We suggest that morbid jealousy falls on the extreme end of a jealousy continuum. Thus, many features associated with normal jealousy will be present in individuals diagnosed with morbid jealousy. We apply Boyer & Lienard's (B&L's) prediction one (P1; target article, sect. 7.1) to morbid jealousy, suggesting that fitness-related life-cycle dimensions predict sensitivity to cues, and frequency, intensity, and content of intrusive thoughts of partner infidelity. (Published Online February 8 2007).

Rape of women by men might be generated either by a specialized rape adaptation or as a by-product of other psychological adaptations. Although increasing number of sexual partners is a proposed benefit of rape according to the “rape as an adaptation” and the “rape as a by-product” hypotheses, neither hypothesis addresses directly why some men rape their long-term partners, to whom they already have sexual access. In two studies we tested specific hypotheses derived from the general hypothesis that sexual coercion (...) in the context of an intimate relationship may function as a sperm competition tactic. We hypothesized that men’s sexual coercion in the context of an intimate relationship is related positively to his partner’s perceived infidelities and that men’s sexual coercion is related positively to their mate retention behaviors (behaviors designed to prevent a partner’s infidelity). The results from Study 1 (self-reports from 246 men) and Study 2 (partner-reports from 276 women) supported the hypotheses. The Discussion section addresses limitations of this research and highlights future directions for research on sexual coercion in intimate relationships. (shrink)

Intra- and intergroup conflict are likely to have been recurrent features of human evolutionary history; however, little research has investigated the factors that affect men’s combat alliance decisions. The current study investigated whether features of previous one-on-one combat with an opponent affect men’s interest in allying with that opponent for future group combat. Fifty-eight undergraduate men recruited from a psychology department subject pool participated in a one-on-one laboratory fight simulation. We manipulated fight outcome, perceived fighter health asymmetry, and the presence (...) of a witness over six sets of five rounds of fighting. Following each set, we asked men how interested they would be in allying with their opponent for future group combat. We found that men were more interested in allying with their opponent for future group combat if their opponent won the fight or if a witness was present, but perceived fighter-health asymmetry did not affect men’s decision to ally with their opponent. Exploratory analyses revealed a two-way interaction between fight outcome and the presence of a witness, such that winners without a witness present expressed less interest in allying with their opponent for future group combat. Our findings suggest that men attend to the benefits of allying with a man who has demonstrated relatively superior fighting ability. Alliance with a previous opponent for group combat may vary with the relationship value of the opponent and the utility of demonstrating cooperativeness to third-party observers. These findings inform our understanding of coalition formation. (shrink)

Cuckoldry is an adaptive problem faced by parentally investing males of socially monogamous species (e.g., humans and many avian species). Mate guarding and frequent in-pair copulation (IPC) may have evolved as anti-cuckoldry tactics in avian species and in humans. In some avian species, the tactics are used concurrently, with the result that mate guarding behaviors and IPC frequency are correlated positively. In other avian species, the tactics are compensatory, with the result that mate guarding behaviors and IPC frequency are correlated (...) negatively. The relationship between mate guarding and IPC frequency in humans is unknown. Avian males that use these tactics concurrently share with human males an inability to guard a female partner continuously during her peak fertile period. We hypothesized, therefore, that men’s mate guarding and IPC frequency function as concurrent anti-cuckoldry tactics, resulting in a positive correlation between them. Study 1 (n=305) secured men’s self-reports of mate guarding and IPC frequency. Study 2 (n+367) secured women’s reports of their partners’ mate guarding and IPC frequency. The concurrent tactics hypothesis was supported in both studies: Men’s mate guarding and IPC frequency are correlated positively, and this association is not attributable to male age, female age, relationship satisfaction, relationship length, or time that the couple spends together. The Discussion section addresses potential limitations of this research and future research directions. (shrink)

Women who are abused by their male intimate partners incur many costs, ranging in severity from fleeting physical pain to death. Previous research has linked the presence of children sired by a woman’s previous partner to increased risk of woman abuse and to increased risk of femicide. The current research extends this work by securing data from samples of 111 unabused women, 111 less severely abused women, 128 more severely abused women, and 26 victims of intimate partner femicide from the (...) Chicago Women’s Health Risk Study to document an ordinal trend in the risk of experiencing more severe forms of violence for women who have children in the household sired by a previous partner. The discussion addresses two potential explanations for this trend and highlights directions for future research. (shrink)

Fincher & Thornhill (F&T) present a powerful case for the relationship between parasite-stress and religiosity. We argue, however, that the United States may be more religious than can be accounted for by parasite-stress. This greater religiosity might be attributable to greater sensitivity to immigration, which may hyperactivate evolved mechanisms that motivate avoidance of potential carriers of novel parasites.

