88-398: Just Seventeen , often referred to as J-17 , was a fortnightly magazine aimed at teenage girls, published by Emap from October 1983 to April 2004. A special preview edition was given away free with sister magazine Smash Hits on 13 October 1983, with the first issue published the following week, on 20 October (thereby alternating weeks with Smash Hits ). Just Seventeen had become
176-513: A positive feedback loop known as the Fisherian runaway produced by the secondary characteristic in one sex and the desire for that characteristic in the other sex. Male birds and fish of many species have brighter coloration or other external ornaments. Differences in size between sexes are also considered secondary sexual characteristics. The reproductive organs in male or female mammals that are usually identifiable at birth are described as
264-414: A continued decrease in subcutaneous fat and an obviously harder and more angular body form. Pubic hair distribution appears more adult but has not yet spread to the medial area of the thighs. The penis and scrotum are near adult size. Stage IV for boys, which occurs anywhere from 15 to 24 months after stage III, is difficult to pinpoint. At this time, the spurt of growth in height ends. There is facial hair on
352-401: A deeper voice and larger Adam's apple in boys, and development of breasts and more curved and prominent hips in girls) and a strong shift in hormonal balance towards an adult state. This is triggered by the pituitary gland , which secretes a surge of hormonal agents into the blood stream, initiating a chain reaction. The male and female gonads are thereby activated, which puts them into
440-480: A fairly regular sequence. The first places to grow are the extremities—the head, hands and feet—followed by the arms and legs, then the torso and shoulders. This non-uniform growth is one reason why an adolescent body may seem out of proportion. During puberty, bones become harder and more brittle. At the conclusion of puberty, the ends of the long bones close during the process called epiphysis . There can be ethnic differences in these skeletal changes. For example, in
528-453: A friend's or parent's assumptions. Adolescents also develop a more sophisticated understanding of probability. The appearance of more systematic, abstract thinking is another notable aspect of cognitive development during adolescence. For example, adolescents find it easier than children to comprehend the sorts of higher-order abstract logic inherent in puns, proverbs, metaphors, and analogies. Their increased facility permits them to appreciate
616-442: A girl is not fully fertile until several years after menarche, as regular ovulation follows menarche by about two years. Unlike males, therefore, females usually appear physically mature before they are capable of becoming pregnant. Changes in secondary sex characteristics include every change that is not directly related to sexual reproduction. In males, these changes involve appearance of pubic, facial, and body hair, deepening of
704-563: A great deal of research has been done on the cognitive and emotional processes underlying adolescent risk-taking. In addressing this question, it is important to distinguish whether adolescents are more likely to engage in risky behaviors (prevalence), whether they make risk-related decisions similarly or differently than adults (cognitive processing perspective), or whether they use the same processes but value different things and thus arrive at different conclusions. The behavioral decision-making theory proposes that adolescents and adults both weigh
792-566: A growth rate nearly identical to that of a toddler—about 10.3 cm (4 inches) per year for males and 9 cm (3.5 inches) per year for females. In addition to changes in height, adolescents also experience a significant increase in weight (Marshall, 1978). The weight gained during adolescence constitutes nearly half of one's adult body weight. Teenage and early adult males may continue to gain natural muscle growth even after puberty. The accelerated growth in different body parts happens at different times, but for all adolescents, it has
880-528: A high-fat diet and who are not physically active begin menstruating earlier, on average, than girls whose diet contains less fat and whose activities involve fat reducing exercise (e.g. ballet and gymnastics). Girls who experience malnutrition or are in societies in which children are expected to perform physical labor also begin menstruating at later ages. The timing of puberty can have important psychological and social consequences. Early maturing boys are usually taller and stronger than their friends. They have
968-646: A lower resting heart rate, a greater capacity for carrying oxygen to the blood, a greater power for neutralizing the chemical products of muscular exercise, higher blood hemoglobin and more red blood cells". Despite some genetic sex differences, environmental factors play a large role in biological changes during adolescence. For example, girls tend to reduce their physical activity in preadolescence and may receive inadequate nutrition from diets that often lack important nutrients, such as iron. These environmental influences, in turn, affect female physical development. Primary sex characteristics are those directly related to
