Theory and research on partnered parents suggests trade-offs between parenting and sexuality, with those trade-offs most pronounced among mothers of young children. However, little research has focused on how a growing demographic of single parents negotiates dating and sexual activity. The current study drew upon a 2012 nationally representative sample of 5,481 single Americans 21 years of age and older, of whom 4.3% were parents of a child age five or younger. Dependent variables were sexual thoughts, frequency of sexual activity, number of sexual partners in the past year, dates during the previous three months, and whether one was actively seeking a relationship partner. Covariates included parental age, sex/gender, sexual orientation, education, and income. Using the entire sample of singles, we found no main effects of number (0, 1, 2+) of children aged five years and younger or number of children aged two years and younger on dating and sexual behavior variables. Next, using analyses restricted to single parents (n = 2,121), we found that single parents with a child aged five years or younger, adjusting for covariates, reported greater frequency of sexual activity and first dates but no differences in other outcomes compared with single parents of older children.
Childhood family structure has been shown to play an important role in shaping a child's life course development, especially in industrialised societies. One hypothesis which could explain such findings is that parental investment is likely to be diluted in families without both natural parents. Most empirical studies have examined the influence of only one type of family disruption or composition (e.g. father absence) making it difficult to simultaneously compare the effects of different kinds of family structure on children's future outcomes. Here we use a large, rich data source (n=16,207) collected by Alfred Kinsey and colleagues in the United States from 1938 to 1963, to examine the effects of particular childhood family compositions and compare between them. The dataset further allows us to look at the effects of family structure on an array of traits relating to sexual maturity, reproduction, and risk-taking. Our results show that, for both sexes, living with a single mother or mother and stepfather during childhood was often associated with faster progression to life history events and greater propensity for risk-taking behaviours. However, living with a single father or father and stepmother was typically not significantly different to having both natural parents for these outcomes. Our results withstand adjustment for socioeconomic status, age, ethnicity, age at puberty (where applicable), and sibling configuration. While these results support the hypothesis that early family environment influences subsequent reproductive strategy, the different responses to the presence or absence of different parental figures in the household rearing environment suggests that particular family constructions exert independent influences on childhood outcomes. Our results suggest that father-absent households (i.e. single mothers or mothers and stepfathers) are most highly associated with subsequent fast life history progressions, compared with mother-absent households, and those with two natural parents.
The current study compares the effects of traditional and modern anti-homosexual prejudice on evaluations of parenting practices of same-sex and opposite-sex couples. Undergraduate university student participants (N = 436) completed measures of traditional and modern anti-homosexual prejudice and responded to a vignette describing a restaurant scene in which parents react to their childs undesirable behavior. The parents sexual orientation and the quality of their parenting (positive or negative quality) were varied randomly. It was predicted that participants who score higher in modern prejudice would rate the negative parenting behaviors of same-sex parents more negatively than similar behaviors in opposite-sex parents. It was also predicted that this modern prejudice effect would be most pronounced for male participants. Both hypotheses were supported.
In this study we explored the prevalence of regret following uncommitted sexual encounters (i.e., casual sex that occurs with someone once and only once or with someone known for less than 24 hours) among 138 female and 62 male Canadian university students, who were approximately 21 years of age. The majority of participants self-reported that they had experienced feelings of regret after an uncommitted sexual encounter. We found women reported feeling significantly more regret than men. However, mens regret was more closely tied to physical attributes than womens regrets. Regret was also influenced by the quality of the sex: high-quality sex rarely led to regret, while the reverse was true for poor-quality sex. In keeping with past studies, intoxication by alcohol and/or drugs was often listed as a source of regret by both men and women.
Human sexual behavior is highly variable both within and between populations. While sex-related characteristics and sexual behavior are central to evolutionary theory (sexual selection), little is known about the genetic bases of individual variation in sexual behavior. The variable number tandem repeats (VNTR) polymorphism in exon III of the human dopamine D4 receptor gene (DRD4) has been correlated with an array of behavioral phenotypes and may be predicatively responsible for variation in motivating some sexual behaviors, particularly promiscuity and infidelity.
The 7 repeat (7R) allele of the dopamine receptor D4 gene has been associated with attention deficit hyperactivity disorder and risk taking. On the cross-population scale, 7R allele frequencies have been shown to be higher in populations with more of a history of long-term migrations. It has also been shown that the 7R allele is associated with individuals having multiple ancestries. Here, we conduct a replication of this latter finding with two independent samples. Measures of subjects ancestry are used to examine past reproductive bonds. The individuals history of interracial/ancestral dating and their feelings about this are also assessed. Tentative support for an association between multiple ancestries and the 7R allele was found. These results are dependent upon the method of questioning subjects about their ancestries, with only finer-scale measures of ancestry being associated with 7R. Interracial dating and feelings about interracial pairing were not related to the presence of the 7R allele. This study provides continued support for a role for the 7R allele in migration and/or mate choice patterns. However, replications and extensions of this study are needed and the way ancestry/race is assessed must be carefully considered.
