Sex roles and sexual selection

Sexual selection has been portrayed as acting predominantly on males who compete with each other over copulatory access to females; selection was considered to be driven by females choosing between males at the pre- or postcopulatory level. However, a broader view of sexual selection is now emerging. Examining male discrimination between females and female-female competition has been beneficial in identifying factors influencing the direction and strength of sexual selection. Furthermore, consideration of processes such as sexual coercion or genetic incompatibility, which indirectly influence an individual's set of copulation partners, gamete set or their offspring success, has helped to clarify the ways in which sexual selection may operate. Moreover, there is increasing evidence that not all copulations translate directly to paternity and that paternity does not necessarily translate into successful offspring. Postcopulatory and postfertilization mechanisms that influence not only paternity share but offspring recruitment now require further consideration. The benefits to each sex of copulating with particular partners or with more than one partner remains an area of debate. More carefully designed studies which eliminate alternative possibilities or quantify the relative importance of different selective pressures will also benefit from considering that not all copulations function solely to inseminate or receive sperm. It is also now clear that not all individuals of one sex follow the same strategy. Examining the variation between individuals in reproductive behaviour, fertilization success and offspring success will be important in establishing the selective pressures and mechanisms underlying the operation of sexual selection. (c) 1998 The Association for the Study of Animal Behaviour.     

Parasites, animal production and sustainable development

Ecologically sustainable development is aimed at reducing environmental degradation while enabling economic development with equity between the developed and developing worlds and between generations. Parasite control in livestock can both contribute to, and take advantage of, sustainable agriculture. This will tend towards less intensive, lower input, diversified crop and animal production with less risk of parasite-induced losses and greater opportunities for integrated control including the exploitation of grazing management. Chemotherapy will continue to play a part but the most serious problem is resistance in the target species. Except for a few isolated issues, currently used parasiticides are relatively minor contaminants of the food supply or the environment. Nevertheless, the compounds of the future will need to be narrow-spectrum, non-persistent and rapidly degraded, with convenience in the hands of the user reduced in importance. Environmentally friendly alternatives to chemotherapy, including genetic resistance of hosts, vaccines, and biological control, show considerable promise and must be pursued. Sustainable systems pose optimisation problems and more attention must be given to systems research, models and products to aid decisions. If governments are serious about sustainable development, greater support will be needed for longer-term patient, multi-disciplinary research.     

Buss and sexual selection: The issue of culture.

Comments on D. M. Buss' (see record 1995-21138-001) comment on A. H. Eagly's (see record 1995-21141-001) discussion comparing the sexes in scientific research. The author disputes Buss' use of particular assumptions as facts and his concepts of culture, social behavior, and sexual selection. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Runaway ornament diversity caused by Fisherian sexual selection

Fisher's runaway process of sexual selection is potentially an important force generating character divergence between closely related populations. We investigated the evolution of multiple female preferences by Fisher's runaway process. There are two outcomes of runaway. The first is the evolution of mate preference to a stable equilibrium. This evolution occurs if the benefits of mate choice are sufficiently large relative to the cost of choice. Alternatively, mate preferences evolve cyclically. The rate and pattern of cyclic evolution depends primarily on the individual cost of choice and epistasis in the joint cost of choice. If there are small differences in natural selection (e.g., predation risk) between populations, cyclic evolution quickly leads to divergence in mate preferences and sexual ornaments and so to sexual isolation.     

Parental investment, sexual selection, and evolved mating strategies: Implications for psychoanalysis.

The author suggests that all major psychoanalytic theories posit a universal, ungendered human mind that is subsequently gendered by developmental experience. Thus, psychoanalysis has ignored built-in, innate differences between males and females. The concepts of distal versus proximal causes, and parental investment and sexual selection theory, along with some of the evidence for innate sex differences, are presented. An evolutionary understanding of gender is then applied to both psychoanalytic theory and practice. Contrary to postmodern reactions–suggesting that notions of innate factors or universals are essentially tools to enable those in a more powerful position (e.g. therapists) to impose controls and constraints on others–it is shown how a modern evolutionary understanding can actually enhance openness to a fuller range of human experience and possibility. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Childhood sexual abuse, adolescent sexual behaviors and sexual revictimization