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#17328848339001056-457: A major role in character and personality formation. Biological changes in brain structure and connectivity within the brain interact with increased experience, knowledge, and changing social demands to produce rapid cognitive growth (see Changes in the brain above). The age at which particular changes take place varies between individuals, but the changes discussed below begin at puberty or shortly after that and some skills continue to develop as
1144-551: A manifestation of higher levels of estrogen ; estrogen also widens the pelvis and increases the amount of body fat in hips, thighs, buttocks, and breasts. Estrogen also induces growth of the uterus , proliferation of the endometrium , and menstruation . Female secondary sex characteristics include: The increased secretion of testosterone from the testes during puberty causes the male secondary sexual characteristics to be manifested. Testosterone directly increases size and mass of muscles , vocal cords , and bones , deepening of
1232-410: A more sophisticated theory of mind . Adolescents reach a stage of social perspective-taking in which they can understand how the thoughts or actions of one person can influence those of another person, even if they personally are not involved. Compared to children, adolescents are more likely to question others' assertions, and less likely to accept facts as absolute truths. Through experience outside
1320-1061: A newfound priority in sexual attraction and dating, and risk-taking is required to impress potential mates. Research also indicates that baseline sensation seeking may affect risk-taking behavior throughout the lifespan. Given the potential consequences, engaging in sexual behavior is somewhat risky, particularly for adolescents. Having unprotected sex, using poor birth control methods (e.g. withdrawal), having multiple sexual partners, and poor communication are some aspects of sexual behavior that increase individual and/or social risk. Aspects of adolescents' lives that are correlated with risky sexual behavior include higher rates of parental abuse, and lower rates of parental support and monitoring. Related to their increased tendency for risk-taking, adolescents show impaired behavioral inhibition, including deficits in extinction learning . This has important implications for engaging in risky behavior such as unsafe sex or illicit drug use, as adolescents are less likely to inhibit actions that may have negative outcomes in
1408-598: A notable broadening of the hips as well as an adult fat distribution. Additionally, breast development is complete and hair in both the pubic region and armpits (axillary hair) will be darker and more widespread. In comparison to girls, it can be tricky to define when exactly sexual development in boys begins. For boys, puberty typically takes around 5 years to finish, as opposed to just 3 + 1 ⁄ 2 years for girls (menarche). By this point in time, they have already experienced their growth spurt and there are evident changes in their body shape – wider hips and fat distribution
1496-434: A positive feedback loop or runaway where the feature becomes hugely amplified. The 1975 handicap principle extends this idea, stating that a peacock 's tail, for instance, displays fitness by being a useless impediment that is very hard to fake. Another of Fisher's ideas is the sexy son hypothesis , whereby females will desire to have sons that possess the characteristic that they find sexually attractive in order to maximize
1584-445: A process referred to as metacognition . It often involves monitoring one's own cognitive activity during the thinking process. Adolescents' improvements in knowledge of their own thinking patterns lead to better self-control and more effective studying. It is also relevant in social cognition, resulting in increased introspection , self-consciousness , and intellectualization (in the sense of thought about one's own thoughts, rather than
1672-472: A species for mates, can explain observed differences between sexes in many species. Ronald Fisher , the English biologist , developed a number of ideas concerning secondary characteristics in his 1930 book The Genetical Theory of Natural Selection , including the concept of Fisherian runaway which postulates that the desire for a characteristic in females combined with that characteristic in males can create
1760-406: A specific order during puberty: The first facial hair to appear tends to grow at the corners of the upper lip, typically between 14 and 17 years of age. It then spreads to form a moustache over the entire upper lip. This is followed by the appearance of hair on the upper part of the cheeks, and the area under the lower lip. The hair eventually spreads to the sides and lower border of the chin, and
1848-442: A state of rapid growth and development; the triggered gonads now commence mass production of hormones. The testes primarily release testosterone , and the ovaries predominantly dispense estrogen . The production of these hormones increases gradually until sexual maturation is met. Some boys may develop gynecomastia due to an imbalance of sex hormones , tissue responsiveness or obesity . Facial hair in males normally appears in