To test the relationship between androgen exposure, dopaminergic reward and sensation-seeking, we compared variation in salivary testosterone (T), 2D:4D digit ratio, facial masculinity, Zuckermans sensation-seeking scale (SSS) and the D4 dopamine receptor (DRD4) genes from 98 young men, between the ages of 18 and 23 years. In univariate analyses, both salivary T and facial masculinity were significantly correlated with the SSS boredom susceptibility subscale, while the presence of the 7-repeat allele (7R+) in the dopamine receptor D4 gene was associated with the SSS thrill and adventure-seeking and overall sensation-seeking. Neither left nor right 2D:4D digit ratio was associated with any sensation-seeking scale. In multivariate models, salivary T and facial masculinity were significant predictors of SSS boredom susceptibility, while 7R+ was a significant predictor of SSS thrill and adventure-seeking. For overall SSS, both 7R+ and salivary T were significant predictors. There was no significant interaction of 7R+ and androgen exposure for SSS or any of the SSS subscales. These results add to earlier reports of an association between T and sensation-seeking. In addition, our results also indicate that genetic variation in DRD4 is independently associated with SSS sensation-seeking.
The Decade of the Mind is a proposal for a research initiative focused on four areas of neuroscience, including mental health, high-level cognitive function, education, and computational applications. Organizing efforts to date have primarily included cognitive scientists, computer scientists, and engineers, as well as physicians. At the same time anthropologists have started to explore the implications of neuroscience for understanding culture. Here we suggest that evolutionary neuroscience can be used to bridge knowledge obtained by social scientists with that obtained in the neurosciences for a more complete appreciation of the mind. We consider such a perspective as neuroanthropology. We use embodiment, an anthropological concept that has been substantiated by recent findings in neuroscience, to illustrate an integrative biocultural approach within neuroanthropology and suggest future possible directions for research.
"Hookups," or uncommitted sexual encounters, are becoming progressively more engrained in popular culture, reflecting both evolved sexual predilections and changing social and sexual scripts. Hook-up activities may include a wide range of sexual behaviors, such as kissing, oral sex, and penetrative intercourse. However, these encounters often transpire without any promise of, or desire for, a more traditional romantic relationship. A review of the literature suggests that these encounters are becoming increasingly normative among adolescents and young adults in North America, representing a marked shift in openness and acceptance of uncommitted sex. We reviewed the current literature on sexual hookups and considered the multiple forces influencing hookup culture, using examples from popular culture to place hooking up in context. We argue that contemporary hookup culture is best understood as the convergence of evolutionary and social forces during the developmental period of emerging adulthood. We suggest that researchers must consider both evolutionary mechanisms and social processes, and be considerate of the contemporary popular cultural climate in which hookups occur, in order to provide a comprehensive and synergistic biopsychosocial view of "casual sex" among emerging adults today.
Arteries are under significant mechanical loads from blood pressure, flow, tissue tethering, and body movement. It is critical that arteries remain patent and stable under these loads. This review summarizes the common forms of buckling that occur in blood vessels including cross-sectional collapse, longitudinal twist buckling, and bent buckling. The phenomena, model analyses, experimental measurements, effects on blood flow, and clinical relevance are discussed. It is concluded that mechanical buckling is an important issue for vasculature, in addition to wall stiffness and strength, and requires further studies to address the challenges. Studies of vessel buckling not only enrich vascular biomechanics but also have important clinical applications.
Arteries are often subjected to torsion due to body movement and surgical procedures. While it is essential that arteries remain stable and patent under twisting loads, the stability of arteries under torsion is poorly understood. The goal of this work was to experimentally investigate the buckling behavior of arteries under torsion and to determine the critical buckling torque, the critical buckling twist angle, and the buckling shape. Porcine common carotid arteries were slowly twisted in vitro until buckling occurred while subjected to a constant axial stretch ratio (1.1, 1.3, 1.5 (in vivo level) and 1.7) and lumen pressure (20, 40, 70 and 100 mmHg). Upon buckling, the arteries snapped to form a kink. For a group of six arteries, the axial stretch ratio significantly affected the critical buckling torque ([Formula: see text]) and the critical buckling twist angle ([Formula: see text]). Lumen pressure also significantly affected the critical buckling torque ([Formula: see text]) but had no significant effect on the critical twist angle ([Formula: see text]). Convex material constants for a Fung strain energy function were determined and fit well with the axial force, lumen pressure, and torque data measured pre-buckling. The material constants are valid for axial stretch ratios, lumen pressures, and rotation angles of 1.3-1.5, 20-100 mmHg, and 0-270[Formula: see text], respectively. The current study elucidates the buckling behavior of arteries under torsion and provides new insight into mechanical instability of blood vessels.
In this mini-review, we consider an evolutionary biocultural perspective on human aging and sexuality. An evolutionary approach to senescence highlights the energetic trade-offs between fertility and mortality. By comparing humans to other primates, we situate human senescence as an evolutionary process, with shifts in postreproductive sexual behavior in this light. Age-related declines in sexual behavior are typical for humans but also highly contingent on the sociocultural context within which aging individuals express their sexuality. We briefly review some of the most comprehensive studies of aging and sexual behavior, both from the USA and cross-culturally. We frame these patterns with respect to the long-term relationships within which human sexual behavior typically occurs. Because sexuality is typically expressed within pair-bonds, sexual behavior sometimes declines in both members of a couple with age, but also exhibits sex-specific effects that have their roots in evolved sex differences.
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