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Sexual Conflict After pressure would also lead to men and women fac- Conception ing different adaptive problems during a . A major sex-specific conflict that can arise centers T. Joel Wade, Kelsey Salerno and James Moran around the issue of paternity certainty. Evolution- Department of Psychology ary psychologists point out that worldwide cuck- Bucknell University, Lewisburg, PA, USA oldry rates range from 1.7% to 29.8% (Anderson 2006; Shackelford and Goetz 2007). Additional related conflicts such as , decrease in The Adaptive Function of Marital intercourse frequency, kin resemblance, the Dissatisfaction During Child–Rearing 4-year itch, and infidelity may also arise after conception. It can be argued that the dissatisfaction that occurs Research by Lucas et al. (2008) suggests some in a marriage serves an adaptive function cultural and evolutionary components to marital (Shackelford and Buss 1997). Pair-bonding satisfaction in general. This research reveals that among humans, in particular a union of marriage, there may be some universal component to effec- likely evolved to increase the reproductive bene- tive communication skills when it comes to rais- fits for both sexes (Betzig 1989; Buss and Schmitt ing an offspring, which would have been adaptive 1993). If a marriage is not maximizing the poten- in order to successfully raise a child. This theory is tial benefits and the costs that incur from the further extended by Cox et al. (1999), who found relationship outweigh the benefits, then the dissat- that those couples who had at least one partner isfaction that arises would serve to bring aware- with positive problem-solving skills prenatally ness of the issues that occur in the marriage. If a had higher marital satisfaction than those couples couple decides that a relationship is no longer in which neither partner showed this set of skills. beneficial, then the negative emotions associated Those couples with better problem-solving skills with this dissatisfaction would cause one or both also reported less of a drop in how satisfied they of the individuals involved to either address the were after the child was born. problems or to end the current relationship to find a more beneficial partnership. The adaptive challenges for both sexes during Violence During a union following conception would have been mate retention and the care of offspring. Since Violence during pregnancy has been seen men and women have different reproductive strat- throughout history, often being viewed as a egies (Buss 1989a), those differences in selective product of a patriarchal society. However,

# Springer International Publishing AG, part of Springer Nature 2018 T. K. Shackelford, V. A. Weekes-Shackelford (eds.), Encyclopedia of Evolutionary Psychological Science, https://doi.org/10.1007/978-3-319-16999-6_2014-1 2 Sexual Conflict After Conception evolutionary psychologists view violence during attempt to kill the offspring, thus terminating the pregnancy as a product of male sexual pregnancy. stemming from anxiety that the child their partner Prior research indicates that when a man has is carrying is not theirs (Deacy and McHardy sex with a spouse, he establishes sexual prece- 2013). Since men do not have paternity certainty, dence over her giving him access to her future they may resort to violence against their partner. sexuality (Shotland and Goodstein 1992). This For women, there is certainty of paternity because also happens when a man impregnates a spouse fertilization is internal, and women carry the child. (Sales and Murphy 2000). This sexual precedence Men, however, can be cuckolded and wind up can be interpreted from an evolutionary perspec- contributing resources to a child who is his genetic tive where it occurs to try to ensure paternity offspring. certainty and monopolize a spouse’s reproductive Cuckoldry ultimately decreases a man’s fitness potential. and increases another man’s fitness. This potential Male feelings of sexual precedence can also of being cuckolded is why men are often more lead to abuse in the form of threats (McFarlane upset if their partner commits sexual infidelity et al. 2002). Communicating threats to a pregnant rather than emotional infidelity (Kuhle 2011). spouse may serve as a method of mate retention Upon discovering that a man’s partner has become designed to lower her mate value in her eyes pregnant by someone else, the said man may which makes it harder for her to feel she can direct violence against his partner to kill the