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#17328848339001936-936: A typical aspect in maturing females. Because of their bodies' developing in advance, pubescent girls can become more insecure and dependent. Consequently, girls that reach sexual maturation early are more likely than their peers to develop eating disorders (such as anorexia nervosa ). Nearly half of all American high school girls' diets are to lose weight. In addition, girls may have to deal with sexual advances from older boys before they are emotionally and mentally mature. In addition to having earlier sexual experiences and more unwanted pregnancies than late maturing girls, early maturing girls are more exposed to alcohol and drug abuse . Those who have had such experiences tend to not perform as well in school as their "inexperienced" peers. Girls have usually reached full physical development around ages 15–17, while boys usually complete puberty around ages 16–17. Any increase in height beyond
2024-580: A weekly publication by early 1986. It quickly became the UK's market-leading teen-girl magazine until the launch of Sugar in 1994, after which sales began to fall. In 1997, the magazine was changed to a monthly format in response to declining circulation, and the magazine was finally closed in 2004, after losing a third of its readership. This teens magazine–related article is a stub . You can help Misplaced Pages by expanding it . See tips for writing articles about magazines . Further suggestions might be found on
2112-452: A willingness to take risks, teenagers would not have the motivation or confidence necessary to leave their family of origin. In addition, from a population perspective, there is an advantage to having a group of individuals willing to take more risks and try new methods, counterbalancing the more conservative elements more typical of the received knowledge held by older adults. Risk-taking may also have reproductive advantages: adolescents have
2200-412: Is spermarche , the first ejaculation , which occurs, on average, at age 13. For females, it is menarche , the onset of menstruation, which occurs, on average, between ages 12 and 13. The age of menarche is influenced by heredity, but a girl's diet and lifestyle contribute as well. Regardless of genes, a girl must have a certain proportion of body fat to attain menarche. Consequently, girls who have
2288-597: Is 10–11 for girls and 11–12 for boys. Every person's individual timetable for puberty is influenced primarily by heredity , although environmental factors, such as diet and exercise, also exert some influences. These factors can also contribute to precocious and delayed puberty . Some of the most significant parts of pubertal development involve distinctive physiological changes in individuals' height, weight, body composition, and circulatory and respiratory systems. These changes are largely influenced by hormonal activity. Hormones play an organizational role, priming
2376-590: Is a difficult task due to multiple factors such as family life, environment, and social status. Empirical studies suggest that this process might be more accurately described as identity development , rather than formation, but confirms a normative process of change in both content and structure of one's thoughts about the self. The two main aspects of identity development are self-clarity and self-esteem. Since choices made during adolescent years can influence later life, high levels of self-awareness and self-control during mid-adolescence will lead to better decisions during
2464-447: Is a physical characteristic of an organism that is related to or derived from its sex, but not directly part of its reproductive system . In humans , these characteristics typically start to appear during puberty —and include enlarged breasts and widened hips of females, facial hair and Adam's apples on males, and pubic hair on both. In non-human animals, they can start to appear at sexual maturity —and include, for example,
2552-451: Is a stage in the adolescent life cycle. For most, the search for identity begins in the adolescent years. During these years, adolescents are more open to 'trying on' different behaviours and appearances to discover who they are. In an attempt to find their identity and discover who they are, adolescents are likely to cycle through a number of identities to find one that suits them best. Developing and maintaining identity (in adolescent years)
2640-455: Is an excitatory neurotransmitter. During the synaptic pruning that occurs during adolescence, most of the neural connections that are pruned contain receptors for glutamate or other excitatory neurotransmitters. Because of this, by early adulthood the synaptic balance in the brain is more inhibitory than excitatory. Dopamine is associated with pleasure and attuning to the environment during decision-making. During adolescence, dopamine levels in
2728-459: Is constructed via the choices and actions of an individual within the context of their historical period and social network. In 1984, the Society for Research on Adolescence (SRA) became the first official organization dedicated to the study of adolescent psychology. Some of the issues first addressed by this group include: the nature versus nurture debate as it pertains to adolescence; understanding
