Editing Adolescence (section)

===Puberty in general===
{{Main|Puberty}}
[[File:Cubes teenager.jpg|thumb|left|Upper body of a teenage boy. The structure has changed to resemble an [[adult]] form.]]
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 is 10–11 for girls and 11–12 for boys.<ref name=Kail>{{cite book| last = Kail | first = RV |author2=Cavanaugh JC | title = Human Development: A Lifespan View | isbn = 978-0-495-60037-4 | publisher = [[Cengage Learning]] | year = 2010|access-date= September 11, 2014| page = 296 | edition = 5th|url=https://books.google.com/books?id=E-n5E7oyCgoC&pg=PA296}}</ref><ref name="PAmf.org">{{Cite news|title=Teenage Growth & Development: 11 to 14 Years|publisher=[[Palo Alto Medical Foundation]]|url=http://www.pamf.org/teen/parents/health/growth-11-14.html|quote=For girls, puberty begins around 10 or 11 years of age and ends around age 16. Boys enter puberty later than girls-usually around 12 years of age-and it lasts until around age 16 or 17.}}</ref> Every person's individual timetable for puberty is influenced primarily by [[heredity]], although environmental factors, such as diet and exercise, also exert some influences.<ref name=Tanner/><ref name=Kaplowitz01>{{Cite journal|doi=10.1542/peds.108.2.347 |vauthors=Kaplowitz PB, Slora EJ, Wasserman RC, Pedlow SE, Herman-Giddens ME |title=Earlier onset of puberty in girls: relation to increased body mass index and race |journal=Pediatrics |volume=108 |issue=2 |pages=347–53 |date=August 2001 |pmid=11483799 |url=http://pediatrics.aappublications.org/cgi/pmidlookup?view=long&pmid=11483799}}</ref> These factors can also contribute to [[precocious puberty|precocious]] and [[delayed puberty]].<ref name="Delayed puberty">{{cite web|first=Elizabeth|last=Cooney|title=Puberty gap: Obesity splits boys, girls. Adolescent males at top of the BMI chart may be delayed|work=[[NBC News]]|date=February 11, 2010|access-date=May 22, 2010|url=http://www.nbcnews.com/id/35332881|archive-date=January 11, 2016|archive-url=https://web.archive.org/web/20160111055843/http://www.nbcnews.com/id/35332881|url-status=dead}}</ref><ref name=Kaplowitz01/>

Some of the most significant parts of pubertal development involve distinctive physiological changes in individuals' height, weight, body composition, and [[circulatory system|circulatory]] and [[respiratory system|respiratory]] systems.<ref>Marshal, W. (1978). Puberty. In F. Falkner & J.Tanner (Eds.), ''Human growth'', Vol. 2. New York: Plenum.</ref> These changes are largely influenced by hormonal activity. [[Hormones]] play an organizational role, priming the body to behave in a certain way once puberty begins,<ref>{{cite journal |last1=Sisk |first1=Cheryl L |last2=Foster |first2=Douglas L |title=The neural basis of puberty and adolescence |journal=Nature Neuroscience |date=October 2004 |volume=7 |issue=10 |pages=1040–1047 |doi=10.1038/nn1326 |pmid=15452575 |s2cid=2932858 }}</ref> and an active role, referring to changes in hormones during adolescence that trigger behavioral and physical changes.<ref>{{cite book |last1=Coe |first1=Christopher L. |last2=Hayashi |first2=Kevin T. |last3=Levine |first3=Seymour |chapter=Hormones and Behavior at Puberty: Activation or Concatenation |pages=17–41 |chapter-url=https://books.google.com/books?id=w_J1oKCvCMEC&pg=PA17 |editor1-last=Gunnar |editor1-first=Megan R. |editor2-last=Collins |editor2-first=W. Andrew |title=Development During the Transition to Adolescence |date=1988 |publisher=Psychology Press |isbn=978-0-8058-0194-1 }}</ref>

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 characteristic]]s (for example, a deeper voice and larger [[Adam's apple]] in boys, and development of [[breast]]s 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 [[Hormone|hormonal]] agents into the blood stream, initiating a chain reaction. The male and female [[gonads]] are thereby activated, which puts them into 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 hormone]]s, tissue responsiveness or [[obesity]].<ref>{{Cite journal|vauthors=Nydick M, Bustos J, Dale JH, Rawson RW |title=Gynecomastia in adolescent boys |journal=JAMA |volume=178 |issue= 5|pages=449–54 |date=November 1961 |pmid=14480779|doi=10.1001/jama.1961.03040440001001 }}</ref>

