Adolescence (from Latin: adolescere meaning “to grow up”) is a transitional stage of physical and mental human development generally occurring between puberty and legal adulthood (age of majority), but largely characterized as beginning and ending with the teenage stage.  According to Erik Erikson’s stages of human development, for example, a young adult is generally a person between the ages of 20 and 40, whereas an adolescent is a person between the ages of 13 and 19. 3] Historically, puberty has been heavily associated with teenagers and the onset of adolescent development.  However, the start of puberty has had somewhat of an increase in preadolescence (particularly females, as seen with early and precocious puberty), and adolescence has had an occasional extension beyond the teenage years (typically males) compared to previous generations. These changes have made it more difficult to rigidly define the time frame in which adolescence occurs. 
The end of adolescence and the beginning of adulthood varies by country and by function, and furthermore even within a single nation-state or culture there can be different ages at which an individual is considered to be (chronologically and legally) mature enough to be entrusted by society with certain tasks. Such milestones include, but are not limited to, driving a vehicle, having legal sexual relations, serving in the armed forces or on a jury, purchasing and drinking alcohol, voting, entering into contracts, completing certain levels of education, and marrying.
Adolescence is usually accompanied by an increased independence allowed by the parents or legal guardians and less supervision, contrary to the preadolescence stage. Contents [hide] 1 History 2 Puberty 3 Psychology 4 Sexuality 5 Culture 6 Legal issues, rights and privileges 7 See also 7. 1 Human development and psychology 7. 1. 1 Compare with 7. 2 Literature 8 References  History In many societies, adolescence was not recognized as a phase of life. Most societies simply distinguished between childhood and adulthood.
Stanley Hall is generally credited with “discovering” adolescence with his 1904 study “Adolescence” in which he describes the developmental phase now recognized as adolescence. Hall attributed the new stage to social changes at the turn of the 20th century. Child labor laws kept individuals under 16 out of the work force, and universal education laws kept them in secondary school, thus prolonging the period of dependence — a dependence that allowed them to address psychological tasks they might have ignored when they took on adult roles straight out of childhood. 11]  Puberty Upper body of teenage boy. The structure has changed to resemble an adult form. Main article: Puberty Puberty is a period of several years in which rapid physical growth and psychological changes occur, culminating in sexual maturity. The average onset of puberty is at 10 for girls and age 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 influence. 12] These factors can also contribute to precocious puberty and delayed puberty.  Puberty begins with a surge in hormone production, which in turn causes a number of physical changes.  It is also the stage of life in which a child develops secondary sex characteristics (for example, a deeper voice and larger adam’s apple in boys, and development of breasts and more curved and prominent hips in girls) as his or her hormonal balance shifts strongly towards an adult state. This is triggered by the pituitary gland, which ecretes a surge of hormonal agents into the blood stream, initiating a chain reaction. The male and female gonads are subsequently activated, which puts them into a state of rapid growth and development; the triggered gonads now commence the mass production of the necessary chemicals. 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 a specific order during puberty: The first facial hair to appear tends to grow at the corners of the upper lip, typically between 14 to 16 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 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 will continue to get coarser, darker and thicker for another 2–4 years after puberty.  The major landmark of puberty for males is 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. 13] Regardless of genes, a girl must have certain proportion of body fat to attain menarche.  Consequently, girls who have 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 the advantage in capturing the attention of potential partners and in becoming hand-picked 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 the surge of hormones that affect them. 22] 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, though a typical aspect in maturing females. 24] Because of their bodies developing in advance, pubescent girls can become more insecure.  Consequently, girls that reach sexual maturation early are more likely than their peers to develop eating disorders. Nearly half of all American high school girls’ diet is 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. 26] Those who have had such experiences tend to perform less well in school than their “inexperienced” age peers.  Girls have usually reached full physical development by ages 15–17, while boys usually complete puberty by ages 16–18.  Any increase in height beyond these ages is uncommon. Girls attain reproductive maturity about 4 years after the first physical changes of puberty appear.  In contrast, boys accelerate more slowly but continue to grow for about 6 years after the first visible pubertal changes. 22]
Teenage and early adult males may continue to gain natural muscle growth even after puberty.  Approximate outline of development periods in child and teenager development. Adolescence is marked in red at top right.  Psychology Main article: Adolescent psychology Expressed hostile attitude of a teenage girl. Adolescence is characterized by a number of cognitive, emotional, physical and attitudinal changes, which can be a cause of conflict on one hand and positive personality development on the other. The home environment and parents are still important for the behaviors and choices of adolescents. 32] Adolescents who have a good relationship with their parents are less likely to engage in various risk behaviors, such as smoking, drinking, fighting, and/or sexual intercourse.  In conflict with their parents, adolescents are more flexible than younger children, but more hostile and rigid compared to adults. The topics of conflicts between adolescents and their parents are often about the extent to which parents can control and supervise the adolescent, for instance conflicts about chores, schoolwork, curfew, and the adolescent’s right to privacy. 33] For the first time in their lives adolescents may start to view their friends, their peer group, as more important and influential than their parents or guardians.  Peer groups offer its members the opportunity to develop various social skills, such as empathy, sharing and leadership.