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2816-471: Is involved in decision making and cognitive control, as well as other higher cognitive functions. During adolescence, myelination and synaptic pruning in the prefrontal cortex increases, improving the efficiency of information processing, and neural connections between the prefrontal cortex and other regions of the brain are strengthened. This leads to better evaluation of risks and rewards, as well as improved control over impulses. Specifically, developments in
2904-545: Is less bound to concrete events than that of children: they can contemplate possibilities outside the realm of what currently exists. One manifestation of the adolescent's increased facility with thinking about possibilities is the improvement of skill in deductive reasoning , which leads to the development of hypothetical thinking. This provides the ability to plan ahead, see the future consequences of an action and to provide alternative explanations of events. It also makes adolescents more skilled debaters, as they can reason against
2992-410: Is more adult-like. Breast development will also be completed by this stage. In boys, four stages in development can be correlated with the curve of general body growth at adolescence. The initial sign of sexual maturation in boys usually is the "fat spurt". The maturing boy gains weight and becomes almost chubby, with a somewhat feminine fat distribution. This probably occurs because estrogen production by
3080-418: Is not limited to the limbic system: Several serotonin receptors have their gene expression change dramatically during adolescence, particularly in the human frontal and prefrontal cortex. Adolescence is a time of rapid cognitive development. Piaget describes adolescence as the stage of life in which the individual's thoughts start taking more of an abstract form and the egocentric thoughts decrease, allowing
3168-425: Is shaped by the period and location in which they grow up. The principle of the importance of timing in one's life refers to the different impact that life events have on development based on when in one's life they occur. The idea of linked lives states that one's development is shaped by the interconnected network of relationships of which one is a part and the principle of human agency asserts that one's life course
3256-428: Is the constructivist view of cognitive development. Based on the work of Piaget , it takes a quantitative, state-theory approach, hypothesizing that adolescents' cognitive improvement is relatively sudden and drastic. The second is the information-processing perspective , which derives from the study of artificial intelligence and attempts to explain cognitive development in terms of the growth of specific components of
3344-522: The American Psychological Association have shown that adolescents with a less privileged upbringing have a more difficult time developing their identity. The idea of self-concept is known as the ability of a person to have opinions and beliefs that are defined confidently, consistent and stable. Early in adolescence, cognitive developments result in greater self-awareness, greater awareness of others and their thoughts and judgments,
3432-518: The Great Depression and World War II , unique historical circumstances under which a generation of children grew up. The Oakland Growth Study, initiated by Harold Jones and Herbert Stolz in 1931, aimed to study the physical, intellectual, and social development of children in the Oakland area. Data collection began in 1932 and continued until 1981, allowing the researchers to gather longitudinal data on
3520-408: The gonads are formed. The general structure and shape of the body and face, as well as sex hormone levels, are similar in preadolescent boys and girls. As puberty begins and sex hormone levels rise, differences appear, though some changes are similar in males and females. Male levels of testosterone directly induce the growth of the genitals , and indirectly (via dihydrotestosterone (DHT))
3608-401: The limbic system increase and input of dopamine to the prefrontal cortex increases. The balance of excitatory to inhibitory neurotransmitters and increased dopamine activity in adolescence may have implications for adolescent risk-taking and vulnerability to boredom (see Cognitive development below). Serotonin is a neuromodulator involved in regulation of mood and behavior. Development in
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3696-401: The primary sex characteristics or sex organs . In the male, these are the penis , testes , scrotum . In the female, these are the ovaries , fallopian tubes , uterus , cervix , vagina and vulva . The primary sex organs are different from the secondary sex organs because at maturity they produce gametes , which are haploid male or female germ cells which can unite with another of
3784-485: The prostate . Estradiol and other hormones cause breasts to develop in females. However, fetal or neonatal androgens may modulate later breast development by reducing the capacity of breast tissue to respond to later estrogen . Underarm hair and pubic hair are usually considered secondary sex characteristics, but they may also be considered non-secondary sex characteristics because they are features of both sexes following puberty. In females, breasts are
