Mate Choice

Multiple cues in mate selection: the sexual interference hypothesis

by George A. Lozano

Lozano, G. A. 2009. Multiple cues in mate selection: the sexual interference hypothesis. BioScience Hypotheses 2: 37-42

Animals use multiple cues when choosing mates, but it is not yet clear why a single signal would not suffice. In this... more Animals use multiple cues when choosing mates, but it is not yet clear why a single signal would not suffice. In this paper, drawing support from predation and “noise” effects on mate choice, marketing economics, and models on sexual signals, a new hypothesis explaining multiple sexual signals is proposed: the sexual interference hypothesis. The hypothesis is based on three well-supported premises: (1) selectivity decreases when mate assessment costs increase, (2) assessment costs increase when the propagation or reception of sexual signals is more difficult, and (3) males not only exploit such circumstances by courting females when choice is more difficult, but actively interfere with females’ preferences by making choice more difficult. The hypothesis argues that additional sexual signals evolve as a way for males to hinder female mate choice by interfering with the propagation and reception of other males’ sexual signals. Females respond by evolving the ability to glean meaningful information from signals despite males’ attempts at obfuscation. In turn, males respond by producing better interference signals and signals that are not so easily blocked. This co-evolutionary process increases the costs of assessment for females and the costs of signal production for males, and leads to a temporary equilibrium of honest advertising via multiple signals.

Testing a postulated case of intersexual selection in humans: the role of foot size in judgments of physical attractiveness and age

by Geoff Kushnick

Fessler, D., Stieger, S., Asaridou, S., Bahia, U., Cravalho, M., de Barros, P., Delgado, T., Fisher, M., Frederick, D., Geraldo Perez, P., Goetz, C., Haley, K., Jackson, J., Kushnick, G., Lew, K., Pain, B., Pisor, A., Sinaga, E., Sinaga, L., et al.
Evolution & Human Behavior 33:147-164 (2012)
doi: 10.1016/j.evolhumbehav.2011.08.002

The constituents of attractiveness differ across the sexes. Many relevant traits are dimorphic, suggesting that they... more The constituents of attractiveness differ across the sexes. Many relevant traits are dimorphic, suggesting that they are the product of intersexual selection. However, direction of causality is generally difficult to determine, as aesthetic criteria can as readily result from, as cause, dimorphism. Women have proportionately smaller feet than men. Prior work on the role of foot size in attractiveness suggests an asymmetry across the sexes, as small feet enhance female appearance, yet average, rather than large, feet are preferred on men. Previous investigations employed crude stimuli and limited samples. Here, we report on multiple cross-cultural studies designed to overcome these limitations. With the exception of one rural society, we find that small foot size is preferred when judging women, yet no equivalent preference applies to men. Similarly, consonant with the thesis that a preference for youth underlies intersexual selection acting on women, we document an inverse relationship between foot size and perceived age. Examination of preferences regarding, and inferences from, feet viewed in isolation suggests different roles for proportionality and absolute size in judgments of female and male bodies. Although the majority of these results bolster the conclusion that pedal dimorphism is the product of intersexual selection, the picture is complicated by the reversal of the usual preference for small female feet found in one rural society. While possibly explicable in terms of greater emphasis on female economic productivity relative to beauty, the latter finding underscores the importance of employing diverse samples when exploring postulated evolved aesthetic preferences.

MHC genotype and ornamentation

by Mats Grahn

Fashion and age in pheasants: age differences in mate choice

by Mats Grahn

Female choice selects for a viability-based male trait in pheasants

by Mats Grahn

MHC genotype and male ornamentation: genetic evidence for the Hamilton-Zuk model

by Mats Grahn

Good genes, oxidative stress and condition dependent sexual signals

by Mats Grahn

Testing a postulated case of intersexual selection in humans: The role of foot size in judgments of physical attractiveness and age

by Anne Pisor

Co-author. Article in press, Journal of Evolution and Human Behavior.