devel- attract another quality mate, keeping her with the oping offspring (Friedman and Shackelford 1999 father of her offspring. McKibbin et al. (2007) as cited in Buss and Duntley 2011). indicate that men can insult their intimate partners Given this risk intimate partner violence is as a form of mate retention. But, this has not been twice as likely in response (Burch and Gallup tested with men and their pregnant spouses/ 2004), and the prevalence of intimate partner vio- partners. lence during pregnancy ranges from 1% to 20% (Gazmararian et al. 1996). Cross-culturally, this statistics holds true also. A South African study After Delivery: Resemblance to Kin as a indicates that at least 20% of women experience at Decision–Maker to Investment least one act of physical violence during their pregnancy (Groves et al. 2015). Additionally, Due to paternity uncertainty, men may never women who are abused are more likely to be know if the child they are providing resources pregnant with another man’s child (Martin et al. for is his genetically related offspring. But, one 2004). Similarly, longitudinal research indicates way a man may seek to resolve this issue is via that partner jealousy and partner suspicion of infi- resemblance between him and his offspring. delity are strongly correlated with intimate partner Research indicates that when families observe violence (IPV) (Hellmuth et al. 2013). These find- newborn babies, both the mother and her family ings clearly show that abuse during pregnancy can claim the newborn looks like the father (Daly and be attributed in part to a man’s suspicion of infi- Wilson 1982). This represents an underlying delity on the part of his partner. mechanism attuned to familial resemblance of From this previous research, one may reason the father in order to facilitate that IPV could be seen as a form of infanticide by the father. Research supports this. Burch and also. While abuse may seem to be directed toward Gallup (2000) report that violence directed to the the woman herself, a Nicaraguan study indicates child and the mother is negatively correlated with half of the women who were pregnant and sub- a greater sense of paternal resemblance. Also, men jected to violence were injured from attacks react in a more positive manner and invest more, directed to their abdomen (Valladares et al. hypothetically, when an offspring resembles them 2005). The abdomen may be targeted in an (Platek et al. 2002, 2003). As paternal resem- blance and mate fidelity increase, so does the Sexual Conflict After Conception 3 increase in investment to the offspring (Apicella reports of above average marital satisfaction. and Marlowe 2004). Furthermore, the area of Research shows that married couples experience men’s brains that play a role in decision-making a decrease in satisfaction and confidence in their respond differently to resemblance, compared to relationship and an increase in negative commu- women’s brains (Platek et al. 2004). These find- nication and poor conflict management (Doss ings suggest that facial resemblance is an impor- et al. 2009). tant factor for paternal investment in offspring and From an evolutionary perspective, the decline as such suggest that kin resemblance may play a in satisfaction due to conflict can be accounted for role in conflict after conception occurs. by selective pressures. For example, men take the role of fatherhood more negatively than women (Gray and Crittenden 2014), since men typically Problems After the First Child are more interested in short-term mating (Buss and Schmitt 1993), consistent with parental Four-Year Itch investment theory. A woman may not be as Couples often have a decline in marital happiness stressed with the arrival of a child because she is after approximately 4 years (Fisher 1989; Kurdek more interested in long-term mating (Buss and 1999), and researchers have speculated that it Schmitt 1993) and because she is certain that the could be the outcome of boredom in a marriage offspring is hers, whereas men may not have (Kurdek 1999). From an evolutionary perspec- paternity certainty (Trivers 1972). tive, there may be a biological drive for a new In our current world, children are also weaned partner after 4 years because 4 years are the typ- earlier than they were in ancestral societies which ical amount of time needed to ensure the survival lead to more involvement in child-rearing from of the hominid infant through weaning (Fisher the father. This adds an additional stressor of an 1989). Infants are altricial when they are born