9.2: Puberty, Sexual Behavior, and Sexual Health in Adolescence
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Learning Objectives
By the end of this section, you will be able to:
- Explain the changes involved in puberty and the ranges of pubertal timing
- Describe current statistics on adolescent sexual behavior
- Describe factors related to early sexual intercourse and associated health risks including unplanned pregnancy and STIs
- Identify the various types of sex education and the ways they impact sexual health and behaviors
Braden and Ashley were both sixteen years old when they met and have been in a relationship for two years. They became each other’s first sexual partners and have been enjoying that intimacy for the past year. Ashley began taking the birth control pill a few months after they started having intercourse, and they agreed to use external condoms as a backup method of contraception and to prevent contracting any STIs. Recently, though, Ashley calls Braden less often and the frequency of sexual activity has also declined, as their relationship changes over time. During puberty and the adolescent period, many teens become curious about their bodies and may begin having sexual experiences and relationships; physical and emotional development and characteristics, sociocultural differences, self-esteem, and sexuality all influence the scope, timing, and pace of these experiences.
Puberty
The term puberty describes the process of a child’s transition to physical and reproductive maturity, and the period during which it occurs. Puberty lasts for about four years on average. It typically begins between the ages of eight and thirteen years in females, and between nine and fourteen years in males (NIH, 2024). Its onset is influenced by many factors, both biological and environmental.
The visible signs of puberty are evident in physical developments that are categorized into primary sex characteristics and secondary sex characteristics. The primary sex characteristics are physical developments that are directly related to the ability to reproduce: changes in the ovaries and uterus in females, and the testes and penis in males. For males, spermarche (sometimes called semenarche) is the first ejaculation; this marks the start of the ability to reproduce. This first ejaculation is often experienced as a nocturnal emission, or while they are asleep. For females, menarche , the onset of menstruation, marks this stage. The secondary sex characteristics are physical developments that accompany primary sex characteristics but are not directly related to the ability to reproduce. These include breast development in females (called thelarche), growth of underarm and pubic hair (adrenarche) in both sexes, and facial hair and a deepening voice in males.
The timing of the onset of puberty varies from individual to individual, but typically these developments follow the same sequence of changes. Biological, environmental, and sociocultural factors play a role in this timing. Figure 9.4 shows the typical timelines for various aspects of pubertal development in males and females. Notice, for example, that some of the earliest changes for females are growth of the ovaries and breasts, while for males, growth of the testis occurs before other aspects of puberty.
Biological Factors Affecting Pubertal Development and Timing
The onset of puberty is influenced by a variety of biological factors, including genetics, physical changes in the body’s muscle and fat mass, production of hormones, the functioning of the hypothalamus-pituitary (HPA) axis, and the development of puberty-related glands (Figure 9.5).
The HPA is essential for physical and sexual development during puberty (Figure 9.6). At the beginning of puberty, the hypothalamus signals the pituitary gland to release sex-specific hormones that act on the testes in males and ovaries and females. The brain releases a hormone called gonadotropin-releasing hormone (GnRH). GnRH triggers the pituitary gland—a small but significant gland that controls the production of several major hormones—to secrete follicle-stimulating hormone (FSH) and luteinizing hormone (LH) into the bloodstream. This in turn begins the series of changes that are associated with puberty, transforming the body to be capable of reproduction.
Link to Learning
Watch this 2-minute neuroscience video about the hypothalamus and pituitary gland to understand their roles and how they interact.
Factors such as early activation of the HPA, family history, genetic variations, and dealing with additional stressors are known predictive factors for early onset of puberty in females and males (Farello et al., 2019; Gaydosh et al., 2018). Additionally, in females, a certain amount of body fat is necessary for the onset of puberty for two reasons: first, a body composition that is low in fat might not have enough energy stored to support the physical changes that come with puberty. Second, body fat is linked to the production of estrogen , a key hormone in the development of the female reproductive system and the maintenance of its functions.  The hormone leptin is also thought to play a role in triggering puberty (Ahmed et al., 1999; Blum et al., 1997; Evans et al., 2022), and it is released into the bloodstream by adipose tissue (fat stores). When fat stores are at a level sufficient to indicate a healthy adolescent, leptin may signal the hypothalamus to begin releasing the cascade of hormones that sets puberty in motion (Murray & Clayton, 2013). Thus, the intricate interplay between genetics , stress, body fat, and hormones influences the timing of puberty in females.
In males, the timing of puberty is less understood. Similar to females, higher levels of central fat mass distribution were found to be associated with early onset of puberty (Kindblom et al., 2006); however, the role of leptin and the underlying mechanism of its role were not clear (Kaplowitz, 2008). A longitudinal study found that the higher weight prior to puberty could predict the onset of puberty and could be a better predictor of puberty onset than BMI (Bygdell et al., 2021). Additionally, other researchers have found a link to earlier onset of puberty and higher type 2 diabetes risk (Ohlsson et al., 2020), which might have implications for males as they get older.
The timing of puberty has a strong genetic component (Hoyt et al., 201). The age at which an individual’s biological parents went through puberty is a strong determinant in the timing of puberty for their adolescent offspring (Wohlfahrt-Veje et al., 2016). Although timing of parents’ puberty is the strongest predictor of puberty, sociocultural factors also play a role. For example, a study on Korean adolescents found that boys without their fathers present in the household experienced spermarche about three months earlier than those with their fathers present, though there were no differences in timing of menarche for girls (Susie Lee & Semenchanko, 2023). In contrast, a study on adolescents in the United States found that girls whose fathers were absent experienced puberty earlier (Gaydosh et al., 2018). Additionally, Arim et al (2011) found that low socioeconomic status (SES) predicted early puberty in Canadian males and females. Researchers still do not fully understand these sociocultural influences, though many speculate that factors like family stress may speed up the onset of puberty. It is important to consider the implications of both nature and nurture as well as the ways nature and nurture interact to shape development.
