The pursuit of unhealthy behaviors, such as smoking or binge drinking, not only carries various downside risks, but also provides pleasure. A parsimonious model, used in the literature to explain the decision to pursue an unhealthy activity, represents that decision as a tradeoff between risks and benefits. We build on this literature by surveying a rural population in South Africa to elicit the perceived riskiness and the perceived pleasure for various risky activities and to examine how these perceptions relate to the pursuit of four specific unhealthy behaviors: frequent smoking, problem drinking, seatbelt nonuse, and risky sex. We show that perceived pleasure is a significant predictor for three of the behaviors and that perceived riskiness is a significant predictor for two of them. We also show that the correlation between the riskiness rating and behavior is significantly different from the correlation between the pleasure rating and behavior for three of the four behaviors. Finally, we show that the effect of pleasure is significantly greater than the effect of riskiness in determining drinking and risky sex, while the effects of pleasure and riskiness are not different from each other in determining smoking and seatbelt nonuse. We discuss how our findings can be used to inform the design of health promotion strategies.

Recent developments in the application life history theory to human development indicate two fundamental dimension of the early environment – harshness and unpredictability – are key regulators life history strategies. Few studies have examined the manner with which these dimensions influence development, though age at menarche (AAM) and age at first sexual intercourse have been proposed as possible mechanisms among women. Data from the Avon Longitudinal Study of Parents and Children (N = 3,645) were used to examine direct and indirect effects of harshness (financial difficulties) and unpredictability (paternal transitions) on lifetime and past year sexual partners during adolescence and young adulthood. Genetic confounding was addressed using an AAM polygenic score (PGS) and potential gene-by-environment interactions were also evaluated using the PGS. Path model results showed only harshness was directly related to AAM. Harshness, unpredictability, and AAM were indirectly related to lifetime and past year sexual partner number via age at first sexual intercourse. The PGS did not account for any of the associations and no significant interactions were detected. Implications of these results for developmental models derived from life history theory are discussed as well as the role of PGSs in gene–environment interplay research.

Male mating success depends on various traits and factors, and correctly identifying these traits can be key in the context of pest management. For tephritid pests, controlled through the sterile insect technique (SIT) traits, such as male size, can be manipulated through mass-rearing procedures. Thus, it is particularly important to understand whether male size can favor mating success. Here, we evaluated mating success of males of different sizes in Anastrepha ludens and Anastrepha obliqua, two species controlled through SIT. For both species, a morphometric analysis was performed of mated and unmated mass-reared and wild males in field cages. In both A. ludens and A. obliqua, wild females did not discriminate their mates based on male size and mated more frequently with wild males regardless of size. For mass-reared males, we found no evidence of an advantage of the large males compared to small males in mating success. However, we did find differences between the morphometric traits of mass-reared and wild males. In A. ludens, traits associated to mating success were Face Width (FW), Head Width (HW), Thorax Length (TL) and Wing Length (WL), and for A. obliqua were FW, HW, WL and WW (Wing Width). Overall, FW and TL were more consistent predictors of mating success. In conclusion, female choice seems to suggest multivariate selection, confirming that overall body size (expressed as pupal diameter, which is highly correlated with weight) is not a decisive factor in male mating success in these two species. However, morphological traits such as FW, HW, TL, WL and WW may be relevant in mating preference of wild female.

COVID-19 pandemic and the related restrictions had a significant impact on the living and working conditions as well as the everyday behavior and mental health condition. Aim of the current analysis was to examine the impact of the input-deprived circumstances on the sexual life characteristics. An online survey carried out after a few weeks of the first nation-wide lockdown was enacted in Hungary. 1,755 persons participated in the first wave (50.4% males). Relationship and sexual life satisfaction, sexual intercourse and masturbation frequency were assessed with additional single-item questions about the subjective change (5-pont Likert scale; 1=“decreased significantly”; 5=“increased significantly) in these characetristics since the epidemiological restrictions had been introduced. Furthermore, several potential protective and risk factors were measured (depressive symptoms, perceived stress, loneliness, general well being, intolerance of uncertainty, sensation seeking, and COVID-19 related health anxiety). Linear regression models were calculated to assess which of the former variables predict the subjective changes of one’s sexual life. The analyses resulted in weak standardized coefficients. The subjective change in relationship satisfaction (mean 3.20, SD 0.94) and sexual satisfaction (mean 2.82, SD 0.73) were predicted positively by general well-being (β=.11–0.25, p<.01), and negatively by loneliness (β=-.14-0.19, p<0.01). Loneliness predicted negatively the subjective change in sexual intercourses (mean 2.75, SD 0.89) and masturbation frequency (mean 2.89, SD 0.84) (β=- .10–.12, p<.01), while sensation seeking had no effect (β=-.09, p<.01). The COVID-19 related health anxiety predicted negatively only the change in sexual life frequency (β=-.07, p<.05). The explained variances were rather small (1.7%-11.8%).

