class12.final

class12.final - From last time A growing body of studies...

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Unformatted text preview: From last time A growing body of studies demonstrate menstrual phase shifts in womens mate preferences: stronger preferences for more masculine traits near ovulation vs. at other times of cycle Dominant explanation for these effects in the existing literature is EPC/mixed mating theory Revisit the costs/benefits of the EPC argument: Selection for Extra-Pair Copulations Because women obtain genetic benefits only when fertile, but could pay the cost throughout the cycle, selection may have shaped female interest in men who possess indicator traits of good genes such that it changes across the cycle: increases when women are fertile (the few days to a week prior to ovulation; Jochle 1973) and decreases when not. (Gangestad et al., 2002) Day of Cycle Fertile window Cost of EPC Benefit of EPC EPC = extra-pair copulation No Alternative Explanations This feature of womens preferences [cycle shifts in preferences for the scent of symmetrical men] can be explained as a special design feature evolved to enable ancestral women to obtain genetic benefits from extra-pair mates while avoiding costs of seeking such benefits during periods of infertility. It is difficult to understand the nature of these preferences otherwise. Gangestad (2000: pp. 57- 58) At present, there is no clear alternative explanation for the patterns of findings reported above. Given that no current alternative model has the explanatory power and coherence that the good genes hypothesis has, this hypothesis is favored by the method of inference to the best explanation. (Gangestad et al., 2007) Between-Cycle Alternative Explanation Within-Cycle (EPC) Position : Shifts in mate preferences are designed to change behavior within a given cycle Since focuses on how preferences change within a cycle (fertile window vs. not), called within-cycle position Point is to pursue mixed mating strategy Brain mechanisms read hormonal signals to answer single question: Am I currently within the fertile window? Between-Cycle Position : Evolved mechanisms are designed to produce shifts in mating psychology between different cycles Holds that female mate preferences designed to shift over long periods of time (entire cycles) Brain mechanisms read hormonal signals to answer question: Am I currently in a fertile cycle? Mating Mechanisms in Less Fertile Cycles Mating Mechanisms in More Fertile Cycles continuous adjustment (Libido/preference for fitness indicators) Low Estrogen/Progesterone High Estrogen/Progesterone Lactation Food shortage High energy expenditure Illness/Stress No Lactation Sufficient food Moderate energy flux Healthy/low stress Continuous Adjustments in Fertility Ovarian hormones are continuously calibrated to signals that woman has sufficient energy to sustain pregnancy Lactational amenorrhea Strong suppression of estrogen and progesterone As nursing bouts decrease, gradual and continuous upregulation...
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This note was uploaded on 12/07/2009 for the course PSYCH 146 taught by Professor Rooney during the Fall '09 term at UCSB.

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class12.final - From last time A growing body of studies...

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