Effects of food and mates on time budget in Aplysia fasciata: integration of feeding, reproduction, and locomotion

This study examines the time budgeted to different behaviors in Aplysia fasciata under three conditions: (1) animals have constant access to food and mates: (2) there is access to food, but not to mates; (3) neither food nor mates are present. The data suggest a number of rules underlying behavioral integration: (1) Feeding, reproductive behaviors, and activity seem to be natural categories for behavioral choice. Feeding and reproductive behaviors are controlled in tandem by a common arousal mechanism, while time left over after animals feed and reproduce is distributed in a fixed ratio between locomotion (crawling and swimming) and inactivity (immobility and movement in place). (2) Relative distribution between different forms of locomotion and inactivity is modified by changes in motivational state. More time is spent swimming than crawling when feeding and/or mating is prevented, while more time is spent moving in place than immobile when the arousal level is increased. (3) Feedback control of feeding and reproduction is asymmetric. Satiation of feeding inhibits the common arousal. In the absence of food, time spent on reproductive behaviors increases due to disinhibition of the common arousal. By contrast, positive feedback arising from sexual behavior excites the common arousal. When mating is prevented by removing potential mates, time spent feeding decreases. (4) Generally, animals choose between performing the three main categories of behavior. Although Aplysia simultaneously can feed and mate, or locomote and mate, they do so infrequently. By contrast, different types of reproductive behaviors (male mating, female mating, egg-laying) are commonly performed simultaneously.     

女性食物选择的演化视角：基于性选择过程的理论探讨

性选择在人类心理、行为等表型的演化过程中扮演了重要角色, 但其对女性食物选择的影响却相对较少被关注。性选择塑造了男女不同的择偶策略, 男性择偶时对女性外在吸引力的关注使得女性更加重视身材等外在吸引力信息。而女性身材与饮食的密切联系, 进一步提示性选择过程应该会对女性的食物选择产生影响。以之为基础, 梳理求偶动机激活可能引发的女性食物选择的变化, 以及女性生理期不同阶段在食物选择上的变异, 有助于了解性选择过程对女性食物选择的影响。未来研究中, 进一步从行为、激素、脑等不同层面剖析对应影响及涉及机制, 对该领域的长远发展有重要意义。     

Dissociation of sexual arousal and sexual proclivity in the garden snail, Helix aspersa

Sexual arousal (intensity of courtship) and sexual proclivity (tendency to court) in Helix aspersa can be reliably measured using externally observable correlates. Snails with sexual proclivity are significantly more likely to turn toward an anesthetized conspecific after contacting it than are sexually unreceptive snails. Sexual arousal can be inferred from the stage of a snail's genital eversion, which appears only during courtship. The higher the stage of the eversion, the shorter the time required to complete introductory courtship behavior and the higher the rate of successful copulation, the fewer the number of breaks and pauses during courtship, and the longer the time a snail will spend in contact with an anesthetized conspecific. Sexual proclivity has no effect on feeding or locomotory behavior; however, sexual arousal inhibits feeding and increases locomotor activity. Snails that were allowed daily contact with conspecifics required less time to complete introductory courtship behavior relative to snails that were isolated from conspecifics for 1 week. This suggests that daily contact increases sexual arousal. A greater percentage of isolated snails exhibited courtship behavior than did snails which had experienced daily conspecific contact. This suggests that isolation increases sexual proclivity. These differences indicate that sexual arousal is not merely due to an increase in sexual proclivity.     