Environmental and Sociocultural Factors Affecting Pubertal Development and Timing
Psychologists most often measure the timing of puberty by self-report. Adolescent girls are asked to report the date of their first menstrual cycle, while boys are often asked about the development of various secondary sex characteristics (Hoyt et al., 2020). Recall that for males, puberty starts with the first ejaculation, but often males are not able to clearly recall that event, whereas females can often accurately identify their first menstrual cycle. These data are key to understanding potential links to health outcomes later in life. Pubertal timing can influence age at sexual initiation, learning and growth, and physiological health (Leone & Brown, 2020; Torvik et al., 2021).
Environmental factors related to the timing of puberty have been most extensively explored in females, potentially because of concerns related to the health risks commonly found in early-maturing girls, such as unplanned and early pregnancies and increased risks of gender-based violence (Sommer et al., 2014). Research on males may have also been less common because adolescent males are less likely to discuss spermarche (Frankel, 2002). In fact, even though adolescent males commonly learned about puberty from their parents, most report that nobody talked to them about spermarche, either before or after (Frankel, 2002; Mercer, 2021). This may be in part because spermarche is most common at night during sleep, which affords males some greater privacy in the experience, whereas menarche ’s timing is less predictable. Most adolescent females report having advance knowledge or conversations in preparation for menarche, most often with their mother (Sooki et al., 2016).
In females, individual and environmental factors in pubertal timing include nutrition, body weight, household composition, exercise, environmental chemicals, and overall levels of stress. While acute stress may delay puberty for teens of disadvantaged SES in lower- and middle-income countries due to stunted growth (because of the lack of ample nutritious foods), emotional and behavioral difficulties could bring puberty onset forward by reducing physical activity and encouraging an unhealthy diet (Kelly et al., 2016). On the contrary, a lower SES is typically linked to a higher risk of overweight/obesity and a faster pace of physical and sexual maturation in high-resource environments like the United States. Furthermore, disparities in the timing of puberty among historically oppressed groups reflect the stress and impacts of systemic racism (Bleil et al., 2017; Glass et al., 2022).
Psychologists studying pubertal timing also ask adolescents whether they feel they look older than (an indicator of early puberty), younger than (an indicator of late puberty), or the same age (on time) as their peers. This is called peer-relative timing . In researching the consequences of pubertal timing, psychologists often measure two possibilities—whether early onset of puberty alone is associated with various outcomes or whether the significant factor is being “off-time”—whether early or late relative to peers. For instance, developmental research indicates that girls who experience early puberty are more likely to engage in risk-taking behaviors, begin sexual activity earlier, use tobacco and alcohol more frequently, and experience higher rates and higher severity of depression, anxiety and other mental health risks, and an increased risk of relationship difficulties (Graber, 2013; Mendle et al., 2007; Rapee et al., 2019). Overall, earlier pubertal timing, both objectively and relative to peers, put both girls and boys at risk during adolescence, while later timing was somewhat protective (Table 9.2).
| Females | Males | ||
|---|---|---|---|
| Adolescent Health Outcomes | Adolescent Health Outcomes | ||
| Early-Onset | Late-Onset | Early-Onset | Late-Onset |
| More socioemotional symptoms including depression and anxiety | Less antisocial behaviors | More antisocial behaviors | More depressive symptoms |
| More risk-taking behavior | Lower risk-taking behaviors | More risk-taking behaviors | Less antisocial behaviors |
| Victim of bullying/teasing | Less physical activity | Less sleep hours | Less physical activity |
| Higher BMI | Lower BMI | Higher BMI | Lower BMI |
| Higher self-reported good health in young adulthood | More depressive symptoms | Lower screen time in young adulthood | More sleep hours |
Hoyt and colleagues (2020) used a nationally representative longitudinal data set that followed adolescents into young adulthood. Their findings are consistent with previous studies that supported the early-timing hypothesis. If a teen hits puberty very early (before 84 percent of their peers), it is associated with several negative consequences. In females, it is linked to increased health risks and higher BMI. Higher BMI can, in turn, result in early physical maturation, growth of breasts, and teasing about appearance. Thus, early-maturing females are at a higher risk of appearance-related anxiety, eating disorders, and body dysmorphia symptoms (Zimmer-Gembeck et al., 2018). Males who enter puberty earlier than peers report more risk-taking behavior, more drug use (Dudovitz et al., 2015), more sex partners, more sleep, and higher BMI (Hoyt et al., 2020). Late-onset puberty for boys, however, may increase some risks such as depressive symptoms and lower physical activity (Hoyt et al., 2020). When it comes to the timing of puberty, research overall indicates it is a little easier for youth who are on time or late-onset, than for those who are early-onset.
Adolescents experiencing early-onset puberty have additional challenges: their bodies might be changing before they are emotionally mature enough to handle the impacts presented by secondary sexual characteristics such as breasts. This can put them at risk of gaining attention from older teens and adults who may expose them to behaviors they are unprepared for, such as early sexual experiences (Mendle et al., 2007), exposure to pornography (Nieh et al., 2019), or experimentation with substance use (Castellanos-Ryan et al., 2013). Being at a higher risk does not mean the adolescent will definitely experience negative outcomes, and many early-onset adolescents overcome the challenges of early puberty in adulthood or never experience these risks due to a supportive environment. For example, there are many protective factors that can reduce risks related to off-time puberty, especially high-quality caregiving including higher warmth (e.g., authoritative parent), better communication, and the caregiver having more awareness of how the adolescent spends their time (Mrug et al., 2008).
On a historical note, a long-standing trend is apparent in the timing of pubertal onset. In Western regions like the United States and Europe, age at menarche declined dramatically from about seventeen years in the early nineteenth century to about thirteen years by the middle of the twentieth century. Starting in the 1960s, the age of onset of puberty seemed to have leveled off in Europe and the United States, although minor but significant declines of two and a half to four months have been reported during the past twenty-five years (Aksglaede et al., 2009; Eckert-Lind et al., 2020; Rubin et al., 2009; Sorensen et al., 2012). This tendency is an example of a secular trend . A secular trend is a long-term trend that lasts for several years or even decades as it manifests in the living conditions of a population and highlights any imbalance in health trends within the same population.