The aim of the present study was to investigate sexual behavior in a population of psychiatric patients affected by schizophrenia, schizoaffective disorder or bipolar disorder by means of an ad hoc questionnaire designed to explore the three phases of the sexual response: desire (or interest), arousal, and performance. The study assessed patients’ attitude toward sexuality, several aspects of their sexual behavior, including patients’ awareness of the risk of sexually transmitted diseases (STD), contraceptive strategy preferred by patients, and sexual effects of psychotropic medication. Patients reported a high frequency of sexual dysfunction, in particular, hyposexuality. Schizophrenia diagnosis and female gender were associated with lower levels of sexual performance. The impact of psychotropic drugs on patients’ sexuality was significant, with both positive and negative effects. Although 65.8% of patients reported to be concerned about the risk of contracting infections during sexual intercourse, most of them engaged in sexual behavior at high risk for acquisition and transmission of STD. Patients’ compliance with contraceptive measures was poor.

Concern has been expressed that human papillomavirus (HPV) vaccination programs might promote risky sexual behavior through mechanisms such as risk compensation, behavioral disinhibition, or perceived endorsement of sexual activity. This study assesses whether HPV vaccination status is associated with any differences in selected sexual behaviors among young sexually-active women in the US. Our dataset includes young, adult female respondents from questionnaire data collected in the National Center for Health Statistics' National Health and Nutrition Examination Survey from 2007 to 2014. The empirical approach implements a doubly robust estimation procedure, based on inverse probability of treatment weighting. For robustness, we implement several specifications for the propensity model and the outcomes model. We find no consistent association between HPV vaccination and condom usage or frequency of sex. Specifically, we find no evidence that HPV vaccination is associated with condom usage or with whether a person had sex more than 52 or more than 104 times per year. We find inconsistent evidence that HPV vaccination is associated with a person having sex more than 12 times per year. As in previous research, HPV vaccination does not appear to have a substantive effect on sexual behavior among young sexually-active women in the US.

HIV and sexually transmitted infections is a major threat for humanity in the world, especially in developing countries. The goals of this study were to: (a) analyze differences between genders in knowledge, attitudes, and risk behaviors about HIV/AIDS; and (b) evaluate the association between inconsistent condom use and knowledge, attitudes and risk behaviors about HIV/AIDS in Portuguese university students. Data were collected through a self-administered questionnaire from the Portuguese sample of the Sexual and Reproductive Health in University Students study (SRHUS), which is an extension of the Health Behavior in School-aged Children (HBSC) study for university students. This cross-sectional study provides national representative data of 3278 Portuguese university students. Results show that the majority is sexually active; the usual contraceptive methods more reported are the oral contraceptive and the male condom. However the prevalence of consistent condom use in last 12 months is 34.5% (men) and 31.7% (women). Men more often than women report engaging in sexual risk behaviors (occasional partners, sex associated to alcohol and drugs, STIs). In general, university students have good knowledge about how to protect themselves from HIV and have positive attitudes towards people with HIV/AIDS. This survey could be a useful guide in the development of campaigns or programs designed to convey accurate information about HIV transmission routes and prevention strategies and to dispel erroneous beliefs about HIV.

The aim of this study is to describe some characteristics of the sexual behavior of adolescents in Spain and to compare these characteristics according to gender, using a cross-sectional survey. Participants were 1.279 male and female adolescents who reported having had sexual intercourse. A questionnaire about sexual behavior was applied at their high schools and during school hours. Data were collected between 2006 and 2007. Mean age at the onset of sexual intercourse was 14.8 years in males and 15.0 years in females. Males and females were different according to the type of partner at the last sexual intercourse: 63.0% of males had a steady partner compared to 90.5% of females (p<0.01). The mean number of sexual partners during the last 12 months was higher in males than in females (M = 2.1 and M = 1.5 partners, for males and females, respectively, p<0.01). 50.0% of males had sexual intercourse under the effects of drugs versus 39.3% of females (p<0.01). STD and HIV prevention programs should be designed considering the differences according to adolescents’ sex.

It has been assumed that sexual activity during pregnancy would lead to an increased risk for miscarriage and other complications of pregnancy. Various studies showed no association of sexual behavior and pregnancy complications in single pregnancies. The aim of our study was to evaluate changes in sexual activity in women with twin pregnancies and whether a higher frequency of sexual intercourse was associated with an increased risk for pregnancy complications. We report on 50 women with twin pregnancies who answered a questionnaire on sexual behavior during pregnancy. At the time of delivery, patients were aged 31.0 ± 4.8 years. All women reported to have had sexual intercourse during pregnancy. In contrast to the first trimester in the vast majority of patients (41/50, 82.0%) the coital frequency decreased in the last month of pregnancy. Patients who had become pregnant after in-vitro fertilization were significantly less likely to have regular sexual intercourse than patients after spontaneous conception during early pregnancy (p = .002). No statistical significances were found when the rates of preterm delivery before the 37th gestational week were compared to the frequencies of sexual intercourse during early pregnancy and during late pregnancy (p >.05). In conclusion, our study demonstrates a decrease in frequency of sexual intercourse from early to late pregnancy in the specific collective of women with twin pregnancies, especially in women after in-vitro fertilization. There was no association between sexual activity and preterm delivery.