Daily variation of multiple behaviors in Aplysia fasciata: integration of feeding, reproduction, and locomotion

Daily variations in feeding, reproductive behaviors, and activity level were examined under three conditions: (1) animals had access to food and mates; (2) there was access only to food; (3) neither food nor mates were present. Behaviors differed in amplitude of variations from their daily mean value. Egg-laying had the strongest tendency to be clustered. Amplitude of variations in courtship and swimming was larger than those of immobility, crawling, and feeding, while moving in place was the least clustered behavior. Changes in state affected the tendency to be clustered. When food and mates were present, amplitude of variations became progressively larger for immobility, moving in place, crawling, and swimming. Behaviors differed in the degree to which variations were patterned as a 1/day oscillation. Relatively little of the variability in crawling, moving in place, courtship, and egg-laying was due to a 1/day oscillation under any condition. By contrast, a large proportion of the variability of immobility, swimming, mating, and eating was modulated by a 1/day oscillation in at least one condition. The contribution of a 1/day oscillation to variability differed in the conditions examined. For immobility and swimming, when food and mates were present, the 1/day component of variability became smaller. By contrast, presence of mates led to an increase in the 1/day component of variability modulating feeding. Daily peaks of swimming and feeding were in phase with one another, and out of phase with mating and feeding. The ratio of locomotion to inactivity is constant, independent of change in external conditions. However, this ratio varied throughout the day. When food and mates were absent, variations of immobility and swimming were strongly related to variations in the inactivity ratio. When food and mates were added, this tendency decreased. The data suggest that daily variations in occurrence of behaviors can be accounted for by interactions between oscillators affecting Aplysia behavior and motivational variables. A 1/day oscillator has strong effects on mating, swimming, and immobility. The effect of the oscillator is modified by changes in motivational state.     

Female Japanese quail (Coturnix japonica) mated with males that harassed them are unlikely to lay fertilized eggs

Results of previous studies of courtship and mating in Japanese quail (Coturnix japonica) suggest that females avoid conspecific males because, while courting and mating, males engage in behaviors that are potentially injurious to females. However, prior experiments provided no direct evidence that females avoided harassing males. Here the authors show that a female quail choosing between a previous sex partner and an unfamiliar male avoids the former if he engaged in relatively many potentially injurious acts while courting and mating, (Experiments 1 and 2) and that males behaving aggressively toward mates are less likely than are gentler males to fertilize the females' eggs (Experiment 3). Male sexual harassment appears to be a tactic both aversive to female quail and relatively ineffective in fertilizing them.     

Alterations of male sexual behavior by learned aversions to hamster vaginal secretion

Male hamsters poisoned after their first adult exposure to the vaginal secretion of female hamsters became hesitant to approach and ingest the secretion. The same aversion-training procedure also altered the responses of males to estrous females, changing the latency, frequency, and duration of a variety of behaviors that are commonly taken as indexes of sexual attraction or arousal and of copulatory performance. The effects suggest that the aversions to vaginal secretion alter the perceived meaning of the secretion for male hamsters, and analysis of the correlations between various measures of sexual arousal and performance support the hypothesis that separate mechanisms underlie the effects of the secretion on appetitive and consummatory sexual behavior.     

危机情景下的亲社会行为：求偶动机对危机救助意愿的影响

危机救助指冒着生命危险去保护和拯救他人,这种行为多见于男性,但无法用进化论的个体选择观点解释。本研究基于进化心理学中代价信号理论,探索启动求偶动机对个体在危机情境下的冒险救助意愿的影响。结果表明,启动择偶动机会导致男性的危机救助意愿上升;而女性的危机救助意愿则在启动择偶动机后下降。这一结果支持如下观点：男性在危机情境下冒险救助的行为是一种代价信号行为,具有为吸引异性这一目标服务的功能。     

The sexual overperception bias is associated with sociosexuality

As reproductive rates have the potential to be higher in men than women, it is more costly (from an evolutionary perspective) for men to miss a mating opportunity than women. This asymmetry in costs has been proposed to result in men being more sensitive to cues to sexual opportunity than women, and thus men are more likely than women to misperceive sexual interest from opposite sex others. To investigate this sexual misperception bias, smiling male and female faces were presented to participants who were asked to judge whether the face appeared friendly or flirtatious. Participants also completed a sociosexual orientation questionnaire in order to assess their current attitudes towards sexual relationships. In general, we found that males perceive female faces as flirtatious significantly more often than females. However, our results also suggested that people with high scores on the sociosexuality inventory (who rated themselves as more likely to engage in short-term, casual relationships), regardless of sex, had a tendency to perceive the faces of potential mates as more flirtatious, and that this variable explained more variance than sex alone. Our findings demonstrate that sociosexuality may mediate biases in perceiving the sexual intent of others.     

