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416 BritishJournalofPsychology(2017),108,416–435 ©2016TheBritishPsychologicalSociety www.wileyonlinelibrary.com Altruism predicts mating success in humans Steven Arnocky1*, Tina Pich(cid:1)e1, Graham Albert1, Danielle Ouellette1 and Pat Barclay2 1DepartmentofPsychology,NipissingUniversity,NorthBay,Ontario,Canada 2DepartmentofPsychology,UniversityofGuelph,Canada Inorderfornon-kinaltruismtoevolve,altruistsmustreceivefitnessbenefitsfortheir actions that outweigh thecosts.Several researchers havesuggested that altruism isa costlysignalofdesirablequalities,suchthatitcouldhaveevolvedbysexualselection.In two studies, we show that altruism is broadly linked with mating success. In Study 1, participantswhoscoredhigheronaself-reportaltruismmeasurereportedtheywere moredesirabletotheoppositesex,aswellasreportedhavingmoresexpartners,more casualsexpartners,andhavingsexmoreoftenwithinrelationships.Sexmoderatedsome oftheserelationships,suchthataltruismmatteredmoreformen’snumberoflifetimeand casual sex partners. In Study 2, participants who were willing to donate potential monetarywinnings(inamodifieddictatordilemma)reportedhavingmorelifetimesex partners,morecasualsexpartners,andmoresexpartnersoverthepastyear.Menwho werewillingtodonatealsoreportedhavingmorelifetimedatingpartners.Furthermore, thesepatternspersisted,evenwhencontrollingfornarcissism,BigFivepersonalitytraits, andsociallydesirableresponding.Theseresultssuggestthataltruistshavehighermating successthannon-altruistsandsupportthehypothesisthataltruismisasexuallyselected costlysignalofdifficult-to-observequalities. Altruistic behaviours1 have been observed across diverse vertebrate species of birds (Krams, Krama, Igaune, & M€and, 2008), fish (Bshary, 2002),amphibians(To(cid:1)th,Hoy, & Hettyey,2011),reptiles(Sinervoet al.,2006),andmammals(Wilkinson,1988),including modern humans (Trivers, 1971). Early research on altruistic behaviour among non-kin centred upon Trivers’ (1971) theory of reciprocity – the notion that individuals may behave selflessly to receive some benefit in the future. However, researchers have recently suggested that reciprocity alone cannot sufficiently account for all altruistic behaviours among unrelated individuals (Fehr & Fischbacher, 2003; Sober & Wilson, 1998;reviewedbyBarclay&VanVugt,2015).Ithasbeenfurtherarguedthatreciprocity mightonlyevolveundercircumscribedenvironmentalconditions(Roberts,1998).This haspromptedresearcherstoconsideradditionalfactors,whichmayhavecontributedto theevolutionofaltruisticbehaviour. Onehypothesis,whichhasgainedrecentempiricalsupportfromstudiesonhuman behaviour,isthepossibilitythataltruismfunctionsasacostlysignalofqualitiesthatare *CorrespondenceshouldbeaddressedtoStevenArnocky,DepartmentofPsychology,NipissingUniversity,100CollegeDrive, NorthBay,ON,CanadaP1B8L7(email:[email protected]). 1By‘altruism’,wemeanactsthatdecreasesomefitness-proxyintheactor(atleasttemporarily)andfunctiontoconferbenefits onarecipient,regardlessoftheunderlyingpsychologicalmotivations.Thosewhodefine‘altruism’differentlyshouldsubstitute theirpreferredtermforsuchphenomena. DOI:10.1111/bjop.12208 Altruismandmatingsuccess 417 otherwise difficult to observe (Gintis, Smith, & Bowles, 2001; Zahavi, 1975). For example,huntingandsharinglargegame–especiallywithoutexpectationofreciprocity –demonstrateone’sskillsasagoodhunterandthusone’svalueasanallyormate(Jaeggi & Gurven, 2013; Smith & Bliege Bird, 2000). In particular, it can be valuable to signal desirablequalitiestopotentialmates.Insupportofthis,evidencesuggeststhataltruists maybeviewedbyothersasmoreattractivematingpartnersrelativetothosewhoareless altruistic (Barclay, 2010; Farrelly, Lazarus, & Roberts, 2007; Moore et al., 