3872-597: The roach Rutilus rutilus . Biologists today distinguish between "male-to-male combat" and "mate choice", usually female choice of male mates. Sexual characteristics due to combat are such things as antlers, horns, and greater size. Characteristics due to mate choice, often referred to as ornaments , include brighter plumage , coloration, and other features that have no immediate purpose for survival or combat. Male jumping spiders have visual patches of UV reflectance, which are ornamentations used to attract females. Sexual differentiation begins during gestation , when
3960-475: The sex organs . In males, the first stages of puberty involve growth of the testes and scrotum, followed by growth of the penis. At the time that the penis develops, the seminal vesicles , the prostate , and the bulbourethral gland also enlarge and develop. The first ejaculation of seminal fluid generally occurs about one year after the beginning of accelerated penis growth, although this is often determined culturally rather than biologically, since for many boys
4048-453: The British pediatrician who devised the categorization system. The human brain is not finished developing by the time a person reaches puberty, or even finishes it. The frontal lobe of the brain has been known to shape itself well into one's 30s. Neuroscientists often cannot agree precisely on when this developmental period ends or if there is an exact age for the end of brain development. Below
4136-562: The Freudian definition as a defense mechanism). Adolescents are much better able than children to understand that people do not have complete control over their mental activity. Being able to introspect may lead to two forms of adolescent egocentrism, which results in two distinct problems in thinking: the imaginary audience and the personal fable . These likely peak at age fifteen, along with self-consciousness in general. Related to metacognition and abstract thought , perspective-taking involves
4224-477: The Leydig cells in the testes is stimulated before the more abundant Sertoli cells begin to produce significant amounts of testosterone. During this stage, boys may appear obese and somewhat awkward physically. Approximately 1 year after the scrotum begins to increase in size, stage II can be seen. During this time, there is a redistribution of subcutaneous fat and the start of pubic hair growth. Following 8 to 12 months of
4312-702: The United States, bone density increases significantly more among black than white adolescents, which might account for decreased likelihood of black women developing osteoporosis and having fewer bone fractures there. Another set of significant physical changes during puberty happen in bodily distribution of fat and muscle. This process is different for females and males. Before puberty, there are nearly no sex differences in fat and muscle distribution; during puberty, boys grow muscle much faster than girls, although both sexes experience rapid muscle development. In contrast, though both sexes experience an increase in body fat,
4400-471: The ability to think about abstract, future possibilities, and the ability to consider multiple possibilities at once. As a result, adolescents experience a significant shift from the simple, concrete, and global self-descriptions typical of young children; as children, they defined themselves by physical traits whereas adolescents define themselves based on their values, thoughts, and opinions. Secondary sex characteristic A secondary sex characteristic
4488-510: The adolescent ages. The dual systems model proposes a maturational imbalance between development of the socioemotional system and cognitive control systems in the brain that contribute to impulsivity and other behaviors characteristic of adolescence. Some studies like the ABCD Study are researching on the baseline of adolescent cognitive development. There are at least two major approaches to understanding cognitive change during adolescence. One
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#17328848339004576-480: The advantage in capturing the attention of potential partners and in being picked first for sports. Pubescent boys often tend to have a good body image, are more confident, secure, and more independent. Late maturing boys can be less confident because of poor body image when comparing themselves to already developed friends and peers. However, early puberty is not always positive for boys; early sexual maturation in boys can be accompanied by increased aggressiveness due to
4664-432: The age of about roughly 30, the human brain has been implicated in human behavior and social immaturity. However, there has been no empirical study indicating a causal relationship with the development of the prefrontal cortex in adolescence and into early adulthood with any irrational behaviors. The brain reaches 90% of its adult size by six years of age. Thus, the brain does not grow in size much during adolescence. Over
4752-618: The article's talk page . Teenage Adolescence (from Latin adolescere 'to mature') is a transitional stage of physical and psychological development that generally occurs during the period from puberty to adulthood (typically corresponding to the age of majority ). Adolescence is usually associated with the teenage years, but its physical, psychological or cultural expressions may begin earlier or end later. Puberty typically begins during preadolescence , particularly in females. Physical growth (particularly in males) and cognitive development can extend past
