An evolutionary psychological perspective on gender similarities and differences.
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Aggression↗
Biomedical subjects
Todd K Shackelford
Publications and source records attributed to Todd K Shackelford.
Comparative evolutionary psychology of sperm competition.
A comparative evolutionary psychological perspective predicts that species that recurrently faced similar adaptive problems may have evolved similar psychological mechanisms to solve these problems. Sperm competition provides an arena in which to assess the heuristic value of such a comparative evolutionary perspective. The sperm competition that results from female infidelity and polyandry presents a similar class of adaptive problems for individuals across many species. The authors first describe mechanisms of sperm competition in insects and in birds. They suggest that the adaptive problems and evolved solutions in these species provide insight into human anatomy, physiology, psychology, and behavior. The authors then review recent theoretical and empirical arguments for the existence of sperm competition in humans and discuss proposed adaptations in humans that have analogs in insects or birds. The authors conclude by highlighting the heuristic value of a comparative evolutionary psychological approach in this field.
Animals↗
Adding insult to injury: development and initial validation of the Partner-Directed Insults Scale.
Women who are verbally abused by their intimate male partners suffer serious mental health consequences and often experience physical violence in their relationship. Despite the importance of studying verbal abuse, no previous research has investigated the specific content of the insults men use to derogate their partners. We present the development and initial validation of a new measure designed to assess the specific content of insults used by men against their intimate partners. In a preliminary study, we used feedback from battered women, along with a review of the relevant literature, to identify specific insults for inclusion in the Partner-Directed Insults Scale (PDIS). We administered the PDIS to a sample of United States participants (Study 1) and a sample of New Zealand participants (Study 2), allowing for a cross-national investigation of the specific insults that men use to derogate their partners. The results demonstrate the practical need for such a scale and provide evidence for the discriminant validity of the PDIS by documenting that men's use of insults predicts their use of controlling behaviors and physical violence.
Adult↗
Evolutionary psychology and false confession.
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Biological Evolution↗
Partner killing by men in cohabiting and marital relationships: a comparative, cross-national analysis of data from Australia and the United States.
Using a national-level U.S. database, T. K. Shackelford (2001) calculated rates of uxoricide (the murder of a woman by her romantic partner) by relationship type (cohabiting or marital), by ages of the partners, and by the age difference between partners. Women in cohabiting relationships were 9 times more likely to be killed by their partner than were married women. Within marriages, the risk of uxoricide decreases with a woman's age. Within cohabiting relationships, middle-aged women were at greatest risk of uxoricide. The risk of uxoricide increased with greater age difference between partners. We sought to replicate the findings of Shackelford (2001) using a national-level database that includes information on more than 4,400 homicides that occurred in Australia between 1989 and 2002. Despite the higher rate of partner killing in the United States, and despite other cultural differences between the two countries, we replicated key patterns with the Australian data.
Adult↗
Sex differences in sexual psychology produce sex-similar preferences for a short-term mate.
We explored aspects of men's and women's short-term sexual psychology as a function of a potential short-term partner's relationship status. A total of 209 men and 288 women reported how likely they would be to pursue a casual sexual relationship with an attractive member of the opposite sex who was (1) married, (2) not married but has casual sexual partners, or (3) not married and has no casual sexual partners. Guided by sperm competition theory, we predicted and found that men prefer short-term sex partners who are not already involved in relationships and hence present a relatively low risk of sperm competition. Because women sometimes use short-term sexual relationships to acquire long-term partners, we predicted and found that women prefer short-term sexual partners who are not already involved in relationships and hence present relatively greater promise as a potential long-term partner. Finally, across each of the three levels of the imagined partner's relationship status, men reported a greater likelihood than did women of pursuing a casual sexual relationship. Discussion addressed methodological limitations and directions for future work.
Adult↗
Patterns and universals of mate poaching across 53 nations: the effects of sex, culture, and personality on romantically attracting another person's partner.
As part of the International Sexuality Description Project, 16,954 participants from 53 nations were administered an anonymous survey about experiences with romantic attraction. Mate poaching--romantically attracting someone who is already in a relationship--was most common in Southern Europe, South America, Western Europe, and Eastern Europe and was relatively infrequent in Africa, South/Southeast Asia, and East Asia. Evolutionary and social-role hypotheses received empirical support. Men were more likely than women to report having made and succumbed to short-term poaching across all regions, but differences between men and women were often smaller in more gender-egalitarian regions. People who try to steal another's mate possess similar personality traits across all regions, as do those who frequently receive and succumb to the poaching attempts by others. The authors conclude that human mate-poaching experiences are universally linked to sex, culture, and the robust influence of personal dispositions.
Adult↗
Methods of filicide: stepparents and genetic parents kill differently.
Stepparents commit filicide at higher rates than do genetic parents. According to M. Daly and M. I. Wilson (1994), motivational differences generate differences in the methods by which stepparents and genetic parents kill a child. Using Canadian and British national-level databases, Daly and Wilson (1994) found that stepfathers were more likely than genetic fathers to commit filicide by beating and bludgeoning, arguably revealing stepparental feelings of bitterness and resentment not present to the same degree in genetic fathers. Genetic fathers, in contrast, were more likely than stepfathers to commit filicide by shooting or asphyxiation, methods which often produce a relatively quick and painless death. We sought to replicate and extend these findings using a United States national-level database of over 400,000 homicides. Results replicate those of Daly and Wilson (1994) for genetic fathers and stepfathers. In addition, we identified similar differences in the methods by which stepmothers and genetic mothers committed filicide. Discussion addresses stepparental psychology in light of the current research, limitations of the current study, and future directions for research on this topic.