increased need for cooperation between parents to and require an extensive amount of care. There- raise their young. This stressor likely contributes fore, infants are mother nurses, and nursing stim- to fathers experiencing less marital satisfaction ulates a release of oxytocin which facilitates (Doss and Rhoades 2017). attachment between mother and infant (Feldman Other moderating factors that may also con- et al. 2007; Galbally et al. 2011). tribute to increased conflict and decreased marital satisfaction are the gender of the parent, the age of Transition to Parenthood (TTP) offspring, and the number of offspring (Twenge Prior to having their first child, the couple begins et al. 2003). Correlational data indicate that to make plans and anticipate the future with one women typically have less marital satisfaction another, and after the birth of the first child, they than men. Furthermore, women who had infants experience joy but also experience negative also reported less satisfaction than women who effects like an extreme focus on their health and did not have infants, while those women with the offspring’s health. Additionally, they experi- infants had only a slight difference in reports of ence a decline in income and an increase in labor satisfaction compared to those women with older (Myrskylä and Margolis 2014). Given this con- children. The age of children did not affect men’s flict, not surprisingly, when a child is born, it has marital satisfaction. Furthermore, those parents negative impacts on the couple’s marital relation- who had a greater number of children also ship (Belsky et al. 1983). In fact, Kurdek (1999) revealed less marital satisfaction (Twenge et al. reports that couples with children experience the 2003). Overall, this research suggests that parents steepest decline in marital quality. Similarly, with multiple children and women with children Twenge et al. (2003) in a meta-analysis from have less marital satisfaction than parents with 148 samples report that across 90 studies parents one child and childless women. had less marital satisfaction than non-parents, As Trivers (1972) details, there is a sex differ- with a 10% difference among these groups in the ence when it comes to parental investment. 4 Sexual Conflict After Conception

Fertilization and gestation occur internally for additional conflicts may arise because women females, with male’s minimal contribution to hav- have less time to devote to child-rearing and ing offspring being . After birth, may need additional support from the child’s women are the providers of nutrients to the child father. through breastfeeding, which in previous times occurred for the first 3–4 years of a child’s life. Sex After the First Child From a parental investment theory perspective, it A common feature throughout the human popula- is not surprising that women with younger chil- tion is a decline in sexual intercourse (Brewis and dren have less marital satisfaction since they have Meyer 2005). Before the birth of the child, to devote greater time and effort to care for a women’s sexual interest and activity declines dur- younger child. The mothers also tend to do signif- ing the first trimester and continues to decrease icantly more housework, 9 h more than their into the third trimester (von Sydow 1999). Addi- childless counterparts, while fathers only com- tionally, after the child is born, sexual interest is pleted an hour more than those childless men usually lower than normal for several months. (Nomaguchi and Milkie 2003). This dissatisfac- Furthermore, research on women’s sexual interest tion can be offset by a husband who invests more indicates that they have less of a desire to have sex in the child by dedicating more time to the rearing after having children (Brewis and Meyer 2005; of the child (Gjerdingen and Chaloner 1994). Abdool et al. 2009; Escasa-Dorne et al. 2013). A greater investment by a male into his offspring Men’s sexuality also shifts during the TTP. is something women typically look for when Although they do have a satisfying , choosing a mate (Buss 1989a). Therefore the men’s sex drive is more inconsistent after the greater investment by a man would fulfill this first child is born (Gray et al. 2015). This preference and cause less strategic interference decreased on the part of men can be due among the couple (Buss 1989b, 2001). Overall, to a decrease in testosterone since men’s testoster- there would be less conflict because the burden of one goes down after they have a child (Gray et al. child-rearing and care would be lessened. 