2013; Oda, Okuda,Takeda,&Hiraishi,2014;Phillips,Barnard,Ferguson,&Reader,2008).Yetsuch studies on preferences for altruistic mates fall short of determining whether altruism does indeed confer a mating advantage to the altruist. Given that mate preferences are notalwaysgoodindicatorsofactualmatechoice(Todd,Penke,Fasolo,&Lenton,2007), thegoalofthisstudywastoexplorewhetherself-reportedaltruisticbehaviourpredicted individuals’ mating behaviour in terms of their self-reported mating success, their lifetime number of sex partners, their lifetime number of casual sex partners, and the frequency with which they copulate with their current romantic partner and whether these relationships vary as a functionof sex. Costlysignalling Acostlysignalisanymorphologicalorbehaviouraltraitwhichadvertisesanorganism’s qualityatsomeexpense(Zahavi,1975;Zahavi&Zahavi,2007).Providedthatthesignal is sufficiently costly for those who do not actually possess the quality (Getty, 2006; Sz(cid:1)amado(cid:1),2011),bearingtheburdenofthatfeaturecanserveasanhonestreflectionof thesignaller’squalityorcooperativeintent(Barclay&Reeve,2012;Gintiset al.,2001). By attending to such signals, observers gain useful information about the qualities of the signaller(s). Someresearchershaveconceptualizedaltruismwithinthisframeworkasacourtship display which can advertise one’s mate-value characteristics including genetic endow- ment,health,resourcecontrol,orvigour(Miller,2000,2007;Smith&BliegeBird,2000; Tessman,1995).Totheextentthataltruismisdesiredbypotentialmatingpartners,itis widelypresumedthatanassociatedincreaseinmatingsuccesswouldservetorecoupthe initialcostofthealtruisticactsordisposition(Hardy&VanVugt,2006).Insupportofthe costly signalling hypothesis, McAndrew and Perilloux (2012) showed that individuals indeedviewothers’altruisticbehaviourasbeingcostly,challenging,andimportant.The potentialutilityofaltruismasacostlysignalofphenotypicqualityorcooperativeintent mayleadindividualstoattempttooutcompeterivalswithinthisdomain–aphenomena termed ‘competitive altruism’ (Barclay, 2011, 2013; Roberts, 1998). Barclay and Willer (2007) found that when observers could choose whom to associate with, participants competedtobemoregenerousthanothers.Giventheparticularimportanceofsuccessful intrasexual competition towards augmenting male reproductive potential (Bateman, 1948),suchcompetitivealtruismmaybemoreprevalentamongmenrelativetowomen. Multiple studies have shown that men are more generous when observed by women, whereasthereverseisoftennottrue(Bo€hm&Regner,2013;Tognetti,Berticat,Raymond, &Faurie, 2012;Van Vugt&Iredale,2013).McAndrewandPerilloux(2012)found that groups containing multiple males evidenced more competition to become an altruist relativetogroupscontainingmultiplefemales(Bo€hm&Regner,2013;Hardy&VanVugt, 2006;Iredale,VanVugt,&Dunbar,2008).Similarly,RaihaniandSmith(2015)foundthat men make more online charitable donations to attractive women than to unattractive womenandwillcompetewithothermenoverdonationstowomen. 418 StevenArnockyet al. Dowepreferaltruisticmates? Empiricaltestsofaltruismasastrategyforaccessingmatingopportunitieshavehitherto focussedonindividuals’penchantsforaltruisticmates.Forexample,Phillipset al.(2008) assessedmen’sandwomen’sstatedpreferencesforaltruistictraitsinalong-termmating partner(boyfriend,girlfriend,husband,orwife).Resultsshowedthatwomenexhibiteda strongerpreferenceforaltruistictraitsinaprospectiveromanticpartnerrelativetomen, controllingforrelationshiplengthandsocialdesirabilityscores.Farrelly(2011)andOda et al.