OBJECTIVE: The aims of this study were to examine the extent to which exposure to childhood sexual abuse (CSA) was associated with increased rates of sexual risk taking behaviors and sexual revictimization during adolescence. METHOD: A birth cohort of 520 New Zealand born young women was studied at regular intervals from birth to the age of 18. At age 18 retrospective reports of CSA were obtained from sample members. Over the course of the 18 year study information was gathered on: (a) childhood, family, and related circumstances; and (b) the young women's history of sexual experiences from 14 to 18 years. RESULTS: Young women reporting CSA, and particularly severe CSA involving intercourse, had significantly higher rates of early onset consensual sexual activity, teenage pregnancy, multiple sexual partners, unprotected intercourse, sexually transmitted disease, and sexual assault after the age of 16. Logistic regression analyses suggested that the associations between CSA and sexual outcomes in adolescence arose by two routes. First, exposure to CSA was associated with a series of childhood and family factors including social disadvantage, family instability, impaired parent child relationships, and parental adjustment difficulties that were also associated with increased sexual vulnerability in adolescence. Second, there appeared to be a causal chain relationship between CSA and sexual experiences in which CSA was associated with early onset sexual activity which, in turn, led to heightened risks of other adverse outcomes in adolescence. CONCLUSIONS: The findings of this study suggest that those exposed to CSA have greater sexual vulnerability during adolescence. This appears to arise because: (a) the childhood and family factors that are associated with CSA are also associated with increased sexual risks during adolescence; and (b) exposure to CSA may encourage early onset sexual activity which places those exposed to CSA at greater sexual risk over the period of adolescence.     

Psychological sex differences: Origins through sexual selection.

Men and women clearly differ in some psychological domains. A. H. Eagly (see record 1995-21141-001) shows that these differences are not artifactual or unstable. Ideally, the next scientific step is to develop a cogent explanatory framework for understanding why the sexes differ in some psychological domains and not in others and for generating accurate predictions about sex differences as yet undiscovered. This article offers a brief outline of an explanatory framework for psychological sex differences—one that is anchored in the new theoretical paradigm of evolutionary psychology. Men and women differ, in this view, in domains in which they have faced different adaptive problems over human evolutionary history. In all other domains, the sexes are predicted to be psychologically similar. Evolutionary psychology jettisons the false dichotomy between biology and environment and provides a powerful metatheory of why sex differences exist, where they exist, and in what contexts they are expressed (D. M. Buss, 1995). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Women's history of sexual abuse, their sexuality, and sexual self-schemas.

In this study, the authors assessed 48 female survivors of child sexual abuse (CSA) and 71 female control participants using measures of adult sexual function, psychological function (i.e., depression and anxiety), and sexual self-schemas. The primary purpose of this study was to examine whether differences existed between women with and without a history of CSA in the way that they viewed themselves as a sexual person and, if so, whether such differences mediated the link between early unwanted sexual experiences and later adult sexuality. CSA survivors were found to view themselves as less romantic and passionate than women who were not abused. In particular, CSA survivors showed an inverse relationship between romantic/passionate sexual self-schemas and negative sexual affect during sexual arousal. The relationship between CSA and negative sexual affect was independent from symptoms of depression and anxiety, suggesting that the impact of CSA on sexual self-schemas may be independent from the impact that the abuse may have in other areas of the survivor's life. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dominant host range selection of vaccinia recombinants by rescue of an essential gene

The intergeniculate leaflet (IGL) is a distinct division of the lateral geniculate complex that participates in the regulation of the circadian rhythm through its projections to the circadian pacemaker located in the suprachiasmatic nuclei of the hypothalamus. A high number of neuropeptide Y (NPY) cell bodies has been described in the IGL by immunohistochemistry and in situ hybridization. The present study investigated whether NPY in the IGL is influenced by the length of the daily photoperiod. By using in situ hybridization we show a significant increase of the number of NPY mRNA containing neurons in the mid-part of the IGL of Syrian hamsters maintained in a short photoperiod compared to those kept in a long photoperiod. On the other hand, NPY mRNA expression per cell in the IGL is similar in both photoperiods tested.     

