key muscle movements constituting the anger face were systematically manipulated one by one and in the absence of the others. Raters assessed faces containing any one of these muscle movements as physically stronger, supporting the hypothesis that the anger face evolved to enhance cues of strength.
Over human evolutionary history, upper-body strength has been a major component of fighting abili... more Over human evolutionary history, upper-body strength has been a major component of fighting ability. Evolutionary models of animal conflict predict that actors with greater fighting ability will more actively attempt to acquire or defend resources than less formidable contestants will. Here, we applied these models to political decision making about redistribution of income and wealth among modern humans. In studies conducted in Argentina, Denmark, and the United States, men with greater upper-body strength more strongly endorsed the self-beneficial position: Among men of lower socioeconomic status (SES), strength predicted increased support for redistribution; among men of higher SES, strength predicted increased opposition to redistribution. Because personal upper-body strength is irrelevant to payoffs from economic policies in modern mass democracies, the continuing role of strength suggests that modern political decision making is shaped by an evolved psychology designed for small-scale groups.
Proceedings of the Royal Society B: Biological Sciences, 2009
Selection in species with aggressive social interactions favours the evolution of cognitive mecha... more Selection in species with aggressive social interactions favours the evolution of cognitive mechanisms for assessing physical formidability (fighting ability or resource-holding potential). The ability to accurately assess formidability in conspecifics has been documented in a number of non-human species, but has not been demonstrated in humans. Here, we report tests supporting the hypothesis that the human cognitive architecture includes mechanisms that assess fighting ability-mechanisms that focus on correlates of upper-body strength. Across diverse samples of targets that included US college students, Bolivian horticulturalists and Andean pastoralists, subjects in the US were able to accurately estimate the physical strength of male targets from photos of their bodies and faces. Hierarchical linear modelling shows that subjects were extracting cues of strength that were largely independent of height, weight and age, and that corresponded most strongly to objective measures of upper-body strength-even when the face was all that was available for inspection. Estimates of women's strength were less accurate, but still significant. These studies are the first empirical demonstration that, for humans, judgements of strength and judgements of fighting ability not only track each other, but accurately track actual upper-body strength.
Proceedings of the National Academy of Sciences, 2009
Eleven predictions derived from the recalibrational theory of anger were tested. This theory prop... more Eleven predictions derived from the recalibrational theory of anger were tested. This theory proposes that anger is produced by a neurocognitive program engineered by natural selection to use bargaining tactics to resolve conflicts of interest in favor of the angry individual. The program is designed to orchestrate two interpersonal negotiating tactics (conditionally inflicting costs or conditionally withholding benefits) to incentivize the target of the anger to place greater weight on the welfare of the angry individual. Individuals with enhanced abilities to inflict costs (e.g., stronger individuals) or to confer benefits (e.g., attractive individuals) have a better bargaining position in conflicts; hence, it was predicted that such individuals will be more prone to anger, prevail more in conflicts of interest, and consider themselves entitled to better treatment. These predictions were confirmed. Consistent with an evolutionary analysis, the effect of strength on anger was greater for men and the effect of attractiveness on anger was greater for women. Also as predicted, stronger men had a greater history of fighting than weaker men, and more strongly endorsed the efficacy of force to resolve conflicts-both in interpersonal and international conflicts. The fact that stronger men favored greater use of military force in international conflicts provides evidence that the internal logic of the anger program reflects the ancestral payoffs characteristic of a small-scale social world rather than rational assessments of modern payoffs in large populations.
This paper explores sex differences in interpersonal aggression among Aka foragers of the Central... more This paper explores sex differences in interpersonal aggression among Aka foragers of the Central African Republic (CAR). We tested whether male Aka physically aggressed more than female Aka, and whether female Aka indirectly aggressed more than male Aka, as evolutionary theories of aggression predict. To our knowledge, these are the first tests of these theories among an extant population of hunter-gatherers. We also tested predictions of a recent evolutionary theory of physical strength, anger, and physical aggression. Data include a measure of upper body strength, age, sex, and qualitative views on aggression norms, as well as peer assessments of anger, physical aggression, and indirect aggression. Our results provide mixed support for the predicted sex differences in physical aggression and indirect aggression, and for the predicted relationships among anger, strength, and the use of aggression.