Peacocks, Porsches, and Thorstein Veblen: conspicuous consumption as a sexual signaling system

Conspicuous consumption is a form of economic behavior in which self-presentational concerns override desires to obtain goods at bargain prices. Showy spending may be a social signal directed at potential mates. We investigated such signals by examining (a) which individuals send them, (b) which contexts trigger them, and (c) how observers interpret them. Three experiments demonstrated that conspicuous consumption is driven by men who are following a lower investment (vs. higher investment) mating strategy and is triggered specifically by short-term (vs. long-term) mating motives. A fourth experiment showed that observers interpret such signals accurately, with women perceiving men who conspicuously consume as being interested in short-term mating. Furthermore, conspicuous purchasing enhanced men's desirability as a short-term (but not as a long-term) mate. Overall, these findings suggest that flaunting status-linked goods to potential mates is not simply about displaying economic resources. Instead, conspicuous consumption appears to be part of a more precise signaling system focused on short-term mating. These findings contribute to an emerging literature on human life-history strategies.     

Pair-bonded humans conform to sexual stereotypes in web-based advertisements for extra-marital partners

Partners advertisements provide advertisers with access to a large pool of prospective mates, and have proven useful in documenting sex differences in human mating preferences. We coded data from an Internet site (AshleyMadison.com) catering to advertisers engaged in existing pair-bonded relationships. While we predicted that pair-bonding may liberate advertisers from conforming to sexual stereotypes of male promiscuity and female choosiness, our results are uniformly consistent with those stereotypes. Our findings thus provide further evidence that human mating behavior is highly constrained by fundamental biological differences between males and females.     

A sexual selection theory longitudinal analysis of sexual segregation and integration in early adolescence

The three objectives in this longitudinal study were motivated by sexual selection theory. The theory specifies the role of sexually segregated groups and the effects of dominance in male groups and relational/indirect aggression in female groups for heterosexual relationships. Using a multi-method, multi-informant, longitudinal design we studied youngsters (N=138) across their first two years of middle school. First, we examined the nature of change in segregation and dating popularity across two years during early adolescence. Second, a model derived from sexual selection theory is tested to explain the ways in which boys and girls are nominated for hypothetical dates (dating popularity). Third, we examined the role of "poke and push courtship" behavior in boys' and girls' dating popularity. Results indicate that although groups did not become more integrated with time, changes in peer group sexual integration co-varied dynamically with dating popularity. Secondly, dominance-related strategies were more important for boys than girls in dating popularity whereas indirect, or relational, aggression strategies were more important for girls than boys. Third, "poke and push courtship" behaviors did not influence peer group integration or dating.     

Medial preoptic area/anterior hypothalamus and sexual motivation

The medial preoptic area/anterior hypothalamus (MPOA/AH) is a brain site derived from proliferative zones from the diencephalon and telencephalon. It is probably this characteristic that makes this brain region participate in different physiological and behavioral functions. The present review addresses the role of the MPOA/AH in the control of male sexual behavior. It is clear that the MPOA/AH is a crucial site in the control of sexual behavior in males of all species studied to date. But although many different publications have followed the contribution of Heimer and Larsson there is no agreement as to what is specifically the role of the MPOA/AH in sexual behavior. At least three hypotheses have been presented. The first one suggests that this brain region is involved in the consummatory aspects (execution) of sexual behavior. The second indicates that the MPOA/AH is involved in the appetitive components (motivation) of masculine sexual behavior. The third hypothesis considers that MPOA/AH neurons are involved in the regulation of consummatory and appetitive aspects of sexual behavior. From the literature reviewed, it will become evident that the evidence supporting a role of the MPOA/AH in the execution of sexual behavior is based on a number of limited studies not easy to interpret. On the other hand, several lines of evidence using a variety of methodologies support the notion that the MPOA/AH is involved in the motivational aspects of male sexual behavior.     