[[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 and 17 years of age.<ref name="pamf.org">{{Cite news|title=Puberty – Changes for Males|publisher=pamf.org|access-date=February 20, 2009 |url=http://www.pamf.org/teen/health/puberty/physicalchanges.html| archive-url= https://web.archive.org/web/20090303201905/http://www.pamf.org/teen/health/puberty/physicalchanges.html| archive-date= March 3, 2009 | url-status= live}}</ref><ref name="www.ppwr">{{cite web|title=Getting The Facts: Puberty|publisher=ppwr|access-date=February 20, 2009|url=http://www.ppwr.on.ca/03_07.html|archive-url=https://web.archive.org/web/20090226191204/http://www.ppwr.on.ca/03_07.html|archive-date=February 26, 2009|url-status=dead}}</ref> 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.<ref name="pamf.org"/> 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.<ref name="pamf.org"/> 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.<ref name="www.ppwr"/><ref name="pbskids.org">{{Cite news|title=The No-Hair Scare|publisher=[[PBS]]|access-date=February 20, 2009|url=http://pbskids.org/itsmylife/body/puberty/article7.html|archive-url=https://web.archive.org/web/20090205115944/http://pbskids.org/itsmylife/body/puberty/article7.html|archive-date=February 5, 2009|url-status=dead}}</ref> Some men do not develop full facial hair for 10 years after puberty.<ref name="www.ppwr"/> Facial hair continues to get coarser, much darker, and thicker for another 2–4 years after puberty.<ref name="www.ppwr"/>

The major landmark of puberty for males is [[spermarche]], the first [[ejaculation]], which occurs, on average, at age 13.<ref name="Jorgensen & Keiding">(Jorgensen & Keiding 1991).{{full citation needed|date=October 2022}}</ref> For females, it is [[menarche]], the onset of menstruation, which occurs, on average, between ages 12 and 13.<ref name="Tanner">(Tanner, 1990).{{full citation needed|date=October 2022}}</ref><ref name="U.S. menarche">{{cite journal |vauthors=Anderson SE, Dallal GE, Must A |title=Relative weight and race influence average age at menarche: results from two nationally representative surveys of US girls studied 25 years apart |journal=Pediatrics |volume=111 |issue=4 Pt 1 |pages=844–50 |date=April 2003 |pmid=12671122 |doi=10.1542/peds.111.4.844}}</ref><ref name="Canadian menarche">{{cite journal |title=Age at menarche in Canada: results from the National Longitudinal Survey of Children & Youth|year= 2010 |pmid=21110899 |doi=10.1186/1471-2458-10-736 |pmc=3001737 |volume=10 |journal=BMC Public Health |page=736 |vauthors=Al-Sahab B, Ardern CI, Hamadeh MJ, Tamim H |issue=1 |doi-access= free }}</ref><ref name="UK menarche">{{cite journal |url=http://vstudentworld.yolasite.com/resources/final_yr/gynae_obs/Hamilton%20Fairley%20Obstetrics%20and%20Gynaecology%20Lecture%20Notes%202%20Ed.pdf |title=Obstetrics and Gynaecology |first=Diana |last=Hamilton-Fairley |edition=Second |publisher=Blackwell Publishing |journal= |access-date=December 9, 2011 |archive-date=October 9, 2018 |archive-url=https://web.archive.org/web/20181009065351/http://vstudentworld.yolasite.com/resources/final_yr/gynae_obs/Hamilton%20Fairley%20Obstetrics%20and%20Gynaecology%20Lecture%20Notes%202%20Ed.pdf |url-status=dead }}</ref> The age of menarche is influenced by heredity, but a girl's diet and lifestyle contribute as well.<ref name=Tanner/> Regardless of genes, a girl must have a certain proportion of body fat to attain menarche.<ref name=Tanner/> 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).<ref name=Tanner/><ref name=Kaplowitz01/> Girls who experience malnutrition or are in societies in which children are expected to perform physical labor also begin menstruating at later ages.<ref name=Tanner/>