(2014)havealsodemonstratedthatwomenpreferaltruisticbehavioursinpotential long-termmates;apreferencethatwasnotaffectedbywomen’sovulatorycycle.Barclay (2010)askedyoungmenandwomentoreadfictitiousdatingadvertisementsofopposite sexindividualsforshort-andlong-termrelationships,whichvariedintheexpressionof altruistic tendencies. Participants rated the ads on their interest in pursuing various relationshipswiththatindividual,aswellasonthetarget’sattractivenessandpersonality characteristics. Barclay (2010) found that both men and women rated individuals with altruistic traits as desirable for a long-term relationship, whereas women but not men ratedaltruisticopposite-sexindividualsasdesirableforsingledates(thiscouldbeshort- term mating, but it is important to note that desirability for one-night stands was unaffected).Takentogether, the results ofpreviousresearch suggestthat altruismmay benefitbothmen’sandwomen’sdesirability,especiallyasalong-termmate.Itiscurrently ambiguouswhetheraltruismaffectsone’sdesirabilityasashort-termpartner,withsome studies saying no (Barclay, 2010; Oda et al., 2014), and other studies suggesting that altruistic men are more desirable short-term partners than non-altruistic men (Farrelly, Clemson,&Guthrie,2016;Mooreet al.,2013). Interestingly, both altruistic personality and individuals’ preferences for altruistic matesappeartobeatleastpartlyheritable,asevidencedbygreaterconcordanceofthese factorsamongmonozygotictwinscomparedtodyzygotictwins,withgenesaccounting for much of the variance in the relationship (Phillips, Ferguson, & Rijsdijk, 2010). Accordingly,Phillipset al.(2010)predictedthatinancestralpopulations,altruistswould havematedfrequentlywithindividualswhoexhibitedapreferenceforhavinganaltruistic partner. Studies of individuals’ stated preferences for altruistic mates are nevertheless limited in the conclusions that can be drawn from them regarding the evolution of altruismasamatingstrategy.Giventhatmatepreferencesareoneamongahostoffactors, including the availability of mates and resources and the presence of competitors that determineactualmatingdecisionsandbehaviours(Arnocky,Ribout,Mirza,&Knack, 2014; Arnocky, Sunderani, & Vaillancourt, 2013; Todd et al., 2007), it remains unclear whetherornotaltruisticbehaviourisindeedcorrelatedwithenhancedmatingsuccess. Thisisanimportantdistinction,giventhatitisactualmatingoutcomeswhichultimately contributetotheevolutionofparticularphenotypes(Zohar&Guttman,1989).Therefore, to the extent that mating with an altruist confers some reproductive advantage, or has done so over the course of human evolutionary history, we would expect altruists to exhibitincreasedmatingsuccessrelativetotheirlessaltruisticcounterparts. Indirect evidence (typically from hunter-gatherer populations) lends circumstantial support to this hypothesis. It has been found that successful male hunters (who often share the meat they have obtained) receive greater reproductive access to females (Hawkes,1991;Hawkes,O’Connell,Hill,&Charnov,1985;Hill&Hurtado,1996;Hill& Kaplan,1988).Thisevidenceseemsconsistentwithsexualselectionfavouringaltruists (Gintiset al.,2001;Gurven&vonRueden,2006).Tognetti,Berticat,Faurie,andRaymond (2014) found that rural Senegalese marry assortatively on cooperativeness, such that cooperative men tend to marry cooperative women. However, such assortment alone Altruismandmatingsuccess 419 could reflect either cooperators being highly desirable and choosing each other or cooperatorsbeingundesirableandmarryingeachotherasa‘lastresort’(e.g.,cooperation as compensation for low mate value, Barclay, 2013, 2016). It is therefore essential to expandupontheseinitialfindingsbyexplicitlymeasuringaltruisminrelationtomating success,whichcanbedoneamongyoungadultsinacontemporaryindustrializedculture. Acrosstwostudies,wetestedthehypothesisofaltruismasacostlysignalbyexamining whether self-reported altruism (Study 1) and observable altruism in terms of monetary