The most likely explanation for the decline in age of menarche is that nutrition has steadily improved, generation over generation, allowing for the body to more effectively prepare for the physical changes of puberty. Higher SES is also predictive of an earlier age of menarche, most likely because greater access to resources typically allows for greater nutritional access. In some countries, a similar link has been found between higher socioeconomic status and declining age at menarche. For instance, in the Philippines, earlier menarche was characteristic of girls who lived in urban, higher SES households, characterized by higher maternal education, better housing, and household asset ownership (Adair, 2001). Also, studies in Nigeria and Bangladesh found that girls from families of higher SES, as indicated by parental education and/or occupation, had an earlier age at menarche compared to girls from families of lower SES (Hossain et al., 2010; Onyiriuka & Egbagbe, 2013). One study done in Italy additionally suggests that the age at menarche has started to level off because socioeconomic conditions such as nutrition and hygiene have stopped improving (Piras et al., 2020).
The timing of puberty and related experiences also varies considerably by race and ethnicity. Black girls experience pubertal changes such as breast growth, pubic hair development, and menarche earlier than non-Black girls (Keenan et al., 2014; Osinubi et al., 2022). Early childhood stress and trauma due to discrimination and racism may disproportionately affect Black girls’ HPA activation resulting in earlier puberty (Warner, 2017). For Black, White, and Hispanic girls, household stress and instability are often associated with both earlier puberty and earlier menarche, though this association was not found for Asian and Pacific Islander youth (Aghaee et al., 2020).
Extensive research suggests that sociocultural experiences during puberty can have long-lasting effects on youth development. Specifically, social-contextual factors, including parental and peer relationships, school experience, and neighborhood conditions, are associated with increased risks of delinquency or lower social competence for boys with earlier puberty (Klopack et al., 2020). For girls who experience puberty earlier, peer pressure, harsh parenting, and environmental uncertainty increase risks of delinquency and other externalizing behaviors (Klopack et al., 2020; Najman et al., 2009).
Additionally, researchers have found that how puberty timing affects mental health can vary based on race and ethnicity, especially when considering other environmental factors. For example, early-maturing Hispanic females and males experienced more mental health issues when inhabiting areas with a significant proportion of White population (Seaton et al., 2022; White et al., 2013). Relatively late maturing African American females reported more difficulty internalizing after facing peer victimization (Hamlat et al., 2014), and those with a strong sense of racial identity experienced more difficulties in predominantly White schools (Seaton & Carter, 2018). Thus, minoritized teens undergoing off-time puberty display higher risk for psychological problems within low ethnic minority schools and communities.
Link to Learning
Watch this overview of what adolescence means and the role of puberty during this time. This helpful recap highlights the biological basis of puberty and discusses some of the social factors teens experience.
 Adolescent sexuality is shaped by a variety of contextual factors from the individual level (e.g., biological and neurological growth, personality, gender identity) to social-contextual environmental levels (e.g., influences from parents and peers, school and neighborhood influences) to the broader cultural contextual levels (e.g., media, cultural values) (Kar et al., 2015). This results in wide variability in adolescent sexual behaviors, interests, and overall sexuality.
Sexual activity encompasses a wide range of behaviors aimed at experiencing pleasure or intimacy, including both solitary activities (like masturbation) and partnered activities (like kissing, touching, oral sex, vaginal intercourse, and anal intercourse). Partnered activities may or may not involve physical contact.   However, sex may also be the word used to describe other forms of sexual activity such as external stimulation of genitalia or other erogenous zones (e.g., nipples).
Adolescence is often a time of self-exploration, including different types of sexual practices, such as masturbation. However, teens in this developmental phase may also engage in risky sexual behaviors such as unprotected penile-vaginal intercourse (PVI) (Thoma et al., 2013) and intercourse under the influence of alcohol or drugs (Rosario et al., 2014). Hence, the development of adolescent sexuality can lead to undesirable consequences for some teens, including emotional distress, the risk of contracting STIs, and unplanned pregnancy.
The Centers for Disease Control and Prevention (CDC) has researched adolescent behaviors for several decades using a survey called the Youth Risk Behavior Surveillance System (YRBSS). Data are collected every two years on a nationally representative sample of more than 10,000 U.S. high school students in grades nine through twelve. The questionnaires are answered anonymously, and results for individual years are reported as well as trends that emerge across multiple years. These data provide a comprehensive picture of mental and physical health-related behaviors in teens.
In 2021, 30 percent of high school students reported having had sexual intercourse (CDC, 2021). Females and males reported similar rates (31 and 30 percent, respectively), and this pattern held true across ethnoracial groups, except for Asian American teens, with only 11 percent responding they had ever had sex. Further, LGBTQ+ teens reported having had sex at a slightly higher but not significantly different rate than their heterosexual peers (33 versus 29 percent, respectively).
The ten-year trend results from the YRBSS show a marked and steady decline in sexual activity. In 2011, the proportion of high school students who had ever had sex was 49 percent, but in 2021 that dropped to 30 percent. This means more than two-thirds of high school students have not had sexual intercourse. When asked to report whether they are currently sexually active, 21 percent of teens reported in the affirmative. Note that the word “intercourse” was not defined to the high school students who completed the survey, so they may have varied understandings of what counts as sexual activity or intercourse.   However, there is likely underreporting on surveys as many adolescents may underestimate the behaviors that count as sex or may have never had intercourse defined to them (Figure 9.7).
Knowledge and attitudes regarding sexual behavior are heavily influenced by where they acquire their knowledge—most often from parents, peers, or the media. While around 61 percent of adolescents learn some level of sex education and contraception knowledge from their parents, the next most common source of information is peers (Bleakley et al., 2018). Moreover, researchers have found that teenagers who engage in frequent discussions with their peers about sex tend to have more favorable perceptions regarding potential social advantages (such as increased popularity through sexual activity) and enjoyment linked to sex, while being less inclined to anticipate social consequences (like stigma or loss of self-esteem) associated with it (Bleakley et al., 2018; Ragsdale et al., 2014). Adolescents were also twice as likely to talk about sex with their mother/woman caregiver than their father/man caregiver, though they strongly preferred communicating with peers over either caregiver (Ragsdale et al., 2014).