We propose that intuitions about modern mass-level criminal justice emerge from evolved mechanism... more We propose that intuitions about modern mass-level criminal justice emerge from evolved mechanisms designed to operate in ancestral small-scale societies. By hypothesis, individuals confronted with a crime compute two distinct psychological magnitudes: one that reflects the crime's seriousness and another that reflects the criminal's long-term value as an associate. These magnitudes are computed based on different sets of cues and are fed into motivational mechanisms regulating different aspects of sanctioning. The seriousness variable regulates how much to react (e.g., how severely we want to punish); the variable indexing the criminal's association value regulates the more fundamental decision of how to react (i.e., whether we want to punish or repair). Using experimental designs embedded in surveys, we validate this theory across several types of crime and two countries. The evidence augments past research and suggests that the human mind contains dedicated psychological mechanisms for restoring social relationships following acts of exploitation.
Does the human mind contain evolved concepts? Many psychologists have doubted this or have invest... more Does the human mind contain evolved concepts? Many psychologists have doubted this or have investigated only a narrow set of concepts (e.g., object, number, cause). Does the human mind contain evolved motivational systems? Many more assent to this claim, holding that there are evolved motivational systems for, among other tasks, social affiliation, aggressive competition, and avoiding predation. An emerging research program, however, reveals that these are not separate questions. Any evolved motivational system needs a wealth of conceptual structures that tether the motivations to real-world entities. For instance, what use is a fear of predators without knowing what predators are and how to respond to them effectively? As we illustrate with case studies of cooperation and conflict, there is no motivation without representation: To generate adaptive behavior, motivational systems must be interwoven with the concepts required to support them and cannot be understood without explicit reference to those concepts.
Theories from evolutionary biology have many implications for research in the cognitive sciences.... more Theories from evolutionary biology have many implications for research in the cognitive sciences. Evolutionary psychologists have been using these theories to guide their research, the goal of which is to map the evolved, species-typical cognitive and neural architecture of humans (and other species).
Eleven predictions derived from the recalibrational theory of anger were tested. This theory prop... more Eleven predictions derived from the recalibrational theory of anger were tested. This theory proposes that anger is produced by a neurocognitive program engineered by natural selection to use bargaining tactics to resolve conflicts of interest in favor of the angry individual. The program is designed to orchestrate two interpersonal negotiating tactics (conditionally inflicting costs or conditionally withholding benefits) to incentivize the target of the anger to place greater weight on the welfare of the angry individual. Individuals with enhanced abilities to inflict costs (e.g., stronger individuals) or to confer benefits (e.g., attractive individuals) have a better bargaining position in conflicts; hence, it was predicted that such individuals will be more prone to anger, prevail more in conflicts of interest, and consider themselves entitled to better treatment. These predictions were confirmed. Consistent with an evolutionary analysis, the effect of strength on anger was greater for men and the effect of attractiveness on anger was greater for women. Also as predicted, stronger men had a greater history of fighting than weaker men, and more strongly endorsed the efficacy of force to resolve conflicts-both in interpersonal and international conflicts. The fact that stronger men favored greater use of military force in international conflicts provides evidence that the internal logic of the anger program reflects the ancestral payoffs characteristic of a small-scale social world rather than rational assessments of modern payoffs in large populations.
Evolutionary psychology : an international journal of evolutionary approaches to psychology and behavior, 2014
It is commonly assumed that judgments of dominance from faces partly rely on implicit judgments o... more It is commonly assumed that judgments of dominance from faces partly rely on implicit judgments of bodily strength. In two studies, we demonstrate such a relation for both computer-generated and natural photos of male faces. We find support when aggregating data across participants, when analyzing with hierarchical models, and also when strength and dominance are judged by different raters. Moreover, we identify common predictors that underlie perceptions of both strength and dominance: brow height, eye length, chin length, and the widths of the nose and mouth.
Recent research has shown that humans, like many other animals, have a specialization for assessi... more Recent research has shown that humans, like many other animals, have a specialization for assessing fighting ability from visual cues. Because it is probable that the voice contains cues of strength and formidability that are not available visually, we predicted that selection has also equipped humans with the ability to estimate physical strength from the voice. We found that subjects accurately assessed upper-body strength in voices taken from eight samples across four distinct populations and language groups: the Tsimane of Bolivia, Andean herder-horticulturalists and United States and Romanian college students. Regardless of whether raters were told to assess height, weight, strength or fighting ability, they produced similar ratings that tracked upper-body strength independent of height and weight. Male voices were more accurately assessed than female voices, which is consistent with ethnographic data showing a greater tendency among males to engage in violent aggression. Raters extracted information about strength from the voice that was not supplied from visual cues, and were accurate with both familiar and unfamiliar languages. These results provide, to our knowledge, the first direct evidence that both men and women can accurately assess men's physical strength from the voice, and suggest that estimates of strength are used to assess fighting ability.