Childhood sexual behavior as an indicator of sexual abuse: professionals' criteria and biases

Some sexual behaviors are related to child sexual abuse experiences, but none unequivocally. Therefore, professionals might use non-empirical-based criteria and be biased when detecting and reporting victims. To check this hypothesis, we presented 974 Spanish and Latin American professionals from different fields (Psychology, Education, Health, Social Services, Justice, and Police Force) with hypothetical situations of child sexual behavior (varying the sex, age and behavior) by using an experimental vignette method based on Factorial Survey. Participants were asked to indicate whether such behaviors are a sign of abuse and whether they would report them. We also measured demographic, academic, professional and attitude factors. According to the analysis, professionals' suspicion of abuse is more affected by personal factors, whereas their reporting intention depends more on situational factors. The main criterion adopted is the type of sexual behavior, with professionals being more likely to suspect and report in response to aggressive sexual behavior and precocious sexual knowledge. Professionals' attitudes to sexuality seem to generate biases, as those who are erotophobic are more likely to suspect abuse. None of the sexual behaviors was seen as evidence of abuse.     

The Evolution of Stalking

We propose that stalking tactics have been shaped by evolutionary processes to help solve mating problems. These include: (1) acquiring new mates, (2) guarding existing mates to prevent defection, (3) fending off mate poachers, (4) poaching someone else’s mate, (5) interfering with intrasexual competitors, (6) reacquiring ex-mates, (7) sexual exploitation and predation, and (8) guarding kin from sexual exploitation. We hypothesize several, gender-differentiated design features of psychological adaptations, including sensitivity to adaptive problems for which stalking was an ancestral solution and cognitive biases that function to motivate and perpetuate stalking behaviors. Although often abhorrent, cost-inflicting, and illegal, stalking sometimes enables successful adaptive solutions to problems of mating and within-gender competition faced by both men and women.     

The effect of light on the sexual behavior of Drosophila affinis

Drosophila affinis is a species whose mating is facilitated by light. Although sexually mature D. affinis males court D. affinis males and females vigorously in the light, they do not perform any of the courtship behaviors in the dark. This lack of courtship is not caused by the males and females being unattractive in the dark, since D. affinis males and females elicit high levels of courtship from Drosophila melanogaster males in light and in darkness. Fertility tests confirmed previous observations that mating occasionally occurs in the dark, suggesting that some D. affinis males are capable of courting in the dark.     

Men's media use, sexual cognitions, and sexual risk behavior: testing a mediational model

Efforts to link media use to adolescents' sexual initiation have produced somewhat inconsistent results, perhaps as a result of the limited framing of the question. This study sought to expand current approaches by sampling college students instead of high school students, by investigating a range of sexual behaviors and media formats, and by testing a model that featured sexual cognitions as mediators. We tested our model with a sample of 796 heterosexual, male college students who reported on their regular consumption of 4 media (prime-time TV programs, music videos, movies, and men's magazines); their attitudes toward abstinence, the male sexual role, and nonrelational sex; their perceptions of peer sexual behavior; and several aspects of their sexual behavior (e.g., number of sexual partners). Findings revealed strong support for our mediated model, with exposure to men's magazines and movies contributing most strongly to their sexual cognitions, and with men's cognitions, in turn, contributing heavily to their sexual behavior. Some direct connections from media use to sexual behavior also emerged. Together, the findings provide insight into both potential mechanisms for and new approaches to addressing this issue.     