Very few respondents to the 2021 YRBSS indicated they had had four or more sexual partners so far—just 6 percent—also down from the 2011 figures (18 percent for males, 13 percent for females). Of those who reported being sexually active, 52 percent reported using a condom during their most recent intercourse, 33 percent reported using hormonal birth control (such as the pill), and 10 percent reported effectively using both condoms and hormonal birth control together. The most used contraceptive method among teens between 2011 and 2015 remained the condom (reported by 97 percent of teen females), followed by withdrawal (60 percent) and the pill (56 percent) (Harper et al., 2018). These low rates of effective contraception increase the risks for unplanned pregnancy and for spreading an STI. A sexually transmitted infection (STI) is caused by a virus, bacteria, fungus, or parasite that can be spread through sexual contact. Several STIs such as HPV and chlamydia, often show no symptoms, so individuals might have an infection without realizing it. When an STI leads to noticeable symptoms, it is called a sexually transmitted disease (STD) (CDC, 2023).
Link to Learning
Teens and young adults are at a higher risk of STIs among sexually active individuals. Knowing the statistics and being informed, along with protecting yourself and getting tested for STIs, is important. Learn more about teen sexual health by watching this video.
 According to the CDC, 33 percent of adolescents (aged fifteen to seventeen years) have engaged in oral sex at least once (CDC, 2020). Adolescents may be more likely to engage in oral sex over vaginal intercourse because many do not consider it to “count” as sex or see its potential for leading to STI transmission (Buhi & Goodson, 2007; Strome et al., 2022). From these findings, oral sex is an important component of adolescent sexual experience and should receive attention from parents, educators, and health-care professionals.
The YRBSS also asks teens to report whether they had ever experienced any kind of sexual violence (including unwanted touching and kissing) or been forced to have sex. With an overall level of 11 percent of teens reporting such an experience, 18 percent of female adolescents and 5 percent of male adolescents have experienced some form of sexual violence. A higher proportion of American Indian/Alaskan Native youth (16 percent), multiracial youth (15 percent), and LGBTQ+ youth (22 percent) reported experiencing sexual violence compared to their peers from other racial andethnic groups.
Sexual Health: Early Intercourse, Adolescent Childbearing, and Sex Education
Psychologists have focused on the individual and environmental factors that predict and explain earlier first sexual intercourse, often defined as younger age at first sexual intercourse. The earlier initial intercourse happens, the greater is the increase in chances for negative health consequences. Research suggests that engaging in sexual intercourse at an early age may increase the likelihood of experiencing negative sexual health outcomes, including reproductive health problems, injuries, pregnancy complications, and socioemotional challenges with future sexual relationships.  Some of the positive outcomes of early sexual behavior are more specifically related to sexual stimulation and orgasm, not necessarily intercourse (Peragine et al., 2022). Some research indicates that in evaluating the long-term impacts of first interpersonal sexual experiences, whether the experience was perceived as positive and enjoyable including who you are with may matter more (Peragine et al., 2023).
Psychologists have identified many factors related to early first intercourse. Studies have consistently shown that early sexual intercourse is associated with early pubertal timing (e.g., Mrug et al., 2014; Price & Hyde, 2009), likely because older or similarly maturing adolescents may give extra attention, wanted or unwanted, and even pressure early-maturing adolescents into earlier sexual activity. Early sexual activity is also negatively correlated with school achievement, which means struggling in school or not having strong academic background is a risk factor for early sexual intercourse (Lanari et al., 2020; Price & Hyde, 2009; Wheeler, 2010). Individuals with high levels of aggression and diagnoses of conduct disorders also tend to have sexual intercourse earlier (Fairchild et al., 2019).
Data from U.S. ninth-grade and eleventh-grade children who completed the Minnesota Student Survey show that the relationship between adverse childhood experiences and adolescent sexual risk behaviors and teen pregnancy is strong (Anda et al., 2006; Song & Qian, 2020). A study of teenagers in Brazil found that both personal factors like living in institutions or on the street (versus with families), repeating a school year, and using illegal drugs, as well as family factors like feeling less supported by parents and having more independence from the family, were linked to when teenagers started having sex (Furlanetto et al., 2020).
Parent-child closeness has been shown as a factor in early sexual activity. When parents are distant, adolescents may bond more strongly with their peers, who may serve as positive or negative social influences (Giletta et al., 2021). A qualitative study done in South Africa found that household poverty, family conflict, detached parenting, and lack of sex education all had a negative influence on adolescent well-being and promoted early sexual behaviors (Anyanwu et al., 2020).  For instance, religiosity serves as a factor for abstaining from sexual activity among youth in Nigeria (Somefun, 2019).
Thus, family, school, and religious environments can affect teen behaviors and sexual activities. Some protective factors against early sexual initiation include higher socioeconomic status, affiliation with a religious group, sex education, parental monitoring, and knowledge about reproductive health (Lara & Abdo, 2016; Stephenson et al., 2014).
Adolescent Pregnancy and Childbearing
The impact of adolescents bearing their own children is well documented. Adolescents themselves are not finished with development and maturation and are thereby not as well prepared to begin raising another person. For example, a younger age of childbearing can reduce access to educational and socioeconomic advantages later in life (Wolfe et al., 2023). Indeed, adolescent parenthood hinders normative psychological development and is related to poorer psychological functioning (Huang et al., 2013; Mollborn & Morningstar, 2009). Early age of becoming a parent is also associated with a higher risk of poor parenting and intergenerational transmission of unhealthy behavioral risks, such as greater externalizing problems in children of younger caregivers (Lorber & Egeland, 2009). About 75 percent of teenage pregnancies are unplanned (Finer & Zolna, 2016).
Pregnancy and childbirth significantly affect girls’ high school dropout rates. While about 90 percent of females who do not give birth as teenagers graduate from high school, the rate of high school completion for teen parents is 50 percent by the age of twenty-two years (Perper et al., 2010). Teenage mothers therefore attain a lower level of education, have lower earnings, and become more likely to use social welfare services (Gorry, 2019). Teenage mothers are also less likely to attend college and less likely to complete college when they do attend (Diaz & Fiel, 2016). Overall, being a teenage mother often brings emotional, psychological, and social difficulties, although not all teenage mothers have the same experiences (H.H.S., 2023). Having children may motivate some teen parents to complete their education to pursue “a better life” (Harden et al., 2006) and strive for self-sufficiency (Harding et al., 2020).