4840-476: The article's talk page . This article relating to a British magazine connected with culture is a stub . You can help Misplaced Pages by expanding it . See tips for writing articles about magazines . Further suggestions might be found on the article's talk page . This European lifestyle magazine or journal-related article is a stub . You can help Misplaced Pages by expanding it . See tips for writing articles about magazines . Further suggestions might be found on
4928-422: The beginning of rapid growth, there is the development of breast buds and pubic hair. The peak period of physical growth occurs approximately one year later in concert with stage two of sexual maturity. Approximately 1 to 1.6 years after the onset of secondary sex characteristics, girls enter into the third stage which typically includes menarche. By this time, they will have finished their growth spurt and experience
5016-435: The body to behave in a certain way once puberty begins, and an active role, referring to changes in hormones during adolescence that trigger behavioral and physical changes. Puberty occurs through a long process and begins with a surge in hormone production, which in turn causes a number of physical changes. It is the stage of life characterized by the appearance and development of secondary sex characteristics (for example,
5104-399: The brain are noted to be mature by 14 or 15, making 'maturity' hard to define and has often been disagreed with. Prefrontal cortex pruning has been recorded to level off by age 14 or 15, and has been seen to continue as late as into the sixth decade of life. White matter is recorded to increase up until around the age of 45, and then it is lost via progressive aging. Adolescents' thinking
5192-506: The chin and the upper lip, adult distribution and color of pubic and axillary hair, and a further increase in muscular strength. The adolescent growth spurt is a rapid increase in the individual's height and weight during puberty resulting from the simultaneous release of growth hormones, thyroid hormones , and androgens . Males experience their growth spurt about two years later, on average, than females. During their peak height velocity (the time of most rapid growth), adolescents grow at
5280-473: The course of adolescence, the amount of white matter in the brain increases linearly, while the amount of grey matter in the brain follows an inverted-U pattern. Through a process called synaptic pruning , unnecessary neuronal connections in the brain are eliminated and the amount of grey matter is pared down. However, this does not mean that the brain loses functionality; rather, it becomes more efficient due to increased myelination (insulation of axons) and
5368-403: The dichotomy between identity formation and role fulfillment. Even with their different theories, these three psychologists agreed that adolescence was inherently a time of disturbance and psychological confusion. The less turbulent aspects of adolescence, such as peer relations and cultural influence, were left largely ignored until the 1980s. From the '50s until the '80s, the focus of the field
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#17328848339005456-408: The dorsolateral prefrontal cortex are important for controlling impulses and planning ahead, while development in the ventromedial prefrontal cortex is important for decision making. Changes in the orbitofrontal cortex are important for evaluating rewards and risks. Three neurotransmitters that play important roles in adolescent brain development are glutamate , dopamine and serotonin . Glutamate
5544-586: The family circle, they learn that rules they were taught as absolute are in fact relativistic. They begin to differentiate between rules instituted out of common sense—not touching a hot stove—and those that are based on culturally relative standards (codes of etiquette, not dating until a certain age), a delineation that younger children do not make. This can lead to a period of questioning authority in all domains. Because most injuries sustained by adolescents are related to risky behavior (alcohol consumption and drug use, reckless or distracted driving, unprotected sex),
5632-403: The first ejaculation occurs as a result of masturbation. Boys are generally fertile before they have an adult appearance. In females, changes in the primary sex characteristics involve growth of the uterus, vagina, and other aspects of the reproductive system. Menarche , the beginning of menstruation, is a relatively late development which follows a long series of hormonal changes. Generally,
5720-425: The future. This phenomenon also has consequences for behavioral treatments based on the principle of extinction, such as cue exposure therapy for anxiety or drug addiction. It has been suggested that impaired inhibition, specifically extinction, may help to explain adolescent propensity to relapse to drug-seeking even following behavioral treatment for addiction. The formal study of adolescent psychology began with
5808-650: The increase is much more significant for girls. Frequently, the increase in fat for girls happens in their years just before puberty. The ratio between muscle and fat among post-pubertal boys is around three to one, while for girls it is about five to four. This may help explain sex differences in athletic performance. Pubertal development also affects circulatory and respiratory systems as an adolescents' heart and lungs increase in both size and capacity. These changes lead to increased strength and tolerance for exercise. Sex differences are apparent as males tend to develop "larger hearts and lungs, higher systolic blood pressure,