Andrews et al. attempt to clarify the standards for determining whether traits are adaptations. The authors argue that tests of adaptationist hypotheses best proceed by assessing the consistency of the traits with the proposed standards. Critical tests of such standards must assess inconsistency – hypotheses must be falsifiable. To fully understand trait evolution, we must consider both adaptive and nonadaptive hypotheses.

We examine the self-deceptive aspects of religion and nationalism. By embracing various religious or political ideals, regardless of their truth, our ancestors could have enhanced their confidence, solidified their social ties, and manipulated their reproductive rivals. This use of culture as one's extended phenotype may increase the spread of misinformation and create global webs of deception and self-deception.

Young men are more distressed by a partner’s sexual infidelity, whereas young women are more distressed by a partner’s emotional infidelity. The present research investigated (a) whether the sex difference in jealousy replicates in an older sample, and (b) whether younger people differ from older people in their selection of the more distressing infidelity scenario. We presented forced-choice dilemmas to 202 older people (mean age = 67 years) and to 234 younger people (mean age = 20 years). The sex difference (...) replicated in the older sample. In addition, older women were less likely than younger women to select a partner’s emotional infidelity as more distressing than a partner’s sexual infidelity. Discussion offers directions for future work on sex differences and age differences in jealousy. (shrink)

Schmitt recognized that research is needed to identify other factors associated with sex ratio and with sociosexuality that may explain cross-cultural variation in sexual behavior. One such factor may be the risk of sperm competition. Sperm competition theory may lead us to a more complete explanation of cultural variation in sexual behavior.

Using data collected from people with at least one brother and one sister, and consistent with an evolutionary perspective, we find that older men and women (a) are more upset by a brother’s partner’s sexual infidelity than by her emotional infidelity and (b) are more upset by a sister’s partner’s emotional infidelity than by his sexual infidelity. There were no effects of participant sex or sex of in-law on upset over a sibling’s partner’s infidelities, but there was an effect of (...) participant sex on reports of upset over one’s own partner’s infidelities. The results suggest that the key variable among older participants is the sex of the sibling or, correspondingly, the sex of the sibling’s partner, as predicted from an evolutionary analysis of reproductive costs, and not the sex of the participant, as predicted from a socialization perspective. Discussion offers directions for future work on jealousy. (shrink)

Previous research suggests that individuals diagnosed with morbid jealousy have jealousy mechanisms that are activated at lower thresholds than individuals with normal jealousy, but that these mechanisms produce behavior that is similar to individuals with normal jealousy. We extended previous research documenting these similarities by investigating sex differences in partner-directed violence committed by individuals diagnosed with morbid jealousy. The results support some of our predictions. For example, a greater percentage of men than women diagnosed with morbid jealousy used physical violence, (...) attempted to kill, and actually killed their partners, and used their hands rather than an object to kill their partners. These results replicate results generated for individuals with normal jealousy. Discussion addresses implications of the current research and highlights directions for future research on the psychology of morbid jealousy. (shrink)

Archer's argument regarding sex differences in partner violence rests on a general account of between-sex differences in reproductive strategies and in social roles. However, men's partner-directed violence often is predicted by perceived risk of female infidelity. We hypothesize that men's partner-directed violence is produced by psychological mechanisms evolved to solve the adaptive problem of paternity uncertainty.

According to Williams, human facially expressed pain, and its perception by conspecifics, is generated by evolved mechanisms. We argue that a key variable – sex (male, female) – needs to be considered for a complete theory of pain expression and perception. To illustrate, we cite findings on sex differences in pain and pain perception, and in crying and crying responsiveness.

McKay & Dennett's (M&D's) description of beliefs, and misbeliefs in particular, is a commendable contribution to the literature; but we argue that referring to beliefs as adaptive or maladaptive can cause conceptual confusion. is inconsistently defined in the article, which adds to confusion and renders it difficult to evaluate the claims, particularly the possibility of.