"Central arousal" and sexual responsiveness in the snail, Helix aspersa

In molluscs, a "central arousal" system is thought to positively modulate both an animal's level of activity and its behavioral responsiveness. This hypothesis is examined in Helix aspersa by testing the relationships between activity, feeding, and sexual behavior. Activity, feeding, and mating exhibit parallel daily rhythms. Snails are most active, and eat and mate most frequently, during scotophase and the first 3 h of photophase. Handling and injections of serotonin (5 x 10(-7) m/kg body wt) increase general activity. Inducing activity during late photophase increases food consumption, but it does not induce sexual activity. Moreover, serotonin and handling have no effect on sexual arousal; treated snails show no increase in genital eversion stage and require the same length of courtship as controls. If snails are sexually deprived, increasing activity in late photophase does increase copulation frequency, but snails do not copulate more frequently than do unhandled snails tested during early photophase. These results suggest that while manipulations thought to increase central arousal do increase activity and responsiveness to food stimuli, they do not directly affect sexual proclivity or sexual arousal. Moreover, the relationship between feeding and sexual behavior differs between Helix and Aplysia. This difference between the two species may be related to the differences in their reproductive strategies.     

Implicit motives and sexual conservatism as predictors of sexual behaviors

This study was designed to provide an assessment of the relationship between the two most important implicit motives and the most frequently studied sexual behaviors. A community sample of 102 men and 92 women completed measures of implicit power and affiliation-intimacy motives, sexual conservatism, social desirability, and sexual behavior. For men, high power motivation was positively associated with the number of sexual partners and the frequency of sex. There was an interaction between sexual conservatism and power motivation in women. For women low in sexual conservatism, high power motivation was positively associated with the number of sexual partners and with earlier initiation to intercourse and oral sex. There were few associations between affiliation-intimacy motivation and sexual behaviors; however, women high in this motive reported later initiation to oral sex.     

Human sexual conflict from molecules to culture

Coevolutionary arms races between males and females have equipped both sexes with mutually manipulative and defensive adaptations. These adaptations function to benefit individual reproductive interests at the cost of the reproductive interests of opposite- sex mates, and arise from evolutionary dynamics such as parental investment (unequal reproductive costs between the sexes) and sexual selection (unequal access to opposite-sex mates). Individuals use these adaptations to hijack others' reproductive systems, psychological states, and behaviors-essentially using other individuals as extended phenotypes of themselves. Such extended phenotypic manipulation of sexual rivals and opposite-sex mates is enacted by humans with the aid of hormones, pheromones, neurotransmitters, emotions, language, mind-altering substances, social institutions, technologies, and ideologies. Furthermore, sexual conflict may be experienced at an individual level when maternal genes and paternal genes are in conflict within an organism. Sexual conflict may be physically and emotionally destructive, but may also be exciting and constructive for relationships. By extending the biological concept of sexual conflict into social and cultural domains, scholars may successfully bridge many of the interdisciplinary gaps that separate the sciences from the humanities.     

Susceptibility to sexual victimization and women’s mating strategies

Women show stable individual differences in mating strategies ranging from short-term to long-term. Short-term mating strategies may put women at greater risk of sexual victimization through increased exposure to risky situations or to men most inclined to pursue a strategy of sexual coercion. To test these predictions, we studied female college students who had experienced a completed rape, an attempted sexual victimization, or no sexual victimization. Women’s mating strategies were assessed through the Sociosexual Orientation Inventory. Victims further reported whether they engaged in consensual intimate behaviors with their victimizer before or after the victimization. Victims of completed rape scored highest on short-term mating strategy pursuit; non-victims scored lowest; women experiencing attempted victimization scored between these two groups. Victims of completed rape also more frequently reported consensual kissing and intercourse with their victimizer before and after the victimization than women who experienced attempted victimization. The findings of this study should not be interpreted as blaming the victim, but rather as identifying circumstances that put women at greater risk. Clearly, perpetrators are to blame for sexual victimization. Discussion focuses on future research directions and on practical implications for reducing rates of sexual victimization.