5896-430: The individual to think and reason in a wider perspective. A combination of behavioural and fMRI studies have demonstrated development of executive functions , that is, cognitive skills that enable the control and coordination of thoughts and behaviour, which are generally associated with the prefrontal cortex . The thoughts, ideas and concepts developed at this period of life greatly influence one's future life, playing
5984-576: The individuals that extended past adolescence into adulthood. Jean Macfarlane launched the Berkeley Guidance Study, which examined the development of children in terms of their socioeconomic and family backgrounds. These studies provided the background for Glen Elder in the 1960s to propose a life course perspective of adolescent development. Elder formulated several descriptive principles of adolescent development. The principle of historical time and place states that an individual's development
6072-417: The interactions between adolescents and their environment; and considering culture, social groups, and historical context when interpreting adolescent behavior. Evolutionary biologists like Jeremy Griffith have drawn parallels between adolescent psychology and the developmental evolution of modern humans from hominid ancestors as a manifestation of ontogeny recapitulating phylogeny . Identity development
6160-430: The limbic system plays an important role in determining rewards and punishments and processing emotional experience and social information. Changes in the levels of the neurotransmitters dopamine and serotonin in the limbic system make adolescents more emotional and more responsive to rewards and stress. The corresponding increase in emotional variability also can increase adolescents' vulnerability. The effect of serotonin
6248-554: The manes of male lions , the bright facial and rump coloration of male mandrills , and horns in many goats and antelopes . Secondary sex characteristics are particularly evident in the sexually dimorphic phenotypic traits that distinguish the sexes of a species. In evolution, secondary sex characteristics are the product of sexual selection for traits that show fitness , giving an organism an advantage over its rivals in courtship and in aggressive interactions. Many characteristics are believed to have been established by
6336-451: The number of grandchildren they produce. An alternative hypothesis is that some of the genes that enable males to develop impressive ornaments or fighting ability may be correlated with fitness markers such as disease resistance or a more efficient metabolism . This idea is known as the good genes hypothesis . Examples of secondary sex characteristics in non-human animals include manes of male lions and long feathers of male peafowl ,
6424-604: The opposite sex during sexual reproduction to form a zygote . The secondary sex characteristics differ in that they will not be identifiable at birth , they will develop as the subject becomes sexually mature . In mammals, these characteristics include breasts in females and greater muscle mass in males. Secondary sexual characteristics have an evolutionary purpose: increase the chance of breeding. In The Descent of Man and Selection in Relation to Sex , Charles Darwin hypothesized that sexual selection , or competition within
6512-407: The peak velocity in height gain, stage III ensues. This period is marked by an obvious widenening of hips with a more adult-like fat distribution and full development of the breasts. All together, these three stages culminate in a complete growth spurt for most individuals. At this time, axillary hair appears and facial hair appears on the upper lip only. A spurt in muscle growth also occurs, along with
6600-417: The post-pubertal age is uncommon. Girls attain reproductive maturity about four years after the first physical changes of puberty appear. In contrast, boys develop more slowly but continue to grow for about six years after the first visible pubertal changes. The physical development of girls during their teenage years can be broken down into three distinct stages. At the start, which generally coincides with
6688-486: The potential rewards and consequences of an action. However, research has shown that adolescents seem to give more weight to rewards, particularly social rewards, than do adults. Research seems to favor the hypothesis that adolescents and adults think about risk in similar ways, but hold different values and thus come to different conclusions. Some have argued that there may be evolutionary benefits to an increased propensity for risk-taking in adolescence. For example, without
6776-489: The publication of G. Stanley Hall 's Adolescence in 1904. Hall, who was the first president of the American Psychological Association , defined adolescence to be the period of life from ages 14 to 24, and viewed it primarily as a time of internal turmoil and upheaval ( sturm und drang ). This understanding of youth was based on two then-new ways of understanding human behavior : Darwin's evolutionary theory and Freud's psychodynamic theory . He believed that adolescence