donation(Study2)predictedvariousmatingsuccessindicesinsamplesofundergraduate menandwomen.Rhodes,Simmons,andPeters(2005)suggestmatingsuccessintheway of sexual behaviour is a sufficient index of reproductive success in ancestral times; however, modern-day contraception attenuates this link between mating success translatingintoreproductivesuccess. STUDY1 We hypothesized that self-reported altruism would predict greater self-reported desirability as a mate, having had more lifetime sex partners, more lifetime casual sex partners,andamongthosecurrentlyinacommittedromanticrelationship,morefrequent copulation with one’s partner within the past 30 days. Moreover, given that some researchhassuggestedthataltruismmaybemoreimportantasacostlysignalamongmen (especiallyforshort-termmatings,seeBarclay,2010;Bo€hm&Regner,2013;Farrellyet al., 2016;Mooreet al.,2013;Raihani&Smith,2015;VanVugt&Iredale,2013),weexplored interactioneffectsofsexasapotentialmoderatortotheserelationships.Thesehypotheses weretestedinconsiderationofapotentialconfoundingaspectofpersonality.Specifically, itispossiblethatanyrelationshipsbetweenaltruismandmatingsuccessmaybeanartefact ofBigFivepersonalitydimensions,whichhavebeenshowncross-culturallytocorrelate with altruism (Johnson et al., 1989). For example, extraversion has been consistently linkedtoincreasedsexualbehaviouracrossmany(butnotall)worldregions(Schenk& Pfrang, 1986; Schmitt, 2004). Participant age was also controlled for given previous associationswithnumberofsexpartnersinuniversitysamples(Arnockyet al.,2013). Method Participants Our sample consisted of 192 unmarried women and 105 unmarried men living in NorthernOntario,Canada,betweentheagesof16and33(M = 21.21,SD = 3.48).The age ethniccompositionofthesamplewasasfollows:Caucasian(90%),Aboriginal(4%),Black (3%),Asian(2%),andSouthAsian(1%).Participantswererecruitedincommonareasofa smalluniversityandcollege.Asapartofalargerstudyonhumanmatingbehaviour,each participant completed a paper-and-pencil-based questionnaire containing self-report measures of altruistic behaviour, personality, mating success, and sexual history. Participantswerecompensatedwithanopportunitytowinoneofthree$100draws. Materialsandprocedure Altruism The 20-item Self-report Altruism Scale was used to measure dispositional altruism (Rushton, Chrisjohn, & Fekken, 1981). This is a widely used measure, which was 420 StevenArnockyet al. developedinthesameProvinceofCanadainwhichthecurrentresearchtookplace.The measure consists of items that assess the frequency of altruistic acts towards others, wherebydirectreciprocitywouldbeunlikelyorunexpected.Exampleitemsincludethe following:‘Ihavegivenmoneytoacharity’,‘Ihavehelpedpushastranger’scaroutofthe snow’,‘Ihavegivendirectionstoastranger’,‘Ihavedonatedblood’,‘Ihaveofferedtohelp ahandicappedorelderlystrangeracrossastreet’,and‘IhavehelpedaclassmatewhoIdid notknowthatwellwithanassignmentwhenmyknowledgewasgreaterthanhisorhers’. Responseoptionsrangingalonga5-pointLikert-typescale(0 = Never,4 = VeryOften). The measure showed good internal consistency in both men (a = .86) and women (a = .87).Anexploratoryfactoranalysiswasconductedtodeterminethefitoftheitemsto one fixed factor: all items loaded well on a single factor, and there were no major differencesintherelationshipbetweenaltruismandmatingsuccessindicesatthesingle- itemlevel(seeSupportinginformation). Self-reportedmatingsuccess Self-reporteddesirabilitytotheoppositesexwasassessedusingtheself-perceivedmating success scale (SPMS; Landolt, Lalumi(cid:3)ere, & Quinsey, 1995). The measure consists of 8 items with response options ranging along a 7-point Likert-type scale (1 = disagree, 7 = agree).Theitemsareasfollows:‘MembersoftheoppositesexthatIlike,tendtolike meback’,‘Membersoftheoppositesexnoticeme’,‘Ireceivemanycomplimentsfrom