Two experiments were conducted in a subtropical latitude to determine the response of Alpine male goats to a treatment with artificially long days (experiment 1), and the response of anovulatory lactating Alpine does exposed to males treated only with artificially long days (experiment 2). In experiment 1, one group of males was kept under natural photoperiod (n = 4) while another was exposed to 2.5 months of artificially long days (16 h of light/day) from 1 December (n = 4). Plasma testosterone concentrations were determined weekly. Intensity of odor of males was determined every 2 weeks. Sexual behavior of bucks was observed during 3 days about 90 days after the end of the long day treatment. A treatment-by-time interaction was detected for testosterone secretion (P < 0.001). In control males, low plasma concentrations of testosterone were observed from March to June. In contrast, in long-day treated males, high levels of testosterone were observed from March to June (P < 0.05). A treatment-by-time interaction was detected for the intensity of male odor (P < 0.01). The male odor was stronger in long-day treated bucks than in untreated ones from March to June (P < 0.05). The number of ano-genital sniffing, nudging and flehmen was greater in long-day treated males than in untreated ones when exposed to anestrous does (P < 0.05). In experiment 2, one group of males was left under natural photoperiod variations (n = 5) and the other (n = 5) was submitted to the same photoperiodic treatment described in experiment 1. On 3 May, three untreated and three long-day treated males were put in contact with anestrous Alpine does left under natural photoperiod. Fertility was higher in does exposed to light-treated males (36/45, 80%) than those in contact with untreated ones (3/45, 7%; P < 0.05). Prolificacy was similar (P > 0.05) in does exposed to treated (1.8 ± 0.1) and untreated males (1.7 ± 0.3). These results indicate that the sexual activity of Alpine male goats raised in subtropical latitudes can be induced using only artificially long days and that such males are effective in stimulating reproductive activity in anovulatory females in late spring.

In most social species, position in the male social hierarchy and reproductive success are positively correlated; in humans, however, this relationship is less clear, with studies of traditional societies yielding mixed results. In the most economically advanced human populations, the adaptiveness of status vanishes altogether; social status and fertility are uncorrelated. These findings have been interpreted to suggest that evolutionary principles may not be appropriate for the explanation of human behavior, especially in modern environments. The present study tests the adaptiveness of social status with actual mating and reproductive data in a representative sample of males from an industrial society. Reproductive success, even when assessed by a more reliable measure of actual male fertility than the one commonly used, fails to correlate with social status. In striking contrast, however, status is found to be highly correlated with potential fertility, as estimated from copulation frequency. Status thus accounts for as much as 62% of the variance in this proximate component of fitness. This pattern is remarkably similar to what is found in many traditional societies and would result in a substantial positive relationship between cultural and reproductive success in industrial populations were it not for the novel conditions imposed by contraception and monogamy. Various underlying mechanisms are suggested for these findings, illustrating the value of current behavioral and reproductive data in the study of adaptation. It is concluded that evolutionary explanations of human behavior remain entirely relevant in modern societies.

The conceptual and investigative tools for the analysis of social behavior can be expanded by integrating biological theory, control systems theory, and Pavlovian conditioning. Biological theory has focused on the costs and benefits of social behavior from ecological and evolutionary perspectives. In contrast, control systems theory is concerned with how machines achieve a particular goal or purpose. The accurate operation of a system often requires feed-forward mechanisms that adjust system performance in anticipation of future inputs. Pavlovian conditioning is ideally suited to subserve this function in behavioral systems. Pavlovian mechanisms have been demonstrated in various aspects of sexual behavior, maternal lactation, and infant suckling. Pavlovian conditioning of agonistic behavior has been also reported, and Pavlovian processes may likewise be involved in social play and social grooming. Several further lines of evidence indicate that Pavlovian conditioning can increase the efficiency and effectiveness of social interactions, thereby improving their cost/benefit ratio. We extend Pavlovian concepts beyond the traditional domain of discrete secretory and other physiological reflexes to complex real-world behavioral interactions and apply abstract laboratory analyses of the mechanisms of associative learning to the daily challenges animals face as they interact with one another in their natural environments.

Using symbols from population biology, a continuum of reproductive strategies can be distinguished ranging from r, the production of large numbers of offspring provided with minimal care, to K, the production of few offspring nurtured intensively. While all humans are at the K end of the continuum, some are proposed to be more so than others. If multiple egg production is part of an r-reproductive strategy, certain facts may be ordered. Compared to mothers of singletons, for example, mothers of DZ twins nave a lower age of menarche, a shorter menstrual cycle, a higher number of marriages, a higher rate of coitus, more illegitimate children, a closer spacing of births, a greater fecundity, more wasted pregnancies, a larger family, an earlier menopause, and an earlier mortality. Further, all twins have a shorter gestation period, a lower birth weight, and a greater incidence of infant mortality, with DZ twins having a greater frequency of health disorders, a higher mortality rate, and a lower rate of enrollment in volunteer registries. Multiple birthing also occurs more frequently in families of lower than of higher social status, and in those of African than of European and especially than of Orientai descent.