Research on the experience of teenage fathers is more scarce, for several reasons. Teen mothers are less likely to put fathers’ information on the birth certificate (Landry & Forrest, 1995), and teen males are less likely than older fathers to affirm paternity (Paschal, 2013). Nonetheless, paternal involvement is important, and traits linked with young fatherhood might lead to situations that increase the chances of their offspring engaging in risky sexual behavior and becoming teenage parents themselves (Bamishigbin et al., 2019). For instance, sons of teen fathers were almost twice as likely to become teenage fathers compared to sons of older fathers, even when other risk factors were taken into consideration (Sipsma et al., 2010).
A positive development is that the U.S. teen birth rate (births per 1,000 females aged fifteen to nineteen years) has been declining since 1991. Birth rates dropped from 17.4 per 1,000 females in 2018 to 15.4 in 2020, a record low (Martin et al., 2021). Rates vary significantly among ethnoracial groups, but the downward trend is occurring in all groups. In 2020, American Indian/Alaskan Native adolescent females had the highest birth rate, followed by Hispanic and Black adolescents and then White adolescents (CDC, 2017, 2022) (Figure 9.8).
What accounts for these declines in adolescent childbearing rates? It is likely a combination of factors: greater access to and use of hormonal birth control and condoms, increased access to comprehensive sex education, access to family planning clinics, and an overall decline in sexual activity among teens (e.g., Lindbert et al., 2020). Evidence-based teen pregnancy prevention programs, youth-friendly reproductive health services, and parental and community support can continue to reduce teen pregnancy rates (Goodreau et al., 2020).
Sex Education
Sex education is an important tool not only in encouraging safe and healthy sexual behavior and choices but also in preventing STIs and unplanned pregnancies.  This type of education also may not define what counts as sexual intercourse.
- Abstinence-plus education also promotes waiting until marriage to have sex but provides information about contraception and condoms.

Current recommendations are to offer comprehensive sex education to adolescents in schools (Goldfarb & Lieberman, 2021). Several scientific, governmental, and non-profit organizations in the United States have been at the forefront of establishing the core features of a comprehensive sex education curriculum. The National Sexuality Education Standards, first released in 2012, included the following broad topics: healthy relationships, consent, anatomy and physiology, puberty and sexual development, gender identity, sexual orientation, sexual health, and interpersonal violence (Future of Sex Education Initiative, 2020).
How effective is such educational programming? A review of more than 1,500 published studies on all aspects of comprehensive sex education concludes this approach is a resounding success across multiple outcome measures (Goldfarb & Lieberman, 2021). The review highlights the importance of introducing such education as early in adolescence as possible, with some suggesting age-appropriate introduction as early as second or third grade (Lashof-Sullivan, 2015), carefully tailoring information to local needs and developmental appropriateness. Comprehensive sex education, in particular when it includes dating and communication content, has shown the following successful outcomes: reduced adolescent childbearing and STI transmission, improved prevention of and knowledge of dating violence, improved communication in romantic and dating relationships, greater appreciation of sexual diversity, reduced bullying of LGBTQ+ youth, reduced risk of sexual abuse, increased empathy and respect for others, improved positive self-image, a better sense of self-control and safety, increased gender awareness (knowledge and understanding of the concept of gender, the division of roles, and gender equality), and improved overall knowledge and socioemotional skills related to staying safe (Goldfarb & Lieberman, 2021). In short, it is an effective part of the conversation on adolescent sexuality.
 Before puberty, children should be educated on their own anatomy at a very basic level (e.g., learning the accurate term for the overall external genitalia, such as vulva), know how to assert boundaries about their own boundaries (stay safe), and know how to communicate with a trusted adult if they are at risk or experience harm (Walsh et al., 2018). Additionally, as children approach puberty, in middle childhood and early adolescence, they should get more detail on healthy relationships and be taught in more detail about their own bodies and anatomy (e.g., being able to identify the parts of the external and internal genitalia). For example, multiple studies find that a minority of middle and high school youth can accurately identify the parts of the female and male reproductive system, and many do not have basic knowledge related to STIs and sex (Deshmukh & Chaniana, 2020; Nayoan et al., 2020). In a research study of older students, it was found that around two-thirds were still unable to identify female and male reproductive system parts including the labia and clitoris (Ampatzidis et al., 2019). Finally, by puberty, transparent and open comprehensive sex education that includes discussing of healthy and unhealthy relationships, defining sexual behavior fully, and teaching about safe sex should be provided to all students to improve their physical and socioemotional health and well-being (Goldfarb & Liberman, 2021). Thinking back to your learning in Chapter 2 Genetic, Prenatal, and Perinatal Health, can you identify all the parts of the female and male reproductive systems (Figure 2.12)?
 With a sex-positive approach, open discussions with parents and health-care providers can help educate teens about their sexual desires and behaviors (Kågesten et al., 2016). Having comprehensive sex education and knowledge of reproductive system parts can also increase long-term sexual health and well-being into adulthood (Dienberg et al., 2023).
Consent Culture and Sex Education
Consent culture refers to a societal framework that prioritizes and promotes mutual agreement, respect, and communication in all types of interpersonal interactions, particularly those of a sexual nature. In a consent culture , individuals are encouraged to seek and provide explicit and affirmative consent before engaging in any activity or behavior that may affect others. It emphasizes the understanding that consent must be freely given, reversible, informed, enthusiastic, and specific to each interaction. It aims to create an environment where all individuals feel empowered to assert their boundaries and where consent is valued as a fundamental aspect of healthy relationships and interactions. This shift toward advocating for affirmative consent , often known as “yes-means-yes” approaches, aims to foster open communication between partners and reduce instances of sexual assault (Im et al., 2021; Jozkowski, 2015). These approaches acknowledge affirmative consent as a clear and voluntary agreement, communicated either verbally or nonverbally, among all parties involved in sexual activity (Willis & Jozkowski, 2018).