2002). Since men and women, respectively, are Socioeconomic status (SES) is another moder- less interested in sex after a child is born and ator variable that affects marital conflict and sat- sexuality in personal relationships is the result of isfaction. Twenge et al. (2003) report that parents an underlying motivation to maximize the trans- of higher SES, as well as the cohort of parents mission of genes to succeeding generations from the newer generation, reported greater mar- (Sprecher and Cate 2004), conflicts can arise ital dissatisfaction. The authors suggest that these regarding the amount of sex desired. Long et al. findings may be explained using two models: role (1996) report that sexual conflict is negatively conflict model and restriction of freedom models. related to relationship satisfaction. It may be that greater emphasis that is put on autonomy (Frum 2000), as well as an increase in the choice of activities that can be restricted when and Jealousy one becomes a parent, that contribute to greater dissatisfaction in marriage. The role that each sex Two common types of infidelity that occur in typically takes on when it comes to parental relationships are sexual and emotional infidelity. investment applies also. With a greater shift in Sexual infidelity involves having sex with some- women entering the workforce now, married/ one other than your primary partner, while emo- partnered women of higher SES may be tional infidelity involves falling in love or experiencing greater dissatisfaction than those diverting resources such as time investment, married/partnered women of lower SES or mar- attention, and emotional support to someone ried women of previous generations because the other than the primary partner (Shackelford et al. transition to parenthood may be more pro- 2004; Shackelford and Buss 1997). While both nounced. Also, with more women working now, types of infidelity can be distressing, a sex Sexual Conflict After Conception 5 difference emerges for reactions to infidelity partner, it would be especially advantageous for dependent upon the type of infidelity committed. a man to use heightened mate retention and mate- For men, if a woman is adulterous, it threatens his guarding tactics due to an overestimation that the paternity certainty and opens the possibility of partner would commit sexual infidelity. A man him being cuckolded into raising offspring that with a pregnant partner could experience repro- would not contribute to furthering his genetic line. ductive losses if he underestimates his pregnant This potential risk causes men to be more upset by partner’s potential for sexual infidelity. Each of sexual infidelity compared to emotional infidelity these situations could cause conflict among the (Buss et al. 1992). couple because the mate-guarding tactics utilized For women, a male partner who commits emo- by the man could become too controlling, or they tional infidelity signals a loss of investment in the could become not controlling enough to guard couple’s offspring since some of the man’s time against a loss. and resources are diverted to another woman and possibly to this other woman’s offspring. Thus, women are more upset by a partner’s commission Child Custody and Child Support of emotional infidelity. So, the jealousy each sex Conflict experiences most is dependent on the type of infidelity their partner commits (Wiederman and Shackelford and Buss (1997) explain that marital Kendall 1999). This differential jealousy adapta- satisfaction is an adaptive function because it tion helps to ensure one’s own fitness (Bendixen allows the couple to realize it is time for them to et al. 2015). find a different partner. If the couple decides to Researchers have discovered that during preg- dissolve their relationship, and they have children, nancy, men are more likely to commit infidelity conflict can arise. (Whisman et al. 2007). This may occur because Since, the individuals are no longer living there are reproductive advantages gained by hav- together, one of the individuals must help provide ing extra-pair copulations. If a man has multiple for the child. Consistent with parental investment partners that he reproduces with, then his fitness is theory (Trivers 1972), usually women are the ones increased, and his genetic legacy is likely to con- in heterosexual relationships to gain custody of tinue. But, getting caught cheating on a partner the child (Anderson 2011; Grall 2007). Men’s can cause a high level of conflict, leading to mate largest investment