Child Abuse↗
Couple age discrepancy and risk of intimate partner homicide.
Although national level studies in the United States and Canada find that extreme partner age discrepancy is a risk factor for intimate partner homicide in opposite-sex couples, these studies carry two caveats: They are limited to cohabiting marital or common-law couples and they are not detailed enough to explore alternative explanations for the age discrepancy-homicide risk association. Using the Chicago Homicide Dataset, which includes all homicides that occurred in Chicago from 1965 to 1996, we analyze the 2,577 homicides in which the victim was killed by a current or former legal spouse, common-law spouse, or heterosexual boyfriend or girlfriend, and in which the woman was at least 18 years of age. Within each of 14 categories of couple age discrepancy, we estimate the population of intimate heterosexual couples and calculate the population-based risk of homicide. The results replicate national level findings showing that the risk of intimate partner homicide is considerably elevated for couples with a large discrepancy between their ages-where the man is at least 16 years older than the woman or the woman is at least 10 years older than the man. This risk pattern occurs regardless of whether the man or the woman was the homicide offender. We then investigate whether the link between partner age discrepancy and homicide risk is explained by the offender's arrest record. Results show that the higher risk of intimate partner homicide for age discrepant couples is robust, and does not depend on the previous arrest record of the offender. Discussion addresses other possible explanations for the increased risk of partner homicide for age discrepant couples, and the practical implications of these findings.
Adolescent↗
Men's sexual coercion in intimate relationships: development and initial validation of the Sexual Coercion in Intimate Relationships scale.
We report the development and initial validation of the Sexual Coercion in Intimate Relationships Scale (SCIRS), a measure designed to assess the prevalence and severity of sexual coercion in committed intimate relationships. We review existing measures of sexual coercion and discuss their limitations, describe the identification of the SCIRS items, perform a principal components analysis and describe the resulting three components, and present evidence for the convergent and discriminative validity of the SCIRS. Because sexual coercion in intimate relationships often takes the form of subtle tactics, the SCIRS items assess communicative tactics such as hinting and subtle manipulations in addition to tactics such as the use of physical force. The SCIRS provides researchers and clinicians with a valid, reliable, and comprehensive measure with which to study the dynamics of sexual coercion in intimate relationships.
Adult↗
Universal sex differences in the desire for sexual variety: tests from 52 nations, 6 continents, and 13 islands.
Evolutionary psychologists have hypothesized that men and women possess both long-term and short-term mating strategies, with men's short-term strategy differentially rooted in the desire for sexual variety. In this article, findings from a cross-cultural survey of 16,288 people across 10 major world regions (including North America, South America, Western Europe, Eastern Europe, Southern Europe, Middle East, Africa, Oceania, South/Southeast Asia, and East Asia) demonstrate that sex differences in the desire for sexual variety are culturally universal throughout these world regions. Sex differences were evident regardless of whether mean, median, distributional, or categorical indexes of sexual differentiation were evaluated. Sex differences were evident regardless of the measures used to evaluate them. Among contemporary theories of human mating, pluralistic approaches that hypothesize sex differences in the evolved design of short-term mating provide the most compelling account of these robust empirical findings.
Adult↗
Nifty ways to leave your lover: The tactics people use to entice and disguise the process of human mate poaching.
Although a number of studies have explored the ways that men and women romantically attract mates, almost no research exists on the special tactics people use when already in a relationship and trying to attract someone new--a process known as mate poaching enticement. In Study 1, the authors investigated the tactics people use to entice others into making mate poaching attempts. Enticement tactic effectiveness conformed to evolutionary-predicted patterns across sex and temporal context. In Study 2, the authors examined the tactics men and women use to disguise mate poaching enticement. The most effective camouflage for poaching also varied between sex in evolutionary-predicted ways, regardless of the target of deception (i.e., current partner vs. larger community). Discussion focuses on limitations of this research, future investigative directions, unexpected findings, and the utility of placing mate poaching attraction within the broader context of human sexual strategies.
Choice Behavior↗
Understanding domestic violence against women: using evolutionary psychology to extend the feminist functional analysis.
Evolutionary psychologists such as Wilson and Daly (1993b) hypothesize that one goal of male-perpetrated domestic violence is control over female sexuality, including the deterrence of infidelity. According to this hypothesis, domestic violence varies with women's reproductive value or expected future reproduction, declining steeply as women age. We tested this hypothesis with a sample of 3,969 cases of male-perpetrated partner-abuse reported to a single police precinct in a large urban area over a 14-year period. Results show that (a) rates of domestic violence decrease as women age, (b) younger men are at greatest risk for perpetrating domestic violence, (c) younger, reproductive age women incur nearly 10 times the risk of domestic violence as do older, post-reproductive age women, and (d) the greater risk of domestic violence incurred by reproductive age women is not attributable solely to mateship to younger, more violent men. Discussion addresses theoretical implications of these findings and suggests a refinement of the feminist hypothesis of domestic violence against women.
Adolescent↗
Toward an evolutionary forensic psychology.
Most theories of crime have not explored intensively biological and especially evolutionary explanations for criminal behavior. Ellis presents a valuable new perspective that proposes that attention to physiological mechanisms shaped by evolutionary forces can provide insights into the causes of crime and sex differences in the patterns of crime. We discuss other theories and research relevant to Ellis' theory. We also propose that an evolutionary psychological perspective of crime will help to invigorate research and lead to a better understanding of criminality. An integrated evolutionary forensic psychology will help to explain sources of conflict between individuals, situations in which conflict leads to victimization, and victim defenses and coping mechanisms.
Age Factors↗