A study of U.S. high school students found that adolescents’ overall have favorable views toward affirmative consent (Javidi et al., 2021). The study also explored the correlations between attitudes toward affirmative consent and factors such as gender, beliefs about gender roles, and sexual activity status. Females and teens with more egalitarian views on gender roles exhibited more positive attitudes toward affirmative consent compared to males and those with less egalitarian views on gender roles (Javidi et al., 2021). These findings are consistent with previous research that noted college-aged women prefer a more explicit and affirmative consent process than college men (Muehlenhard et al., 2016).
Life Hacks: Sex-Positive Parenting Tips
Creating a sex-positive climate in the home is an important aspect of contemporary parenting (Saady, 2022). The statements, behaviors, and attitudes that make up this kind of parenting don’t mean caregivers are encouraging their teenager to have sex. Rather, they recognize that sex and sexuality are a natural, healthy, and pleasurable part of life, and they set the stage for safe exploration, boundary setting, and open communication. Teaching about consent is a key part of this approach to sexuality.
 When these expectations are not met, sex-positive parents communicate their disappointment and reinforce the agreed-upon parameters for future behavior. Shame and guilt are actively avoided.
Here are some other sex-positive parenting tips and practices:
- Use medically correct terms for sexual body parts and acts from early childhood onward.
- Discuss options for birth control and STI prevention.
- Discuss masturbation in healthy terms, including appropriate places to do it.
- Focus on the functionality of body parts rather than on their appearance.
- Model healthy sexuality with parents’ own adult partners, including showing affectionate and romantic aspects of sex like hand-holding, kissing, and cuddling.
- Have periodic and ongoing age-appropriate discussions about sex, tailored to the teen’s current knowledge and experiences.
In these ways, parents acknowledge adolescents’ emerging sexuality and take an active part in setting their child up for positive decisions and experiences around sexuality.
References
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53.8.2: Pheromones
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Pheromones are chemicals released by an organism into its environment enabling it to communicate with other members of its own species.
Pheromones in Insects
Alarm Pheromone : When an ant is disturbed, it releases a pheromone that can be detected by other ants several centimeters away. They are attracted by low concentrations of the pheromone and begin to move toward the region of increasing concentration. As they get nearer to their disturbed nestmate, their response changes to one of alarm. The higher concentration causes them to run about as they work to remedy the disturbance. Unless additional amounts of the alarm pheromone are released, it soon dissipates. This ensures that once the emergency is over, the ants return quietly to their former occupations. Honeybees also have an alarm pheromone (which is a good thing not to elicit around a colony of "Africanized" bees).
Trail Pheromone : Certain ants, as they return to the nest with food, lay down a trail pheromone. This trail attracts and guides other ants to the food. It is continually renewed as long as the food holds out. When the supply begins to dwindle, trailmaking ceases. The trail pheromone evaporates quickly so other ants stop coming to the site and are not confused by old trails when food is found elsewhere. And at least in one species of ant, trails that no longer lead to food are also marked with a repellant pheromone.
A stick treated with the trail pheromone of an ant (left) can be used to make an artificial trail which is followed closely by other ants emerging from their nest (right). The trail will not be maintained by other ants unless food is placed at its end. (Photos courtesy of Sol Mednick and Scientific American).
Queen Pheromone: Honeybee queens spend their lives literally surrounded by a retinue of worker bees. The queen emits a pheromone that is a complex mixture of unsaturated hydrocarbons, fatty acids, and other organic molecules. Among its effects:
- inducing the workers to feed and groom her
- inhibiting the workers from building queen cells and rearing new queens
- inhibiting ovary development in the workers
Sex Attractants
Hundreds of pheromones are known with which one sex (usually the female) of an insect species attracts its mates. Many of these sex attractants or their close chemical relatives are available commercially. They have proved useful weapons against insect pests in two ways:
- Male Confusion : Distributing a sex attractant throughout an area masks the insect's own attractant and thus may prevent the sexes getting together. This "communication disruption" has been used successfully against a wide variety of important pests. For example, the sex attractant of the cotton boll weevil has reduced the need for conventional chemical insecticides by more than half in some cotton-growing areas.
 By baiting traps with the appropriate pheromone, a build-up of the pest population can be spotted early. Even if a conventional insecticide is the weapon chosen, its early use reduces
- the amount needed
- damage to the crop
- cost to the grower
- possible damage to the environment.
The photo (courtesy of USDA) shows the feathery antennae of a male gypsy moth. These detect the pheromone released by the females (who do not fly). In some insects, a single molecule of sex attractant is enough to elicit a response.
Sexual Deception
- By an animal: Many species of spiders prey exclusively on moths of certain species and only on the males. Studies of one species of spider, Mastophora cornigera , show that it releases a mixture of volatile compounds that mimic the sex pheromone of the moth species it preys upon. Male moths flying upwind in search of a female end up eaten instead!
- By a plant: A number of species of orchids - each pollinated by the males of a single species of insect (wasps or bees) — emit the same pheromone that is the sex attractant by which females of the insect species attract the males for mating.
Pheromones in Mammals
Releaser Pheromones: Many mammals (e.g., dogs and cats) deposit chemicals in and/or around their "territory". As these vaporize, they signal to other members of the species of the presence of the occupant of the territory. Domestic rabbit mothers release a mammary pheromone that triggers immediate nursing behavior by their babies (pups). A good thing, too, as mothers devote only 5–7 minutes a day to feeding their pups so they had better be quick about it.
Many animals, including mammals, signal with alarm pheromones. Although neither the source nor the chemical nature of alarm pheromones are known in any mammal, stressed animals release something that triggers quick behavior (e.g., flight or fight) in other members of their species. The pheromone is detected in a special cluster of cells located at the very tip of the nose and thus in a position to detected airborne molecules even before the vomeronasal organ (see below) or nasal epithelium can. The detectors on these cells are primary cilia.