6864-421: The reduction of unused pathways. The first areas of the brain to be pruned are those involving primary functions, such as motor and sensory areas. The areas of the brain involved in more complex processes lose matter later in development. These include the lateral and prefrontal cortices, among other regions. Some of the most developmentally significant changes in the brain occur in the prefrontal cortex, which
6952-477: The rest of the lower face to form a full beard. As with most human biological processes, this specific order may vary among some individuals. Facial hair is often present in late adolescence, around ages 17 and 18, but may not appear until significantly later. Some men do not develop full facial hair for 10 years after puberty. Facial hair continues to get coarser, much darker, and thicker for another 2–4 years after puberty. The major landmark of puberty for males
7040-532: The surge of hormones that affect them. Because they appear older than their peers, pubescent boys may face increased social pressure to conform to adult norms; society may view them as more emotionally advanced, despite the fact that their cognitive and social development may lag behind their appearance. Studies have shown that early maturing boys are more likely to be sexually active and are more likely to participate in risky behaviors. For girls, early maturation can sometimes lead to increased self-consciousness,
7128-470: The teens. Age provides only a rough marker of adolescence, and scholars have not agreed upon a precise definition. Some definitions start as early as 10 and end as late as 30. The World Health Organization definition officially designates an adolescent as someone between the ages of 10 and 19. Puberty is a period of several years in which rapid physical growth and psychological changes occur, culminating in sexual maturity. The average age of onset of puberty
7216-418: The thinking process. By the time individuals have reached ages 12–14 or so their critical thinking and decision-making competency are comparable to those of adults. These improvements occur in five areas during adolescence: Studies newer than 2005 indicate that the brain is changing in efficiency well past its twenties, a 'point of maturity' in the twenties is somewhat arbitrary as many important parts of
7304-555: The transition to adulthood. Researchers have used three general approaches to understanding identity development: self-concept, sense of identity, and self-esteem. The years of adolescence create a more conscientious group of young adults. Adolescents pay close attention and give more time and effort to their appearance as their body goes through changes. Unlike children, teens put forth an effort to look presentable (1991). The environment in which an adolescent grows up also plays an important role in their identity development. Studies done by
7392-521: The tusks of male narwhals , enlarged proboscises in male elephant seals and proboscis monkeys , the bright facial and rump coloration of male mandrills , horns in many goats and antelopes , and the swollen upper lip and elongated premaxillary and maxillary teeth of male spikethumb frogs . Male fish develop " nuptial tubercles ", mainly on their snouts, in the breeding season. These are an honest signal of health, and may assist females in sexual selection for species that use lek mating , such as
7480-448: The voice, roughening of the skin around the upper arms and thighs, and increased development of the sweat glands. In females, secondary sex changes involve elevation of the breasts, widening of the hips, development of pubic and underarm hair, widening of the areolae, and elevation of the nipples. The changes in secondary sex characteristics that take place during puberty are often referred to in terms of five Tanner stages , named after
7568-492: The ways in which language can be used to convey multiple messages, such as satire, metaphor, and sarcasm . (Children younger than age nine often cannot comprehend sarcasm at all.) This also permits the application of advanced reasoning and logical processes to social and ideological matters such as interpersonal relationships, politics, philosophy, religion, morality, friendship, faith, fairness, and honesty. A third gain in cognitive ability involves thinking about thinking itself,
7656-428: Was a representation of our human ancestors' phylogenetic shift from being primitive to being civilized. Hall's assertions stood relatively uncontested until the 1950s when psychologists such as Erik Erikson and Anna Freud started to formulate their theories about adolescence. Freud believed that the psychological disturbances associated with youth were biologically based and culturally universal while Erikson focused on
7744-569: Was mainly on describing patterns of behavior as opposed to explaining them. Jean Macfarlane founded the University of California, Berkeley 's Institute of Human Development, formerly called the Institute of Child Welfare, in 1927. The institute was instrumental in initiating studies of healthy development, in contrast to previous work that had been dominated by theories based on pathological personalities. The studies looked at human development during
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