The timing of puberty can have important psychological and social consequences. Early maturing boys are usually taller and stronger than their friends.<ref name=abbassi1998>{{Cite journal|author=Abbassi V |title=Growth and normal puberty |journal=Pediatrics |volume=102 |issue=2 Pt 3 |pages=507–11 |year=1998 |doi=10.1542/peds.102.S3.507 |pmid=9685454 |s2cid=24733669 }}</ref> They have 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.<ref name="Garn">{{cite journal |last1=Garn |first1=Stanley Marion |title=Physical growth and development |journal=American Journal of Physical Anthropology |date=June 1952 |volume=10 |issue=2 |pages=169–192 |doi=10.1002/ajpa.1330100215 |pmid=14952566 }}</ref> 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.<ref name=Garn/> 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 [[Cognition|cognitive]] and [[Social change|social development]] may lag behind their appearance.<ref name=Garn/> Studies have shown that early maturing boys are more likely to be sexually active and are more likely to participate in risky behaviors.<ref name=Susman>{{cite book |doi=10.1002/0471264385.wei0612 |chapter=Puberty, Sexuality, and Health |title=Handbook of Psychology |year=2003 |last1=Susman |first1=Elizabeth J. |last2=Dorn |first2=Lorah D. |last3=Schiefelbein |first3=Virginia L. |isbn=978-0-471-26438-5 |chapter-url=https://books.google.com/books?id=odIVt4_OGqcC&pg=PA295 |pages=295–324 |editor1-last=Weiner |editor1-first=Irving B. |editor2-last=Freedheim |editor2-first=Donald K. |editor3-last=Lerner |editor3-first=Richard M. |editor4-last=Easterbrooks |editor4-first=M. Ann |editor5-last=Mistry |editor5-first=Jayanthi }}</ref>

For girls, early maturation can sometimes lead to increased self-consciousness, a typical aspect in maturing females.<ref name="Pamf.org">{{Cite news|title=Teenage Growth & Development: 15 to 17 Years|publisher=[[Palo Alto Medical Foundation]]|access-date=February 20, 2009 |url=http://www.pamf.org/teen/parents/health/growth-15-17.html| archive-url= https://web.archive.org/web/20090226174419/http://www.pamf.org/teen/parents/health/growth-15-17.html| archive-date= February 26, 2009 | url-status= live}}</ref> Because of their bodies' developing in advance, pubescent girls can become more insecure and dependent.<ref name="Pamf.org"/> Consequently, girls that reach sexual maturation early are more likely than their peers to develop [[eating disorder]]s (such as [[anorexia nervosa]]). Nearly half of all American high school girls' diets are to lose weight.<ref name="Pamf.org"/> In addition, girls may have to deal with sexual advances from older boys before they are emotionally and mentally mature.<ref>(Peterson, 1987).{{full citation needed|date=October 2022}}</ref> In addition to having earlier sexual experiences and more unwanted pregnancies than late maturing girls, early maturing girls are more exposed to [[Alcoholic beverage|alcohol]] and [[drug abuse]].<ref>Caspi et al.1993{{full citation needed|date=October 2022}}</ref><ref>Lanza and Collins, 2002{{full citation needed|date=October 2022}}</ref> Those who have had such experiences tend to not perform as well in school as their "inexperienced" peers.<ref>{{cite book |last1=Stattin |first1=Håkan |title=Pubertal Maturation in Female Development |last2=Magnusson |first2=David |year=2018 |isbn=978-1-315-78901-9 |page=25 |doi=10.4324/9781315789019 |s2cid=143088283}}</ref>

Girls have usually reached full physical development around ages 15–17,<ref name="MedlinePlus archive 001950 Puberty and adolescence"/><ref name="PAmf.org"/><ref name="PAMf.org">{{Cite news|title=Teenage Growth & Development: 15 to 17 Years|publisher=[[Palo Alto Medical Foundation]]|url=http://www.pamf.org/teen/parents/health/growth-15-17.html}}</ref> while boys usually complete puberty around ages 16–17.<ref name="PAmf.org"/><ref name="PAMf.org"/><ref name="Marshall17677">Marshall (1986), p. 176–7</ref> Any increase in height beyond the post-pubertal age is uncommon. Girls attain reproductive maturity about four years after the first physical changes of puberty appear.<ref name="MedlinePlus archive 001950 Puberty and adolescence"/> In contrast, boys develop more slowly but continue to grow for about six years after the first visible pubertal changes.<ref name="Garn"/><ref name="Marshall17677"/>

[[File:Child development stages.svg|thumb|center|800px|Approximate outline of development periods in [[child development|childhood]] and early adulthood development. Adolescence is marked in red at top right.]]