The constituents of attractiveness differ across the sexes. Many relevant traits are dimorphic, suggesting that they... more The constituents of attractiveness differ across the sexes. Many relevant traits are dimorphic, suggesting that they are the product of intersexual selection. However, direction of causality is generally difficult to determine, as aesthetic criteria can as readily result from, as cause, dimorphism. Women have proportionately smaller feet than men. Prior work on the role of foot size in attractiveness suggests an asymmetry across the sexes, as small feet enhance female appearance, yet average, rather than large, feet are preferred on men. Previous investigations employed crude stimuli and limited samples. Here, we report on multiple cross-cultural studies designed to overcome these limitations. With the exception of one rural society, we find that small foot size is preferred when judging women, yet no equivalent preference applies to men. Similarly, consonant with the thesis that a preference for youth underlies intersexual selection acting on women, we document an inverse relationship between foot size and perceived age. Examination of preferences regarding, and inferences from, feet viewed in isolation suggests
different roles for proportionality and absolute size in judgments of female and male bodies. Although the majority of these results bolster the conclusion that pedal dimorphism is the product of intersexual selection, the picture is complicated by the reversal of the usual preference for small female feet found in one rural society. While possibly explicable in terms of greater emphasis on female economic productivity relative to beauty, the latter finding underscores the importance of employing diverse samples when exploring postulated evolved aesthetic preferences.

Mate fidelity and intra-lineage polygyny in greater horseshoe bats

by Stephen Rossiter

Outbreeding increases offspring survival in wild greater horseshoe bats (Rhinolophus ferrumequinum)

by Stephen Rossiter

Multiple signals in human mate selection: A review and framework for integrating facial and vocal signals

by Andrew Dunn

T. J. Wells , A. K. Dunn , M. J. T. Sergeant, M. N. O. Davies (2009) Journal of Evolutionary Psychology

Evolutionary adaptation in variable environments is likely to give rise to several signals that can be used to... more Evolutionary adaptation in variable environments is likely to give rise to several signals that can be used to identify a suitable mate in multisensory organisms. The presence of multiple signals for sexual selection could be advantageous, limiting the chance of mating with a suboptimal partner and avoiding the costs of inferior progeny. Despite extensive research into isolated signals of attractiveness, the amalgamation of multiple signals in sexual selection is poorly understood, particularly in humans. Inferences regarding both the function and importance of such signals are therefore tentative unless the effects are considered together. Here, the literature regarding two evolved signals of attraction (cf. faces and voices) is reviewed in relation to a framework (Candolin 2003) for signal integration. It is argued that the functional nature of signals of attractiveness would be better studied through manipulation and experimentation with both single and multiple signals. Considering the prevalence of traits in relation to their combined effects may well provide a more fruitful and informative approach to human mate selection.

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For better or worse: reduced adult lifespan following early-life stress is transmitted to breeding partners

by Liliana D'Alba

Co-Authored with Pat Monaghan, Britt J. Heidinger, Neil P. Evans and Karen A. Spencer

Stressful conditions early in life can give rise to exaggerated stress responses, which, while beneficial in the short... more Stressful conditions early in life can give rise to exaggerated stress responses, which, while beneficial in the short term, chronically increase lifetime exposure to stress hormones and elevate disease risk later in life. Using zebra finches Taeniopygia guttata, we show here that individuals whose glucocorticoid stress hormones were experimentally increased for only a brief period in early post-natal life, inducing increased stress sensitivity, had reduced adult lifespans. Remarkably, the breeding partners of such exposed individuals also died at a younger age. This negative effect on partner longevity was the same for both sexes; it occurred irrespective of the partner's own early stress exposure and was in addition to any longevity reduction arising from this. Furthermore, this partner effect continued even after the breeding partnership was terminated. Only 5 per cent of control birds with control partners had died after 3 years, compared with over 40 per cent in early stress–early stress pairs. In contrast, reproductive capability appeared unaffected by the early stress treatment, even when breeding in stressful environmental circumstances. Our results clearly show that increased exposure to glucocorticoids early in life can markedly reduce adult life expectancy, and that pairing with such exposed partners carries an additional and substantial lifespan penalty.

Why do women not prefer much older men? a hypothesis based on alterations in male reproductive physiology related to increased age

by Wallisen Hattori

Evolutionary Psychology studies suggest that women prefer slightly older or similarly aged partners, although to date... more Evolutionary Psychology studies suggest that women prefer slightly older or similarly aged partners, although to date few hypotheses have been put forth to explain this pattern of choice. Several recent studies have shown changes in male reproductive parameters as a result of increased age. In the current review of medical literature, we found evidence that much older men are more likely to be infertile, women with much older partners are more likely to experience problems during pregnancy, and children of much older men are more likely to have genetic abnormalities. Based on these findings, we suggest that reproducing with much older men does not represent the best reproductive option for women, which would explain the female preference for only slightly older or similarly-aged mates.