Peer groups can have positive influences on an individual, for instance on academic motivation and performance, but they can also have negative influences and lead to an increase in experimentation with drugs, drinking, vandalism, and stealing. 35] Susceptibility to peer pressure increases during early adolescence, peaks around age 14, and declines thereafter.  In the search for a unique social identity for themselves, adolescents are frequently confused about what is ‘right’ and what is ‘wrong. ‘ G. Stanley Hall denoted this period as one of “Storm and Stress” and, according to him, conflict at this developmental stage is normal and not unusual. Margaret Mead, on the other hand, attributed the behavior of adolescents to their culture and upbringing. 
Adolescence is also a time for 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. This allows 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. 40] The thoughts, ideas and concepts developed at this period of life greatly influence one’s future life, playing a major role in character and personality formation.  Adolescent psychology is associated with notable changes in mood sometimes known as mood swings.  Positive psychology is sometimes brought up when addressing adolescent psychology as well. This approach towards adolescents refers to providing them with motivation to become socially acceptable and notable individuals, since many adolescents find themselves bored, indecisive and/or unmotivated. 
Struggles with adolescent identity and depression usually set in when an adolescent experiences a loss. The most important loss in their lives is the changing relationship between the adolescent and their parents. Adolescents may also experience strife in their relationships with friends. This may be due to the activities their friends take part in, such as smoking, which causes adolescents to feel as though participating in such activities themselves is likely essential to maintaining these friendships. Teen depression can be extremely intense at times because of physical and hormonal changes but emotional instability is part of adolescence.
Their changing mind, body and relationships often present themselves as stressful and that change, they assume, is something to be feared.  Sleep deprivation has also been linked to adolescent depression, particularly in the teen years.  Views of family relationships during adolescence are changing. The old view of family relationships during adolescence put an emphasis on conflict and disengagement and thought storm and stress was normal and even inevitable. However, the new view puts emphasis on transformation or relationships and maintenance of connectedness.  edit] Sexuality Main article: Adolescent sexuality Adolescent sexuality refers to sexual feelings, behavior and development in adolescents and is a stage of human sexuality. Sexuality and sexual desire usually begins to intensify along with the onset of puberty. The expression of sexual desire among adolescents (or anyone, for that matter), might be influenced by family values and the culture and religion they have grown up in (or as a backlash to such), social engineering, social control, taboos, and other kinds of social mores. Teenage couples at a fair in the American West.
In contemporary society, adolescents also face some risks as their sexuality begins to transform. Whilst some of these such as emotional distress (fear of abuse or exploitation) and sexually transmitted diseases (including HIV/AIDS) may not necessarily be inherent to adolescence, others such as pregnancy (through non-use or failure of contraceptives) are seen as social problems in most western societies. In terms of sexual identity, while all sexual orientations found in adults are also represented among adolescents, statistically the suicide rate amongst LGBT adolescents is up to four times higher than that of their heterosexual peers. 45] According to anthropologist Margaret Mead and psychologist Albert Bandura, the turmoil found in adolescence in Western society has a cultural rather than a physical cause; they reported that societies where young women engaged in free sexual activity had no such adolescent turmoil. In a 2008 study conducted by YouGov for Channel 4, 20% of 14? 17-year-olds surveyed revealed that they had their first sexual experience at 13 or under.  Another study from 2002 found that those aged 15–44 reported that the average age of first sexual intercourse was 17. for males and 17. 3 for females.  The age of consent to sexual activity varies widely between international jurisdictions, ranging from 12 to 21 years.   Culture Main article: Youth subculture In commerce, this generation[clarification needed] is seen as an important target. Mobile phones, contemporary popular music, movies, television programs, websites, sports, video games and clothes are heavily marketed and often popular amongst adolescents. In the past (and still in some cultures) there were ceremonies that celebrated adulthood, typically occurring during adolescence.
Seijin shiki (literally “adult ceremony”) is a Japanese example of this. Upanayanam is a coming of age ceremony for males in the Hindu world. In Judaism, 13-year-old boys and 12-year-old girls become Bar or Bat Mitzvah, respectively, and often have a celebration to mark this coming of age. Among some denominations of Christianity, the rite or sacrament of Confirmation is received by adolescents and may be considered the time at which adolescents become members of the church in their own right (there is also a Confirmation ceremony in some Reform Jewish temples, although the bar or bat mitzvah ceremony appears to have precedence).
In United States, girls will often have a “sweet sixteen” party to celebrate turning the aforementioned age, a tradition similar to the quinceanera in Latin culture. In modern western society, events such as getting your first driver’s license, high school and later on college graduation and first career related job are thought of as being more significant markers in transition to adulthood. Adolescents have also been an important factor in many movements for positive social change around the world.