membersoftheoppositesex’,‘Membersoftheoppositesexarenotveryattractedtome’ (reverse scored), ‘I receive sexual invitations from members of the opposite sex’, ‘Membersoftheoppositesexareattractedtome’,‘IcanhaveasmanysexualpartnersasI choose’, and ‘I do not receive many compliments from members of the opposite sex’ (reversescored).Themeasureshowedgoodinternalconsistency(a = .85). Matingsuccessindices(sexualhistoryvariables) Inassessingparticipants’pastsexualbehaviours,respondentsself-reportedon(1)their numberofconsensuallifetimesexpartnersand(2)theirnumberofconsensualcasualsex partnerswherecasualsexwasdefinedas‘asexualpartnerwho[participants]wereNOT inanexclusive,committedrelationshipwith’(Arnockyet al.,2013).Finally,participants whoself-reportedasbeingcurrentlyinaromanticrelationship(foratleast1 month)and whoreportedhavinghadsexwiththeircurrentpartneratleastonceindicatedthenumber oftimestheyhadengagedinconsensualsexualintercourseoverthepast30 dayswiththat partner,asameasureofsexualaccesswithintheromanticdyad.Ofthetotalsample,111 participants(37.4%)metthecriteriaforcurrentlybeinginaromanticrelationshipwitha personwhomtheyhadpreviouslycopulatedwith(47men,64women). Personalitydimensions BigFivepersonalitydimensionsweremeasuredusingtheTen-ItemPersonalityInventory (TIPI; Gosling, Rentfrow, & Swann, 2003). Participants read the following set of instructions:‘Hereareanumberofpersonalitytraitsthatmayormaynotapplytoyou. Pleasewriteanumbernexttoeachstatementtoindicatetheextenttowhichyouagreeor disagreewiththatstatement.Youshouldratetheextenttowhichthepairoftraitsapplies toyou,evenifonecharacteristicappliesmorestronglythantheother’.Participantsthen reported on the following ten items using a 7-point Likert-type scale (1 = disagree Altruismandmatingsuccess 421 strongly, 7 = agree strongly). Example items include the following: ‘Extraverted, enthusiastic’, and ‘Reserved, quiet’ (reverse scored) comprising the extraversion subscale. The TIPI has shown to converge with self, observer, and peer ratings of personality, as well as good construct validity and test–retest reliability (Gosling et al., 2003; Jonason, Teicher, &Schmitt, 2011).In this study,the subscalesall showed good intercorrelation,r = .22,p < .001–.52,p < .001.Alloftheanalysesofaltruismproduce qualitativelysimilarresultswhetherageandpersonalityareincludedorexcludedinthe regressionmodels(Table 1). Statisticalanalysis MultipleordinaryleastsquaresregressionanalyseswereconductedusingthePROCESS macro for SPSS (Hayes, 2013). Variables were mean centred (for continuous variables: altruism,age,extraversion,lifetimesexpartners,lifetimecasualsexpartners,andmating success) and dummy coded (for dichotomous variable sex, M = (cid:1)1, F = 1). Altruistic behaviour,sex(asthemoderatingvariable)andtheirinteractionwerecalculatedwithage andBigFivepersonalitytraitsenteredascovariatesforeachofthefourmatingsuccess outcomes:self-reportedmatingsuccess,lifetimenumberofsexpartners,lifetimenumber of casual sex partners, and (for romantically involved participants) number of partner copulations in the past 30 days. Following the rationale outlined by Hayes (n.d.), we present unstandardized regression coefficients and standardized t-scores for each relationship(correlationsbetweenaltruismandmatingsuccessindicesarepresentedin theSupporting information).Wepresenttheeffects ofaltruismbothwithandwithout covariates(ageandpersonalityfactors). ResultsandDiscussion Wefirstexaminedtherelationshipbetweenaltruism,sex,andparticipants’self-reported mating success, controlling for age and TIPI scores (Table 1). Results showed that altruistic behaviour significantly predicted self-reported mating success, b = 0.52, p = .0002.Sexwasnotrelatedtoself-reportedmatingsuccess,b = (cid:1)0.04,p = .61.The altruism 9 sex interaction was non-significant, suggesting that altruism predicts self- reportedmatingsuccess regardless ofsex,b = 0.19,p = .16.Themodelaccountedfor 19%(R2 = .19)ofexplainedvarianceinindividuals’self-reportedmatingsuccess. Wenextexaminedtherelationshipbetweenaltruism,sex,andlifetimenumberofsex partners (Table 1). Results revealed that altruistic behaviour significantly predicted lifetimenumberofsexpartners,b = 2.60,p = .007(Figure 1).Sexalsopredictedlifetime number of sex partners, b = (cid:1)1.50, p = .02, suggesting that men report having more lifetime sex partners than women. Moreover, the altruism 9 sex interaction was also significant,b = (cid:1)3.01,p = .002,suggestingthataltruismmattersmoreformen’saccess tosexpartnersrelativetowomen.Simpleslopesanalysisindeedindicatedthataltruism predictedlifetimenumberofsexpartnersformen,b = 6.34,b = .40,p = .0001,butnot for women, b = 0.76, b = .02, p = .57. The model accounted for 26% (R2 = .26) of explainedvarianceinindividuals’totalnumberoflifetimesexpartners. Inexaminingindividuals’lifetimenumberofcasualsexpartners,itwassimilarlyfound that altruistic behaviour significantly predicted total number of casual sex partners, b = 2.16,p = .009(Table 1).Sexpredicted numberofcasualsexpartners,b = (cid:1)1.38, p = .009,suggestingthatmenreportmorecasualsexpartnersthandidwomen.There 422 StevenArnockyet al. dices, ncy SE 1.690.921.660.230.600.770.650.850.77 1.370.740.12 n e i u s q atingsucces pulationfre b .27.02.21.03.08(cid:1).19.15.03(cid:1).03 .30(cid:1).02.15 m o c orof pair b †8312050741†36822217 26**1824 dict In- 3.0.3.0.0.(cid:1)1.0.0.(cid:1)0. 4.(cid:1)0.2. e r p a s 334334756 651 a s E 858134344 748 m er S 0.0.0.0.0.0.0.0.0. 0.0.0. s n estingaltrui ualsexpart b .16(cid:1).18(cid:1).22.21.21(cid:1).15(cid:1).07.01.01 .20(cid:1).19.23 t s s a el c d e ** * * formo Lifetim b 2.16**(cid:1)1.38**(cid:1)3.01**0.45**1.04**(cid:1)1.05*(cid:1)0.360.090.04 2.66**(cid:1)1.46**(cid:1)3.05** s r o r r e 728581334 558 d E 969135455 959 dar ers S 0.0.0.0.0.0.0.0.0. 0.0.0. n n andstaures) expart b .16(cid:1).17(cid:1).19.30.21(cid:1).13(cid:1).09.04(cid:1).01 .21(cid:1).18(cid:1).20 ncoefficientsonalitymeas Lifetimes b 2.60**(cid:1)1.50*(cid:1)3.01**0.75***1.30**(cid:1)1.10*(cid:1)0.570.35(cid:1)0.07 3.27***(cid:1)1.61**(cid:1)3.18** sioers sp Table1.Study1:Unstandardizedandstandardizedregrebothwithandwithoutcontrolvariables(ageandBigFive Self-reportmatingsuccess bbSE ModelwithcontrolvariablesAltruism0.52***.250.13=(cid:1)=(cid:1)(cid:1)Sex(M1,F1)0.04.040.099AltruismSex0.19.090.14Age0.09.030.02Extraversion0.28***.340.05Conscientiousness0.06.050.07Emotionalstability0.03.030.06(cid:1)(cid:1)Openness0.07.070.07(cid:1)(cid:1)Agreeableness0.05.050.07ModelwithoutcontrolvariablesAltruism0.55***.260.13(cid:1)(cid:1)Sex0.06.050.079AltruismSex0.18.080.13 †<*<**<***<Note.p.10;p.05;p.01;p.005. Altruismandmatingsuccess 423 Figure 1. Self-reportedaltruisminStudy1andreportedmatingsuccessofmales(dashedlines)and females(solidlines),asmeasuredby(a)scoresonascaleofself-reportedmatingsuccess,(b)numberof lifetimesexpartners,(c)numberofcasualsexpartners,and(d)numberofin-paircopulationsinthelast month.Participantsexmoderatestherelationshipbetweenaltruismandlifetimenumberofsexpartners andnumberofpast-yearsexpartners,butnotself-reportedmatingsuccessorlifetimecasualsex.Note. Fordisplaypurposes,lowaltruism = 1 SDbelowthemeanandhighaltruism = 1 SDabovethemean. [Colourfigurecanbeviewedatwileyonlinelibrary.com] was a significant altruism 9 sex interaction, b = (cid:1)3.01, p = .0004, suggesting that altruismrelated morestronglytonumberofcasualsexpartnersamongmenrelativeto women (Figure 1). Simple slopes analysis indeed indicated that altruism predicted