Females prefer leading males: relative call timing and sexual selection in katydid choruses

Females of several acoustic insects and anurans have recently been shown to orient preferentially to the leading of two identical male calls presented in close succession. We studied this phenomenon via two-choice phonotaxis trials in the neotropical katydid Neoconocephalus spiza and found that females avoided male calls occurring during an interval beginning immediately after the onset of a leading call. This avoidance occurred whether or not the following call was overlapped by the leader, indicating that the mechanism of preference for leading calls may represent a psychoacoustic precedence effect rather than simple call masking. We also found that females preferred leading calls as long as the amplitude of the following call was not more than 2 dB higher than the leader. Under certain circumstances, preferences for leading calls remained when females were presented with a sequence of four calls. Thus, preferences for leading calls probably influence a male's attractiveness and mating success in complex natural choruses: females are expected to orient towards males producing leading calls regardless of call length (and the probability of overlapping a following call), when the leading call is up to 1.5 times as distant as a follower, and when succeeded by multiple followers. We suggest that female preferences for leading male calls represent sensory biases that originated in contexts unrelated to sexual selection. None the less they currently play an important role in sexual selection and influence individual male signalling behaviour, and thus chorus structure. Copyright 1998 The Association for the Study of Animal Behaviour.     

Update in allergy and immunology

Internal medicine has witnessed astounding developments in our understanding of the immune system's role in the pathophysiology of many diseases. The present challenge is to harness this knowledge to develop more effective therapies for immune-related illness. Guidelines for the care of common illnesses such as asthma may encourage appropriate clinical application of advances in our armamentarium against immune disease.     

Childhood sexual abuse, stigmatization, internalizing symptoms, and the development of sexual difficulties and dating aggression.

Potential pathways from childhood sexual abuse (CSA) to subsequent romantic intimacy problems were examined in a prospective longitudinal study of 160 ethnically diverse youth with confirmed CSA histories. Participants were interviewed at the time of abuse discovery, when they were 8-15 years of age, and again 1-6 years later. Stigmatization (abuse-specific shame and self-blame) and internalizing symptoms (posttraumatic stress and depressive symptoms), more than abuse severity, explained which youth with CSA histories experienced more sexual difficulties and dating aggression. Stigmatization was found to operate as a predictive mechanism for subsequent sexual difficulties. Internalizing symptoms were not predictive of romantic intimacy problems, although they did show correlational relations with sexual difficulties and dating aggression. Early interventions such as trauma-focused cognitive-behavioral therapy that target stigmatization may be important for preventing the development of sexual difficulties in CSA youth. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of sex guilt, repression, sexual "arousability," and sexual experience on female sexual arousal during erotica and fantasy.

Hypothesized that, among women who were asked to fantasize about sex, erotic preexposure would facilitate arousal during the fantasy, and arousal would be greater among those who had less sex guilt, those who were more arousable, those who were more experienced, and sensitizers. 62 female Ss (aged 18–53 yrs) were randomly assigned to view either an erotic or a nonerotic videotape. All Ss then imagined and wrote out a sexual fantasy. Sexual arousal was measured subjectively by self-report ratings and physiologically by continuous vaginal photoplethysmograph recording. Ss high in sex guilt reported less arousal but showed significantly greater physiological arousal during the erotic videotape than did Ss low in sex guilt. For the high sex-guilt Ss, the erotic videotape facilitated physiological arousal during fantasy. Ss low in sexual arousability and low in sexual experience followed a similar pattern. No significant differences were found for repression-sensitization. Results point toward a pattern of behavioral inhibition that facilitates increased response to forbidden erotica. (36 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Need for approval, guilt, and sexual stimulation and their relationship to sexual responsivity.

Describes an experiment in which 111 male undergraduates were given the Marlowe-Crowne Social Desirability scale and the Mosher Forced-Choice Guilt Scale prior to reading a series of either sexual or neutral passages. Ss rated the extent to which they were sexually aroused, anxious, bored, angry, disgusted, and entertained, and then responded to a sexual double-entendre word association test. Responses indicate that Ss were significantly more sexually aroused after reading the sexual as opposed to the neutral passages. Need approval and guilt scores were not significantly related to stated degree of arousal or any of the other dimensions. Low need-approval Ss showed greater sexual responsivity to the entendres than highs, especially subsequent to reading the sexual passages. For the guilt variable, Ss with low sex guilt demonstrated greater sexual responsivity on the entendres regardless of whether they read neutral or sexual passages. Results suggest that these personality variables affect responding rather than affect arousal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)