This paper explores sex differences in interpersonal aggression among Aka foragers of the Central... more This paper explores sex differences in interpersonal aggression among Aka foragers of the Central African Republic (CAR). We tested whether male Aka physically aggressed more than female Aka, and whether female Aka indirectly aggressed more than male Aka, as evolutionary theories of aggression predict. To our knowledge, these are the first tests of these theories among an extant population of
Proceedings of the Royal Society B: Biological Sciences, 2010
Recent research has shown that humans, like many other animals, have a specialization for assessi... more Recent research has shown that humans, like many other animals, have a specialization for assessing fighting ability from visual cues. Because it is probable that the voice contains cues of strength and formidability that are not available visually, we predicted that selection has also equipped humans with the ability to estimate physical strength from the voice. We found that subjects accurately assessed upper-body strength in voices taken from eight samples across four distinct populations and language groups: the Tsimane of Bolivia, Andean herder-horticulturalists and United States and Romanian college students. Regardless of whether raters were told to assess height, weight, strength or fighting ability, they produced similar ratings that tracked upper-body strength independent of height and weight. Male voices were more accurately assessed than female voices, which is consistent with ethnographic data showing a greater tendency among males to engage in violent aggression. Raters extracted information about strength from the voice that was not supplied from visual cues, and were accurate with both familiar and unfamiliar languages. These results provide, to our knowledge, the first direct evidence that both men and women can accurately assess men's physical strength from the voice, and suggest that estimates of strength are used to assess fighting ability.
a b s t r a c t a r t i c l e i n f o Animals typically deploy their morphology during conflict t... more a b s t r a c t a r t i c l e i n f o Animals typically deploy their morphology during conflict to enhance competitors' assessments of their fighting ability (e.g. bared fangs, piloerection, dewlap inflation). Recent research has shown that humans assess others' fighting ability by monitoring cues of strength, and that the face itself contains such cues. We propose that the muscle movements that constitute the human facial expression of anger were selected because they increased others' assessments of the angry individual's strength, thereby increasing bargaining power. This runs contrary to the traditional theory that the anger face is an arbitrary set of features that evolved simply to signal aggressive intent. To test between these theories, the seven key muscle movements constituting the anger face were systematically manipulated one by one and in the absence of the others. Raters assessed faces containing any one of these muscle movements as physically stronger, supporting the hypothesis that the anger face evolved to enhance cues of strength.
Over human evolutionary history, upper-body strength has been a major component of fighting abili... more Over human evolutionary history, upper-body strength has been a major component of fighting ability. Evolutionary models of animal conflict predict that actors with greater fighting ability will more actively attempt to acquire or defend resources than less formidable contestants will. Here, we applied these models to political decision making about redistribution of income and wealth among modern humans. In studies conducted in Argentina, Denmark, and the United States, men with greater upper-body strength more strongly endorsed the self-beneficial position: Among men of lower socioeconomic status (SES), strength predicted increased support for redistribution; among men of higher SES, strength predicted increased opposition to redistribution. Because personal upper-body strength is irrelevant to payoffs from economic policies in modern mass democracies, the continuing role of strength suggests that modern political decision making is shaped by an evolved psychology designed for small-scale groups.
Proceedings of the Royal Society B: Biological Sciences, 2009
Selection in species with aggressive social interactions favours the evolution of cognitive mecha... more Selection in species with aggressive social interactions favours the evolution of cognitive mechanisms for assessing physical formidability (fighting ability or resource-holding potential). The ability to accurately assess formidability in conspecifics has been documented in a number of non-human species, but has not been demonstrated in humans. Here, we report tests supporting the hypothesis that the human cognitive architecture includes mechanisms that assess fighting ability-mechanisms that focus on correlates of upper-body strength. Across diverse samples of targets that included US college students, Bolivian horticulturalists and Andean pastoralists, subjects in the US were able to accurately estimate the physical strength of male targets from photos of their bodies and faces. Hierarchical linear modelling shows that subjects were extracting cues of strength that were largely independent of height, weight and age, and that corresponded most strongly to objective measures of upper-body strength-even when the face was all that was available for inspection. Estimates of women's strength were less accurate, but still significant. These studies are the first empirical demonstration that, for humans, judgements of strength and judgements of fighting ability not only track each other, but accurately track actual upper-body strength.