lifetimenumberofsexpartnersformen,b = 5.88,b = .45,p = .0001,butnotforwomen, b = (cid:1)0.14, b = (cid:1).01, p = .89. The model accounted for 23% (R2 = .23) of explained varianceinindividuals’numberofcasualsexpartners. We next examined the relationship between altruism and number of times participantshadsexwiththeir partnerswithinthepast 30 daysamong asubset ofour sample who had a dating partner at the time of data collection (n = 111 participants, Table 1). Results showed that altruistic behaviour was modestly related to number of copulations in the past month, b = 3.83, p = .08. Sex did not predict number of copulations, b = 0.12, p = .90. The altruism 9 sex interaction was not significant, b = 3.05, p = .13. The model accounted for 13% (R2 = .13) of explained variance in individuals’in-paircopulations.Withoutthecontrolvariablesinthemodel,theeffectof altruismincreasedinsignificance,b = 4.26,p = .01. STUDY2 Study1showedalinkbetweenaltruismandmatingsuccessvariables.However,itwas limitedintheuseofaself-reportmeasureofaltruism.ForStudy2,weutilizedamodified 424 StevenArnockyet al. dictator dilemma as an observable measure of altruism, in which participants were enteredintoadrawfor$100andwereaskedtoindicatewhethertheywanted tokeep theirwinnings,ortohavetheresearchersdonateaspecificportionoftheirwinningson theirbehalftoaregisteredcharityoftheirchoosing. Study 2 also extended upon Study 1 by considering the potential role of social desirability bias in responding to altruistic and sexual history items. Research on the reporting ofsexual historieshas shown thatsocial desirabilitybias mightinfluencesex differencesinreportingnumberofsexpartners,wherebymentendtoover-report,and women to under-report, their number of past sexual partners (Fenton, Johnson, McManus, & Erens, 2001; Jonason, 2007). Research has also linked social desirability biastocharitablegiving(Lee&Sargeant,2011).Similarly,itisalsopossiblethatthosehigh innarcissism(grandiose,inflatedviewoftheself)mightengageinsomealtruisticactivities out of self-interest (Brunell, Tumblin, & Buelow, 2014) and narcissism also relates to differencesinmatingbehaviour,suchasinmoreshort-termmating(Jonason,Li,Webster, &Schmitt,2009).IftheresultsfromStudy1weredrivenbysociallydesirableresponding or by narcissists over-reporting their altruism, then any altruism-mating link should disappearwhencontrollingfornarcissismandsociallydesirableresponding. Thus,ourgoalwastodeterminewhetherobservablealtruismintheformofmonetary donationwouldpredictthesamematingsuccessvariablesasinStudy1,alongwithtwo additional mating success variables: total number of lifetime dating partners and total number of sex partners within the past year, while controlling for Big Five personality factors(assessedusingamorecomprehensivemeasure),narcissism,andsociallydesirable responding. Method Participants Our sample consisted of 335 undergraduate women and 189 undergraduate men from northernOntario,Canada,betweentheagesof18and47(M = 20.53,SD = 3.35).The age ethnic composition of the sample was largely Caucasian (94%). Participants were recruitedfromclassroomsatasmalluniversityandcollege.Participantcompletedapaper- and-pencil-based questionnaire containing self-report measures of personality, social desirabilityresponding,narcissism,matingsuccess,andsexualhistory.Participantswere compensatedwithanopportunitytowina$100drawandweregiventheopportunityto indicatewhethertheywouldliketobeawardedthewinningsortohavetheresearchers donateit(oraportion)toaregisteredcharityoftheirchoosing(ourbehaviouralmeasure ofaltruism). Altruism(monetarydonationtocharity) Participants completed a self-report survey after which they were told they would be entered into a draw for a chance to win $100 CAD. At the end of their