Primer Pheromones: Rats and mice give off pheromones that elicit mating behavior. However, the response is not immediate as it is in the releaser pheromones of mother rabbits and insects. Instead, detection of the pheromone primes the endocrine system of the recipient to make the changes, e.g., ovulation, needed for successful mating. Primer pheromones are detected by the olfactory epithelium with which normal odors are detected and also in most mammals (but not humans) by the vomeronasal organ (VNO) . The VNO is a patch of receptor tissue in the nasal cavity distinct from the olfactory epithelium. The receptors are G-protein-coupled transmembrane proteins similar to those that mediate olfaction, but encoded by entirely different genes. The neurons leading from the VNO take a separate path into and through the brain.
Human pheromones: It has long been noticed that women living close together (e.g., college roommates) develop synchronous menstrual cycles. This is thought to be because they release two (as yet uncharacterized) primer pheromones: (1) one prior to ovulation that tends to speed up the onset of ovulation in others and (2) one after ovulation that tends to delay the onset of ovulation in other women. Both pheromones are released from the armpits. The pheromones are not detected consciously as odors, but presumably trigger the hormonal changes that mediate the menstrual cycle.


27.3: Soap
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Learning Objectives
After completing this section, you should be able to
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write an equation to represent the formation of a soap.
- identify the structure of the fat required to produce a given soap.
- identify the structure of a soap, given the structure of the fat from which it is produced.
- describe the mechanism by which soaps exert their cleansing action.
- give a chemical explanation of the problems encountered when carboxylate soaps are used in hard‑water areas, and explain how they may be overcome by the use of sulphonate detergents.
Key Terms
Make certain that you can define, and use in context, the key terms below.
- hydrophilic
- lipophilic (hydrophobic)
- amphiphilic
- micelles
Soap making has remained unchanged over the centuries. The ancient Roman tradition called for mixing rain water, potash and animal tallow (rendered form of beef or mutton fat). Making soap was a long and arduous process.  Then, potash solution was added. Since water and oil do not mix, this mixture had to be continuously stirred and heated sufficiently to keep the fat melted. Slowly, a chemical reaction called saponification would take place between the fat and the hydroxide which resulted in a liquid soap. When the fat and water no longer separated, the mixture was allowed to cool. At this point salt, such as sodium chloride, was added to separate the soap from the excess water. The soap came to the top, was skimmed off, and placed in wooden molds to cure. It was aged many months to allow the reaction to run to completion.
All soap is made from fats and oils, mixed with alkaline (basic) solutions. There are many kinds of fats and oils, both animal and vegetable. As previously discussed, fats are usually solid at room temperature, but many oils are liquid at room temperature. Liquid cooking oils originate from corn, peanuts, olives, soybeans, and many other plants. For making soap, all different types of fats and oils can be used – anything from lard to exotic tropical plant oils.
Carboxylic acids and salts having alkyl chains longer than eight carbons exhibit unusual behavior in water due to the presence of both hydrophilic (CO 2 ) and hydrophobic (alkyl) regions in the same molecule. Such molecules are termed amphiphilic (Gk. amphi = both) or amphipathic . Fatty acids made up of ten or more carbon atoms are nearly insoluble in water, and because of their lower density, float on the surface when mixed with water. Unlike paraffin or other alkanes, which tend to puddle on the waters surface, these fatty acids spread evenly over an extended water surface, eventually forming a monomolecular layer in which the polar carboxyl groups are hydrogen bonded at the water interface, and the hydrocarbon chains are aligned together away from the water. This behavior is illustrated in the diagram on the right. Substances that accumulate at water surfaces and change the surface properties are called surfactants .
Alkali metal salts of fatty acids are more soluble in water than the acids themselves, and the amphiphilic character of these substances also make them strong surfactants. The most common examples of such compounds are soaps and detergents, four of which are shown below. Note that each of these molecules has a nonpolar hydrocarbon chain, the "tail", and a polar (often ionic) "head group". The use of such compounds as cleaning agents is facilitated by their surfactant character, which lowers the surface tension of water, allowing it to penetrate and wet a variety of materials.
When minute amounts of soaps are put into water, instead of forming simple solutions, the molecules become concentrated at the surface of the water, with the saltlike ends sticking down into the water and the hydrocarbon chains forming a layer on the surface. This arrangement greatly reduces the surface tension of the water and contributes to the startling properties of soap films and bubbles. At higher concentrations, the solutions become turbid as the result of micelle formation. Micelles are spherical aggregates of soap molecules, wherein the hydrocarbon chains form a region of low polarity that is stabilized by having the polar salt ends of the molecules in contact with the water. By gathering the hydrophobic chains together in the center of the micelle, disruption of the hydrogen bonded structure of liquid water is minimized, and the polar head groups extend into the surrounding water where they participate in hydrogen bonding.
The importance of soap to human civilization is documented by history, but some problems associated with its use have been recognized. One of these is caused by the weak acidity (pKa ca. 4.9) of the fatty acids. Solutions of alkali metal soaps are slightly alkaline (pH 8 to 9) due to hydrolysis. If the pH of a soap solution is lowered by acidic contaminants, insoluble fatty acids precipitate and form a scum. A second problem soaps are less effective in hard water, which is water that contains a significant concentration of magnesium, calcium and iron ions. These ions form precipitates with soap molecules, and this precipitate is often seen as a gray line on a bathtub or sink and is often called “soap scum”. Since soap forms a precipitate with these ions, it means that many of the soap molecules are no longer present in the solution. Therefore, soap will form fewer suds in hard water. “Soft water” is water that contains very few or no ions that precipitate with soap. Soap will therefore be much more effective in soft water than in hard water.
