Men's Reproductive Investment Decisions Mating, Parenting, and Self-perceived Mate Value Coren L. Apicella and Frank W. Marlowe Harvard University Using questionnaire data completed by 170 men, we examine variation in paternal investment in relation to the trade-offbetween mating and parenting. We found that as men's self-perceived mate value increases, so does their mating effort, and in turn, as mating effort increases, paternal investment decreases. This study also si- multaneously examined the influence on parental investment of men's mating effort, men's perception of their mates' fidelity, and their perceived resemblance to their offspring. All predicted investment. The predictors of investment are also tested independently for men who are still in a relationship with the mother of their chil- dren and those that are separated from her. Finally we examine how self-perceived mate value affects how men respond to variation in paternity confidence. Men with a self-perceived low mate value were less likely to respond to lowered mate fidelity by reducing their parental investment compared with men with a self-perceived high mate value. KEY WORDS: Mate value; Mating effort; Paternity confidence; Parental investment; Reproductive strategies B y mammalian standards, human males contribute substantially to the care of their young (Clutton-Brock 1991; Alexander and Noonan 1979), although con- siderable variation exists in the amount of care they provide both within (Draper and Harpending 1982) and between (Hewlett 1992; Marlowe 2000) cultures. This variation has been explained in part by the trade-off between parenting and mat- ing--between being cads and dads (Draper and Harpending 1982, 1988). Received February 21, 2005; revisions requested May 15, 2005; final version received December 26, 2005. Address all correspondence to Coren Apicella, Department of Anthropology, Harvard University, Peabody Museum, Cambridge MA 02138, USA. E-mail: apicella@fas.harvard.edu Human Nature, Spring 2007, Vol. 18, No. 1, pp. 2 2 - 3 4 . 1045-6767/98/$6.00 =. 15