questionnaire, participantsreadthefollowingstatement:‘Forcompletingthissurvey,yournamewillbe enteredintoa$100draw.Ifyouhappentowinthedraw,youmay(1)keepthemoney,(2) allowustodonatethemoneytoaregisteredcharityonyourbehalf,or(3)acombinationof thetwo.Ifyouwouldliketodonatetoaregisteredcharity,pleaseanswerthefollowing:I wouldliketheresearchertodonate$___________ofmywinningstothefollowingcharity on my behalf (any money not donated will be given to you the participant and can be Altruismandmatingsuccess 425 picked up at the Evolution Lab A-222H upon notification of winning the draw)’. Participants opting to donate had the option of World Wildlife Foundation Canada, CanadianCancerSociety,ALSSocietyofCanada,CanadianMentalHealthAssociation,or any other registered Canadian charity (as indicated by the participant in the space provided). Following previous research (Johannesson & Persson, 2000; Nettle et al., 2013),wewereinterestedinwhetherornotaparticipantmadeadonation(ratherthan the total amount of money donated), and we therefore operationalized donations as a dichotomous variable (0 = no, 1 = yes).2 In the present sample, and similar to proportions of giving in some other laboratory-based dictator games (Nettle et al., 2013; Rigdon, Ishii, Watabe, & Kitayama, 2009), 65.3% of participants, male = 57.7%, female = 69.6%, v2(1, N = 524) = 7.52, p = .006, donated some of their potential winnings,suggestingthatconsistentwithpreviousliterature,womenweremoregiving thanmen(Eckel&Grossman,1998). Self-reportedmatingsuccessandmatingsuccessindices(sexualhistoryvariables) Self-reported mating success was again measured using self-perceived mating success scale(SPMS;Landoltet al.,1995).AsinStudy1,respondentsagainself-reportedon(1) theirnumberofconsensuallifetimesexpartners,(2)theirnumberofconsensualcasual sexpartners,andforthoseinaromanticrelationship(foratleastonemonth)andwho reportedhavinghadsexwiththeircurrentpartneratleastonce,and(3)thenumberof timestheyhadengagedinconsensualsexualintercourseoverthepast30 dayswiththat partner.Ofthetotalsample,250participants(47.7%)metthecriteriaforcurrentlybeing inaromanticrelationshipwithapersonwhomtheyhadpreviouslycopulatedwith(101 men, 149 women). In Study 2, participants additionally reported their total number of lifetimedatingpartners,aswellastheirtotalnumberofsexpartnerswithinthepastyear. Personalitydimensions The 44-item Big Five Inventory (BFI; John & Srivastava, 1999) was used to measure extraversion versus introversion (a = .86), agreeableness versus antagonism (a = .75), conscientiousness versus lack of direction (a = .60), neuroticism versus emotional stability(a = .83),andopennessversusclosednesstoexperience(a = .73).Participants respondtoeachitemusinga5-pointLikert-typescale(1 = disagreestrongly,5 = agree strongly). Narcissism The16-itemNarcissisticPersonalityInventory(NPI)wasusedtomeasuretraitnarcissism (Ames,Rose,&Anderson,2006).TheNPI-16hasshowngoodfacevalidity,discriminant, and predictive validity. Each item consists of two response items, and the respondent places an‘X’besidethestatement thatmostcloselydescribestheirfeelingsandbeliefs aboutthemselves.Anexampleitemisasfollows:‘Ireallyliketobethecenterofattention ORItmakesmeuncomfortabletobethecenterofattention’.Themeasureshowedgood internalconsistency(a = .72). 2Thevariable‘amountofmoneydonated’wasalsocollectedbutwasnotnormallydistributed,Shapiro–WilkW(524)=.81, p=.0001,andwasthusexcludedfromfurtheranalyses.

Description:
demonstrate one's skills as a good hunter and thus one's value as an ally or mate ( To the extent that altruism is desired by potential mating partners, it is .. extraversion). Self-report mating success. Lifetime sex partn ers. Life time.
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