is financial which can lead to expulsion, depending on the type of infidelity conflict after relationship dissolution. committed (Shackelford et al. 2002). In 2011 the US Census Bureau estimated that Since men are likely to commit infidelity when $37.9 billion dollars in child support was owed a woman is pregnant, conflict may arise in the during the year of 2011, and 53.4% were single couple such that women engage in more mate mothers (U.S. Census Bureau 2013). This statis- guarding. This would be adaptive since sexual tics suggests that men are being forced to pay their infidelity on the part of her male partner could ex-wives money to help provide for their child. lead to a loss of investment in her offspring. Not Research speculates that although it may be surprisingly, Graham-Kevan and Archer (2009) advantageous for men to invest in their child, report that pregnant women do engage in more even if they are not living with them, it may also mate guarding than nonpregnant women. benefit them in not supporting the child Conception may lead to conflict based in error (Shackelford et al. 2005). Men may refuse or management theory (EMT) because Buss (2001) want to reduce their payments of child support, reports that inferential biases are made about because if they are giving money to an ex-partner potential infidelity. From an EMT perspective, they do not have 100% certainty that the money is there are costs and benefits associated with over- going to their offspring and not to their ex-partner estimating the potential for sexual infidelity. So, in or their ex-partner’s new partner. If this occurs, certain contexts, as in the case of a pregnant then the man is ultimately decreasing his fitness 6 Sexual Conflict After Conception by giving up resources to an individual that is not Buss, D. M. (2001). Cognitive biases and emotional his mate. A man may also want to reduce or not wisdom in the evolution of conflict between the sexes. Current Directions in Psychological Science, pay his child support if he has a new partner, since 10(6), 219–223. women tend to prefer men who are good financial Buss, D. M., Larsen, R. J., Westen, D., & Semmelroth, J. providers (Buss 1989). Men may want to divert (1992). Sex differences in jealousy: Evolution, physi- funds away from their child support and use those ology, and psychology. Psychological Science, 3, 251–255. funds to attract a new mate, which will ultimately Buss, D. M., & Schmitt, D. P. (1993). Sexual strategies increase his fitness. This can create conflict among theory: An evolutionary perspective on human mating. the man and the mother of his child requesting the Psychological Review, 100(2), 204. child support. The aforementioned research Buss, D. M., & Duntley, J. D. (2011). The evolution of intimate partner violence. and Violent shows that evolutionary theory can explain sexual Behavior, 16(5), 411–419. conflict after conception occurs. Cox, M. J., Paley, B., Burchinal, M., & Payne, C. C. (1999). Marital perceptions and interactions across the transition to parenthood. Journal of Marriage and the Family, 61,611–625. References Daly, M., & Wilson, M. I. (1982). Whom are newborn babies said to resemble? Ethology and Sociobiology, 3(2), 69–78. Abdool, Z., Thakar, R., & Sultan, A. H. (2009). Postpartum Deacy, S., & McHardy, F. (2013). Uxoricide in pregnancy: female sexual function. European Journal of Obstetrics Ancient Greek in evolutionary per- & Gynecology and Reproductive Biology, spective. , 11(5), 994–101. 145(2), 133–137. https://doi.org/10.1177/147470491301100505. Anderson, K. (2006). How well does paternity confidence Doss, B. D., Rhoades, G. K., Stanley, S. M., & match actual paternity? Current Anthropology, Markman, H. J. (2009). The effect of the transition to 47(3), 513–520. parenthood on relationship quality: An 8-year prospec- Anderson, K,G. (2011). Does paying child support reduce tive study. Journal of Personality and Social Psychol- men's subsequent marriage and fertility? Evolution and ogy, 96(3), 601. Human Behavior, 32(2), 90–96 Doss, B. D., & Rhoades, G. K. (2017). The transition to Apicella, C. L., & Marlowe, F. W. (2004). Perceived mate parenthood: Impact on couples’ romantic relationships. fidelity and paternal resemblance predict men's invest- Current Opinion in Psychology, 13,25–28. ment in children. Evolution and Human Behavior, Escasa-Dorne, M., Young, S., & Gray, P. B. (2013). Peri- 25(6), 371–378. partum shifts in female . In M. Fisher, Belsky, J., Spanier, G. B., & Rovine, M. (1983). Stability J. R. Garcia, & R. S. Chang (Eds.), Evolution’s and change in marriage across the transition to parent- empress: Darwinian perspectives on the nature of hood. Journal of Marriage and the Family, 567–577. women. New York: Oxford University Press. Bendixen, M., Kennair, L. E. O., & Buss, D. M. (2015). Feldman, R., Weller, A., Zagoory-Sharon, O., & Levine, A. Jealousy: Evidence of strong sex differences using both (2007). Evidence for a neuroendocrinological founda- forced choice and continuous measure paradigms. Per- tion of human affiliation plasma oxytocin levels across sonality and Individual Differences, 86, 212–216. pregnancy and the postpartum period predict mother- Betzig, L. (1989). Causes of conjugal dissolution: A cross- infant bonding. Psychological Science, cultural study. Current Anthropology, 30(5), 654–676. 18(11), 965–970. Brewis, A., & Meyer, M. (2005). Marital coitus across the Fisher, H. E. (1989). Evolution of human serial pair bond- life course. Journal of Biosocial Science, ing. American Journal of Physical Anthropology, 37(04), 499–518. 78(3), 331–354. Burch, R. L., & Gallup, G. G., Jr. (2000). Perceptions of Friedman, B. X., & Shackelford, T. K. (1999, June). paternal resemblance predict family violence. Evolu- Re-allocation of mating effort as a result of pregnancy. tion and Human Behavior, 21, 429–435. Paper presented at the annual meeting of the human Burch, R. L., & Gallup, G. G., Jr. (2004). Pregnancy as a behavior and evolution society, Salt Lake City, Utah. stimulus for domestic violence. Journal of Family Vio- Frum, D. (2000). How we got here: The 70’s: The decade lence, 19(4), 243–247. that brought you modern life (for better or worse). Buss, D. M. (1989a). Sex differences in human mate pref- New York: Basic Books. erences: Evolutionary hypotheses tested in 37 cultures. Galbally, M., Lewis, A. J., IJzendoorn, M. V., & Behavioral and Brain Sciences, 12(1), 1–14. Permezel, M. (2011). The role of oxytocin in mother- Buss, D. M. (1989b). Conflict between the sexes: Strategic infant relations: A systematic review of human studies. interference and the evocation of anger and upset. Harvard Review of Psychiatry, 19(1), 1–14. Journal of Personality and Social Psychology, 56(5), 735. Sexual Conflict After Conception 7

Gazmararian, J. A., Lazorick, S., Spitz, A. M., McFarlane, J., Campbell, J. C., Sharps, P., & Watson, K. Ballard, T. J., Saltzman, L. E., & Marks, J. S. (1996). (2002). Abuse during pregnancy and femicide: Urgent Prevalence of violence against pregnant women. Jour- implications for women’s health. Obstetrics & Gyne- nal of the American Medical Association, cology, 100(1), 27–36. 275(24), 1915–1920. McKibbin, W. F., Goetz, A. T., Shackelford, T. K., Gjerdingen, D. K., & Chaloner, K. (1994). Mothers’ expe- Schipper, L. D., Starratt, V. G., & Stewart-Williams, rience with household roles and social support during S. (2007). Why do men insult their intimate partners? the first postpartum year. Women & Health, Personality and Individual Differences, 21(4), 57–74. 43(2), 231–241. Graham-Kevan, N., & Archer, J. (2009). Control tactics Myrskylä, M., & Margolis, R. (2014). Happiness: Before and partner violence in heterosexual relationships. Evo- and after the kids. Demography, 51(5), 1843–1866. lution and Human Behavior, 30(6), 445–452. Nomaguchi, K. M., & Milkie, M. A. (2003). Costs and Grall, T. (2007). Custodial mothers and fathers and their rewards of children: The effects of becoming a parent child support: 2005: Current population reports.US on adults’ lives. Journal of Marriage and Family, Census Bureau, pp 60–234. 65(2), 356–374. Gray, P. B., Kahlenberg, S. M., Barrett, E. S., Lipson, S. F., Platek, S. M., Burch, R. L., Panyavin, I. S., & Ellison, P. T. (2002). Marriage and fatherhood are Wasserman, B. H., & Gallup, G. G. (2002). Reactions associated with lower testosterone in males. Evolution to children’s faces: Resemblance affects males more and Human Behavior, 23(3), 193–201. than females. Evolution and Human Behavior, Gray, P. B., & Crittenden, A. N. (2014). Father Darwin: 23(3), 159–166. Effects of children on men, viewed from an evolution- Platek, S. M., Critton, S. R., Burch, R. L., Frederick, D. A., ary perspective. Fathering, 12(2), 121–142. Myers, T. E., & Gallup, G. G. (2003). How much Gray, P. B., Reece, J. A., Coore-Desai, C., Dinnall- paternal resemblance is enough? Sex differences in Johnson, T., Pellington, S., & Samms-Vaughan, M. hypothetical investment decisions but not in the detec- (2015). Sexuality among fathers of newborns in tion of resemblance. Evolution and Human Behavior, Jamaica. BMC Pregnancy and Childbirth, 15, 44. 