This article introduces evolutionary psychology to a general readership, with the purpose of applying evolutionary psychology to suicide terrorism. Some of the key concepts related to evolutionary psychology are discussed, as well as several misconceptions associated with this approach to psychology. We argue that one of the primary, but insufficient, motivating factors for suicide terrorism is strong religious belief. Evolutionary psychological theories related to religious belief, and supporting empirical work, are described, laying a foundation for examining suicide terrorism. Several promising (...) directions for future research on suicide terrorism from an evolutionary psychological perspective are highlighted, particularly within the theoretical framework of kin selection, and the implications of applying evolutionary psychology to suicide terrorism are discussed. (shrink)

Female coital orgasm may be an adaptation for preferentially retaining the sperm of males with “good genes.” One indicator of good genes may be physical attractiveness. Accordingly, R. Thornhill, S. W. Gangestad, and R. Comer (1995) found that women mated to more attractive men reported an orgasm during a greater proportion of copulations than did women mated to less attractive men. The current research replicates this finding, with several design variations. We collected self-report data from 388 women residing in the (...) United States or in Germany. Results support the hypothesis that women mated to more attractive men are more likely to report an orgasm at the most recent copulation than are women mated to less attractive men, after statistically controlling for several key variables. Discussion addresses (a) the inability of the present research to specify the causal link between female orgasm and male attractiveness and (b) the proactive nature of female sexuality documented in recent research guided by an evolutionary perspective. (shrink)

McCullough et al. propose adaptations that motivate forgiveness when the potential benefits of continuing the relationship outweigh the costs incurred by the transgression. The costs incurred are definite, whereas future benefits of forgiveness are only probabilistic. This situation exposes the forgiver to cheating in the form of repeat transgression. Adaptations motivating genuine forgiveness are therefore unlikely to evolve.

In their classic study of differences in mating strategies, Clark and Hatfield (1989, Journal of Psychology and Human Sexuality, 2, 39–54) found that men and women demonstrated a striking difference in interest in casual sex. The current study examined the role of an imagined requestor’s physical attractiveness (slightly unattractive, moderately attractive, and exceptionally attractive) on men’s and women’s willingness to accept three different requests (go out, come to apartment, go to bed) as reflected in answers to a questionnaire. We tested (...) two hypotheses with a sample of 427 men and 443 women from three countries. Hypothesis 1 states that men, relative to women, will demonstrate a greater willingness to accept the “come to apartment” and “go to bed” requests but not the “go out” request for all three levels of requestor attractiveness. This hypothesis reflects Clark and Hatfield’s main findings. Hypothesis 2 states that the physical attractiveness of a potential partner will have a greater effect on women’s than on men’s willingness to accept all three requests, and particularly for the explicit request for casual sex. The results partially supported Hypothesis 1 and fully supported Hypothesis 2. The discussion highlights limitations of the current research and presents directions for future research. (shrink)

Men who spend a greater proportion of time apart from their female partner since the couple’s last copulation are at greater “objective” sperm competition risk. We propose a novel cue to sperm competition risk: the time she spends with her male friends. Four hundred and twenty men in a committed, heterosexual, sexual relationship completed a questionnaire. The results indicate that men at greater objective sperm competition risk report less time desired until the couple’s next copulation, greater interest in copulating with (...) their partner, and greater anger, frustration, and upset in response to their partner’s sexual rejection, but only among men whose partner spends more time with her male friends. These results remain after controlling statistically for the participant’s age and their partner’s age. We discuss limitations of the current research, and discuss how research in human sperm competition can inform social issues, including men’s partner-directed sexual coercion. (shrink)

Analyses of between-sex differences have provided a powerful starting point for evolutionarily informed work on human sexuality. This early work set the stage for an evolutionary analysis of within-sex differences in human sexuality. A comprehensive theory of human sexual strategies must address both between-sex differences and within-sex differences in evolved psychology and manifest behavior.

Krueger & Funder (K&F) presuppose that the base rate for social cognition is more rational than is indicated by research, and that a focus on cognitive errors and behavioral shortcomings is responsible for the fragmented nature of social psychology. Insight concerning both issues is forthcoming from advances in evolutionary psychology and the adaptation of dynamical systems theory to social psychology.

Atran & Norenzayan's (A&N's) target article effectively combines the insights of evolutionary biology and interdisciplinary cognitive science, neither of which alone yields sufficient explanatory power to help us fully understand the complexities of supernatural belief. Although the authors' ideas echo those of other researchers, they are perhaps the most squarely grounded in neo-Darwinian terms to date. Nevertheless, A&N overlook the possibility that the tendency to infer supernatural agents' communicative intent behind natural events served an ancestrally adaptive function.

Future work is needed to establish that pure short-term memory is a coherent individual difference attribute that is separable from traditional compound short-term memory measures. Psychometric support for latent pure short-term memory capacity will provide an important starting point for future fine-grained analyses of the intrinsic factors that influence individual differences in math skills.

According to Revonsuo, dreams are the output of a evolved “threat simulation mechanism.” The author marshals a diverse and comprehensive array of empirical and theoretical support for this hypothesis. We propose that the hypothesized threat simulation mechanism might be more domain-specific in design than the author implies. To illustrate, we discuss the possible sex-differentiated design of the hypothesized threat simulation mechanism. [Revonsuo].