The popular history of adolescents participating in these movements may perhaps start with Joan of Arc, and extend to present times with popular youth activism, student activism, and other efforts to make the youth voice heard.  Legal issues, rights and privileges Internationally, those who reach a certain age (often 18, though this varies) are legally considered to have reached the age of majority and are regarded as adults and are held to be responsible for their actions. People below this age are considered minors or children.
A person below the age of majority may gain adult rights through legal emancipation. Those who are under the age of consent, or legal responsibility, may be considered too young to be held accountable for criminal action. This is called doli incapax or the defense of infancy. The age of criminal responsibility varies from 7 in India to 18 in Belgium. After reaching the initial age, there may be levels of responsibility dictated by age and type of offense, and crimes committed by minors may be tried in a juvenile court.
The legal working age in Western countries is usually 14 to 16, depending on the number of hours and type of employment. In the United Kingdom and Canada, for example, young people between 14 and 16 can work at certain types of light work with some restrictions to allow for schooling; while youths over 16 can work full-time (excluding night work). Many countries also specify a minimum school leaving age, ranging from 10 to 18, at which a person is legally allowed to leave compulsory education.
The age of consent to sexual activity varies widely between jurisdictions, ranging from 13 to 21 years, the average age is 16.  In a 2008 study of 14 to 17-year-olds conducted by YouGov for Channel 4, it was revealed that one in three 15-year-olds were sexually active.  Sexual intercourse with a person below the local age of consent is usually treated as the crime of statutory rape. Some jurisdictions allow an exemption where both partners are close in age; for example, a 16-year-old and an 18-year-old.
The age at which people are allowed to marry also varies, from 17 in Yemen to 22 for males and 20 for females in China. In Western countries, people are typically allowed to marry at 18, although they are sometimes allowed to marry at a younger age with parental or court consent. In developing countries, the legal marriageable age does not always correspond with the age at which people actually marry; for example, the legal age for marriage in Ethiopia is 18 for both males and females, but in rural areas most girls are married by age 16.
In most democratic countries, a citizen is eligible to vote at 18. For example, in the United States, the Twenty-sixth amendment decreased the voting age from 21 to 18. In a minority of countries, the voting age is 17 (for example, Indonesia) or 16 (for example, Brazil). By contrast, some countries have a minimum voting age of 21 (for example, Singapore) whereas the minimum age in Uzbekistan is 25. Age of candidacy is the minimum age at which a person can legally qualify to hold certain elected government offices.
In most countries, a person must be 18 or over to stand for elected office, but some countries such as the United States and Italy have further restrictions depending on the type of office. A sign outside a sex shop reads “Must Be 18 To Enter” in Chapel Hill, North Carolina. The sale of selected items such as cigarettes, alcohol, and videos with violent or pornographic content is also restricted by age in most countries. In the U. S, the minimum age to buy an R-rated movie, M-rated game or an album with a parental advisory label is 17 (in some states 18 or even 21).
In practice, it is common that young people engage in underage smoking or drinking, and in some cultures this is tolerated to a certain degree. In the United States, teenagers are allowed to drive between 14–18 (each state sets its own minimum driving age of which a curfew may be imposed), in the US, adolescents 17 years of age can serve in the military. In Europe it is more common for the driving age to be higher (usually 18) while the drinking age is lower than that of the US (usually 16 or 18).
In Canada, the drinking age is 18 in some areas and 19 in other areas. In Australia, universally the minimum drinking age is 18, unless a person is in a private residence or is under parental supervision in a licensed premises. The driving age varies from state to state but the more common system is a graduated system of “L plates” (a learning license that requires supervision from a licensed driver) from age 16, red “P plates” (probationary license) at 17, green “P plates” at 18 and finally a full license, i. e. for most people around the age of 20.
The legal gambling age also depends on the jurisdiction, although it is typically 18. The minimum age for donating blood in the U. S is 17 although it may be 16 with parental permission in some states such as New York, New Jersey, Wisconsin, and Pennsylvania.  Suitable age and discretion is a legal definition of maturity.  A number of social scientists, including anthropologist Margaret Mead and sociologist Mike Males, have noted the contradictory treatment of laws affecting adolescents in the United States.
As Males has noted, the US Supreme Court has, “explicitly ruled that policy-makers may impose adult responsibilities and punishments on individual youths as if they were adults at the same time laws and policies abrogate adolescents’ rights en masse as if they were children. “ The issue of youth activism affecting political, social, educational, and moral circumstances is of growing significance around the world. Youth-led organizations around the world have fought for social justice, the youth vote seeking to gain teenagers the right to vote, to secure more youth rights, and demanding better schools through student activism.
Since the advent of the Convention on the Rights of the Child in 1989 (children defined as under 18), almost every country (except the U. S. ; Somalia) in the world has become voluntarily legally committed to advancing an anti-discriminatory stance towards young people of all ages. This is a legally binding document which secures youth participation throughout society while acting against unchecked child labor, child soldiers, child prostitution, and pornography.