These problems have been alleviated by the development of synthetic soaps called detergents. Detergents are similar to soaps in that they have a charged head group and a long nonpolar tail group, but they are not prepared from natural fats or oils. Detergents are useful because they do not form precipitates with magnesium, iron or calcium ions, which means that they work in both soft and hard water. By using a much stronger acid for the polar head group, water solutions of detergents are less sensitive to pH changes. Also the sulfonate functions used for virtually all anionic detergents confer greater solubility on micelles incorporating the alkaline earth cations found in hard water. Variations on the detergent theme have led to the development of other classes, such as the cationic and nonionic detergents shown above. Cationic detergents often exhibit germicidal properties, and their ability to change surface pH has made them useful as fabric softeners and hair conditioners. These versatile chemical "tools" have dramatically transformed the household and personal care cleaning product markets over the past fifty years
Sodium Lauryl Sulfate (a non-biodegradable detergent)
After detergents started being widely used, it was discovered that they were not broken down in sewage treatment plants. Many streams and lakes became contaminated with detergents and large amounts of foam appeared in natural waters. Biodegradable detergents were then developed. Shown below is an example of a biodegradable detergent, sodium laurylbenzenesulfonate.
Sodium Laurylbenzenesulfonate (a biodegradable detergent)
Exercise \(\PageIndex{1}\)
Explain how soaps or surfactants decrease the surface tension of a liquid. How does the meniscus of an aqueous solution in a capillary change if a surfactant is added? Illustrate your answer with a diagram.
- Answer
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Adding a soap or a surfactant to water disrupts the attractive intermolecular interactions between water molecules, thereby decreasing the surface tension. Because water is a polar molecule, one would expect that a soap or a surfactant would also disrupt the attractive interactions responsible for adhesion of water to the surface of a glass capillary. As shown in the sketch, this would decrease the height of the water column inside the capillary, as well as making the meniscus less concave.
Exercise \(\PageIndex{2}\)
Draw the structure of calcium stearate, a component of soap scum.
- Answer
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(C 17 H 35 COO) 2 Ca 2 +


10.2.6: Media Reports of Sociological Research
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Learning Objectives
- Cite the major differences between scholarly and media reports of sociological research.
- Identify the kinds of questions that may remain unanswered in media reports of sociological research.
As you have probably already gathered, we are likely to encounter sociological research in the news and other media. For example, check out the American Sociological Association’s media coverage links ( www.asanet.org/press/media_co...highlights.cfm ). There you’ll see that for just one study, on the consequences of parental divorce for child development (Kim, 2011),Kim, H. S. (2011). Consequences of parental divorce for child development. American Sociological Review, 76, 487–511. there were 170 news articles describing the study and its findings over the course of one month, June 2011. This particular study provides a good example of the difference between the information provided about a study in a scholarly journal article and the media’s coverage of the same study.
Let’s look at some of the differences between the aforementioned study’s coverage in the media and its treatment in a scholarly journal. First, watch the following coverage from The View ’s August 24, 2011, program: http://theview.abc.go.com/video/hot-...s-divorce-kids . Once you have watched the clip, ask yourself what you have learned about the study. Who conducted the research described? What are the study’s key findings? How many people participated in the study? Who were those participants? What sorts of data were analyzed? Which findings were statistically significant? Also note what questions you still have about the study. Where might you go to get the answers to your questions?
After watching The View clip several times, I was able to gather that the study has two key findings: (a) a child is more negatively affected by losing a parent to divorce than by the tension that leads to the breakup, and (b) children’s math scores drop after a divorce but reading and “other skills” do not suffer. As far as who participated, I heard that “3-year-olds and so on” were the participants, though I am not certain how many of them participated. I also don’t know who conducted the study, who (if anyone) provided funding for the study, when the data were collected, and so on. But if you review the article published in the American Sociological Review (ASR) that reports results of the study, all these questions are answered.
You might be saying to yourself, “So what?” Perhaps you took note that The View coverage does mention that the study was published in the ASR. If you did notice this, then kudos to you. Because the ASR is a peer-reviewed publication of the American Sociological Association, we should have some confidence that the study is reputable. But we still don’t hear all the information that might shape what we choose to take away from this study. For example, a review of the ASR article will tell us that the data come from a sample of people who were in kindergarten from 1998 to 1999. Perhaps that is of little consequence, but we might wish to pause to consider whether or how our cultural social context has shifted since 1998 and how that might impact how kindergartners today respond to parental divorce. I am not at all suggesting that only studies whose data are seconds or days old hold value. (If that were the case, I’d say we can safely disregard any of my own publications.) Instead, I want to call your attention to some of the questions you might ask yourself as a responsible consumer of research.
In addition to all the times that sociological research does make the news, there are also instances when it does not but probably should. In June 2011, for example, an article on children’s gender nonconformity appeared in the New York Times (Hoffman).Hoffman, J. (2011, June 10). “Boys will be boys?” Not in these families. New York Times. Retrieved from http://www.nytimes.com/2011/06/12/fashion/new-challenge-for-parents-childrens-gender-roles.html?pagewanted=all The article took the perspective that children’s expressions of gender were natural and biologically ingrained. While we cannot say for certain that this isn’t true, we do know from many years of reputable and highly regarded research by sociologists of gender that gender norms and behaviors are in many cases constructed socially , not biologically. That the article omits this perspective and the voices of sociologists who do research in this area is unfortunate—both for New York Times ’ readers and for sociology.
Keeping in mind your knowledge about sociology and sociological research the next time you come across descriptions of sociological research in various media outlets, ask yourself some questions about the research you encounter.
- Where do you see sociological research described?
- How is it described?
- What information is present, and what is missing from the media account of sociological research?
- How and where might you access the details that are missing?
Keep an eye out for the absence of sociological research as well and consider the following:
- Are there programs or news stories that might be well served to incorporate sociological research findings?
- How might the inclusion of sociological research shift the story?
By asking yourself these questions as you go about your daily routine, you will have integrated sociological research into your everyday life.
KEY TAKEAWAYS
- Media reports of sociological research, while important, may leave key questions about the research unanswered.
- When reading media reports of sociological research, it is useful to follow up your reading by checking the original scholarly source in which the research is reported.
Exercises
- Find a report of scholarly research in a nonscholarly source other than a newspaper. What would you say are the key takeaways reported by the nonscholarly source? Next, find and read a scholarly source’s report of the same research. What would you say are the key takeaways reported by the scholarly source? How do the takeaways from each source differ? How are they similar? How has your own understanding of the work changed by reading the scholarly report?
- Find a news story that you think could have be strengthened by the inclusion of sociological research. How might the inclusion of sociological research shift the story?