Proceedings of the National Academy of Sciences, 2009
Eleven predictions derived from the recalibrational theory of anger were tested. This theory prop... more Eleven predictions derived from the recalibrational theory of anger were tested. This theory proposes that anger is produced by a neurocognitive program engineered by natural selection to use bargaining tactics to resolve conflicts of interest in favor of the angry individual. The program is designed to orchestrate two interpersonal negotiating tactics (conditionally inflicting costs or conditionally withholding benefits) to incentivize the target of the anger to place greater weight on the welfare of the angry individual. Individuals with enhanced abilities to inflict costs (e.g., stronger individuals) or to confer benefits (e.g., attractive individuals) have a better bargaining position in conflicts; hence, it was predicted that such individuals will be more prone to anger, prevail more in conflicts of interest, and consider themselves entitled to better treatment. These predictions were confirmed. Consistent with an evolutionary analysis, the effect of strength on anger was greater for men and the effect of attractiveness on anger was greater for women. Also as predicted, stronger men had a greater history of fighting than weaker men, and more strongly endorsed the efficacy of force to resolve conflicts-both in interpersonal and international conflicts. The fact that stronger men favored greater use of military force in international conflicts provides evidence that the internal logic of the anger program reflects the ancestral payoffs characteristic of a small-scale social world rather than rational assessments of modern payoffs in large populations.
This paper explores sex differences in interpersonal aggression among Aka foragers of the Central... more This paper explores sex differences in interpersonal aggression among Aka foragers of the Central African Republic (CAR). We tested whether male Aka physically aggressed more than female Aka, and whether female Aka indirectly aggressed more than male Aka, as evolutionary theories of aggression predict. To our knowledge, these are the first tests of these theories among an extant population of hunter-gatherers. We also tested predictions of a recent evolutionary theory of physical strength, anger, and physical aggression. Data include a measure of upper body strength, age, sex, and qualitative views on aggression norms, as well as peer assessments of anger, physical aggression, and indirect aggression. Our results provide mixed support for the predicted sex differences in physical aggression and indirect aggression, and for the predicted relationships among anger, strength, and the use of aggression.
We propose that intuitions about modern mass-level criminal justice emerge from evolved mechanism... more We propose that intuitions about modern mass-level criminal justice emerge from evolved mechanisms designed to operate in ancestral small-scale societies. By hypothesis, individuals confronted with a crime compute two distinct psychological magnitudes: one that reflects the crime's seriousness and another that reflects the criminal's long-term value as an associate. These magnitudes are computed based on different sets of cues and are fed into motivational mechanisms regulating different aspects of sanctioning. The seriousness variable regulates how much to react (e.g., how severely we want to punish); the variable indexing the criminal's association value regulates the more fundamental decision of how to react (i.e., whether we want to punish or repair). Using experimental designs embedded in surveys, we validate this theory across several types of crime and two countries. The evidence augments past research and suggests that the human mind contains dedicated psychological mechanisms for restoring social relationships following acts of exploitation.
Does the human mind contain evolved concepts? Many psychologists have doubted this or have invest... more Does the human mind contain evolved concepts? Many psychologists have doubted this or have investigated only a narrow set of concepts (e.g., object, number, cause). Does the human mind contain evolved motivational systems? Many more assent to this claim, holding that there are evolved motivational systems for, among other tasks, social affiliation, aggressive competition, and avoiding predation. An emerging research program, however, reveals that these are not separate questions. Any evolved motivational system needs a wealth of conceptual structures that tether the motivations to real-world entities. For instance, what use is a fear of predators without knowing what predators are and how to respond to them effectively? As we illustrate with case studies of cooperation and conflict, there is no motivation without representation: To generate adaptive behavior, motivational systems must be interwoven with the concepts required to support them and cannot be understood without explicit reference to those concepts.
Theories from evolutionary biology have many implications for research in the cognitive sciences.... more Theories from evolutionary biology have many implications for research in the cognitive sciences. Evolutionary psychologists have been using these theories to guide their research, the goal of which is to map the evolved, species-typical cognitive and neural architecture of humans (and other species).
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Papers by Aaron Sell