24(2), 81–87. Groves, A. K., Moodley, D., McNaughton-Reyes, L., Mar- Platek, S. M., Raines, D. M., Gallup, G. G., tin, S. L., Foshee, V., & Maman, S. (2015). Prevalence, Mohamed, F. B., Thomson, J. W., Myers, T. E & rates and correlates of intimate partner violence among Arigo, D. R. (2004). Reactions to children’s faces: south African women during pregnancy and the post- Males are more affected by resemblance than females partum period. Maternal and Child Health Journal, are, and so are their brains. Evolution and Human 19(3), 487–495. Behavior, 25(6), 394–405. Hellmuth, J. C., Gordon, K. C., Stuart, G. L., & Sales, P., & Murphy, S. (2000). Surviving violence: Preg- Moore, T. M. (2013). Risk factors for intimate partner nancy and drug use. Journal of Drug Issues, violence during pregnancy and postpartum. Archives of 30, 695–724. Women's Mental Health, 16(1), 19–27. Shackelford, T. K., & Buss, D. M. (1997). Marital satis- Kurdek, L. A. (1999). The nature and predictors of the faction in evolutionary psychological perspective. In trajectory of change in marital quality for husbands Satisfaction in close relationships (pp. 7–25). and wives over the first 10 years of marriage. Develop- New York: Guilford Press. mental Psychology, 35(5), 1283. Shackelford, T. K., Buss, D. M., & Bennett, K. (2002). Kuhle, B. X. (2011). Did you have sex with him? Do you Forgiveness or breakup: Sex differences in responses to love her? An in vivo test of sex differences in jealous a partner's infidelity. Cognition & Emotion, interrogations. Personality and Individual Differences, 16(2), 299–307. 51(8), 1044–1047. Shackelford, T. K., & Goetz, A. T. (2007). Adaptation to Long, E. C. J., Cate, R. M., Fehsenfeld, D. A., & sperm competition in humans. Current Directions in Williams, K. M. (1996). A longitudinal assessment of Psychological Science, 16(1), 47–50. a measure of premarital sexual conflict. Family Rela- Shackelford, T. K., Voracek, M., Schmitt, D. P., tions, 45, 302–308. Buss, D. M., Weekes-Shackelford, V. A., & Lucas, T., Parkhill, M. R., Wendorf, C. A., Michalski, R. L. (2004). Romantic jealousy in early Imamoglu, E. O., Weisfeld, C. C., Weisfeld, G. E., & adulthood and in later life. Human Nature, Shen, J. (2008). Cultural and evolutionary components 15(3), 283–300. of marital satisfaction: A multidimensional assessment Shackelford, T. K., Weekes-Shackelford, V. A., & of measurement invariance. Journal of Cross-Cultural Schmitt, D. P. (2005). An evolutionary perspective on Psychology, 39(1), 109–123. why men refuse or reduce their child support payments. Martin, S. L., Harris-Brit, A., Li, Y., Moracco, K. E., Basic and Applied Social Psychology, 27, 297–306. Kupper, L. L., & Campbell, J. C. (2004). Changes in Shotland, R. L., & Goodstein, L. (1992). Sexual prece- intimate partner violence during pregnancy. Journal of dence reduces the perceived legitimacy of sexual Family Violence, 19, 201–210. refusal: An examination of attributions concerning 8 Sexual Conflict After Conception

date and consensual sex. Personality and Social U.S. Census Bureau. (2013, October). Custodial mothers Psychology Bulletin, 18(6), 756–764. and fathers and their child support: 2011. Retrieved Sprecher, S., & Cate, R. M. (2004). Sexual satisfaction and from: http://www.census.gov/people/childsupport/ sexual expression as predictors of relationship satisfac- Valladares, E., Peña, R., Persson, L. A., & Högberg, U. tion and stability. In J. H. Harvey, A. Wenzel, & (2005). Violence against pregnant women: Prevalence S. Sprecher (Eds.), The handbook of sexuality in close and characteristics. A population-based study in Nica- relationships (pp. 235–256). New York: Lawrence ragua. BJOG, 112, 1243–1248. Erlbaum Associates. von Sydow, K. (1999). Sexuality during pregnancy and Trivers, R. (1972). Parental investment and sexual selec- after childbirth: A metacontent analysis of 59 studies. tion (Vol. 136, p. 179). Cambridge: Biological Labora- Journal of Psychosomatic Research, 47(1), 27–49. tories, Harvard University. Wiederman, M. W., & Kendall, E. (1999). Evolution, sex, Twenge, J. M., Campbell, W. K., & Foster, C. A. (2003). and jealousy: Investigation with a sample from Swe- Parenthood and marital satisfaction: A meta-analytic den. Evolution and Human Behavior, 20(2), 121–128. review. Journal of Marriage and Family, 65(3), Whisman, M. A., Gordon, K. C., & Chatav, Y. (2007). 574–583. Predicting sexual infidelity in a population-based sam- ple of married individuals. Journal of Family Psychol- ogy, 21, 320–324.