Mate choice in female convict cichlids (Amatitlania nigrofasciata) and the relationship between male size and dominance

by Joseph Leese

We examined how male size and fighting ability influence a female’s mate assessment process and her eventual mate... more We examined how male size and fighting ability influence a female’s mate assessment process and her eventual mate choice in the monogamous convict cichlid, Archocentrus nigrofasciatus.  Females always chose the larger of two males when they were allowed to see a larger male next to a smaller one and when a larger male defeated a smaller one in a fight. They did not differentiate between large and small males when they did not see the two males together nor did they choose a dominant over a subordinate male when both were the same size. We suggest that females select on the basis of male size because it is a better predictor of both direct and indirect benefits (i.e. future competitive interactions and foraging ability) than only dominance behavior. In spite of selecting one male over the other early in the courtship period, females continued to visit both males until spawning. Our evidence supports that this assessment behavior is a bet-hedging tactic rather than the female’s indecision as to which male will be her mate. 

Glenn Shepard, Jr. 1998. Is Beauty In the Eye of the Beholder

by Douglas Yu

Yu, D. W. & Shepard, G. H. (1998) Nature, 396, 321-322.

Assortative mating in fallow deer reduces the strength of sexual selection. PLoS One 6, e18533

by Alan McElligott

Farrell ME, Briefer E, McElligott AG (2011) Assortative mating in fallow deer reduces the strength of sexual selection. PLoS One 6, e18533

MHC-mediated mate choice increases parasite resistance in salmon

by Sofia (Sonia) Consuegra del Olmo

Proc. R. Soc. B (2008) 275, 1397–1403

A role for ecology in male mate discrimination of immigrant females in Calopteryx damselflies?

by Maren Wellenreuther

Male hamsters discriminate estrous state from vaginal secretions and individuals from flank marks

by Javier delBarco-Trillo

14. delBarco-Trillo J, LaVenture AB, Johnston RE. 2009. Male hamsters discriminate estrous state from vaginal secretions and individuals from flank marks. Behavioural Processes. 82:18-24.

It is clear that male hamsters discriminate between the odors of individual, conspecific females, as shown by using... more It is clear that male hamsters discriminate between the odors of individual, conspecific females, as shown by using habituation–dishabituation methods. However, it is not clear from past research whether male hamsters are able to discriminate between the odors of estrous and non-estrous females. A series of habituation–dishabituation experiments was conducted to determine whether males discriminated between different estrous cycle states using two female secretions, those from flank-glands and vaginal secretions. We found that, when habituated to a female flank-gland secretion, males discriminated between this female and a second female on the test trial, whether both were in estrus, both were in diestrus, or one was in estrus and the other in diestrus. There was no difference, however, in the magnitude of their dishabituation response toward flank-gland odors of females in estrus and diestrus. These results suggest that males use flank-gland odors to gain information primarily about individuals. When tested with vaginal secretions in habituation–dishabituation tests, males only showed differences in investigation when the second female was in estrus, indicating that males use vaginal secretions to gain information primarily about reproductive state.

Anogenital distance predicts female choice and male potency in prairie voles

by Javier delBarco-Trillo

10. Ophir AG, delBarco-Trillo J. 2007. Anogenital distance predicts female choice and male potency in prairie voles. Physiol Behav. 92:533-540.

Anogenital distance (AGD) in rodents is a useful indicator of masculinization or feminization due to prenatal hormonal... more Anogenital distance (AGD) in rodents is a useful indicator of masculinization or feminization due to prenatal hormonal effects. If such cues convey useful information about both ‘maleness’ and more importantly mate quality, then females may select males based on this cue or other cues related to it. We tested this hypothesis by asking if female prairie voles (Microtus ochrogaster) preferred males with relatively longer AGDs and if AGD correlated with fitness enhancing characteristics such as sperm count, sperm size, and gonad size. Not only did preferred males have significantly longer AGD and larger testes than nonpreferred males, but AGD was directly related to the testes size, seminal vesicle size, and the number of sperm stored. We re-evaluated data collected in semi-natural field enclosures and discovered that males that were members of a pairbond had longer AGD than single males. This later result, taken under semi-natural conditions, was consistent with results we obtained in the laboratory. Taken together these data indicate that AGD serves as a useful cue of male potency and that females preferentially associate with males that demonstrate this masculinized phenotype. Moreover, these data imply that females may select mates based on their potential to effectively fertilize ova, a potentially important trait for a species that forms life-long pairbonds.