Editing Adult (section)

==Biological adulthood==
Historically and cross-culturally, adulthood has been determined primarily by the start of [[puberty]] (the appearance of [[secondary sex characteristics]] such as [[menstruation]] and the development of breasts in women, [[ejaculation]], the development of facial hair, and a deeper voice in men, and pubic hair in both sexes).<ref name="McNamara">{{Cite book |last=McNamara |first=Thomas Edward |url=https://books.google.com/books?id=BeLmG7HP_U0C&pg=PA262 |title=Evolution, Culture, and Consciousness: The Discovery of the Preconscious Mind |publisher=[[University Press of America]] |year=2004 |isbn=0-7618-2765-X |pages=262–263 |access-date=December 11, 2018}}</ref><ref>{{Cite journal |last=SETTERSTEN |first=RICHARD |date=2015 |title=Becoming adult: Meanings of markers to adulthood |url=https://health.oregonstate.edu/sites/health.oregonstate.edu/files/faculty-staff/profilepubs/settersten_et_al-becoming_adult-emerging_trends.pdf |journal=Emerging Trends in the Social and Behavioral Sciences: An Interdisciplinary, Searchable, and Linkable Resource |pages=1–16 |via=umnikizdes}}</ref> In the past, a person usually moved from the status of child directly to the status of adult, often with this shift being marked by some type of coming-of-age test or ceremony.<ref>{{Cite news |last=Marantz Henig |first=Robin |author-link=Robin Marantz Henig |date=2010-08-18 |title=What Is It About 20-Somethings? |page=10 |work=The New York Times |url=https://www.nytimes.com/2010/08/22/magazine/22Adulthood-t.html |access-date=2010-09-24 |quote=The Discovery of adolescence is generally dated to 1904, with the publication of the massive study "Adolescence," by G. Stanley Hall, a prominent [[psychologist]] and first president of the American Psychological Association. |archive-date=2011-05-11 |archive-url=https://web.archive.org/web/20110511204449/http://www.nytimes.com/2010/08/22/magazine/22Adulthood-t.html |url-status=live }}</ref> During the [[Industrial Revolution]], children went to work as soon as they could in order to help provide for their family. There was not a huge emphasis on school or [[education]] in general. Many children could get a job and were not required to have experience as adults are nowadays.  In recent years, studies of adulthood have identified characteristic traits that go far beyond mere physical maturity.<ref>{{Cite journal |date=January 1983 |title=Has Fecundability been Declining in Recent Years in Developed Countries? |journal=Journal of Biosocial Science |volume=15 |issue=1 |doi=10.1017/s0021932000006349 |issn=0021-9320}}</ref> These markers for a full, mentally developed, adult include traits of personal responsibilities in multiple aspects of life.

Although few or no established dictionaries provide a definition for the two-word term ''biological adult'', the first definition of ''adult'' in multiple dictionaries includes "the stage of the life cycle of an animal after reproductive capacity has been attained".<ref>{{Cite book |title=International dictionary of medicine and biology |date=1986 |publisher=Wiley |isbn=0-471-01849-X |editor-last=Becker |oclc=801872498 |editor-last2=Landau |editor-first2=Sidney I.}}</ref><ref>{{Cite book |title=Churchill's illustrated medical dictionary |date=1989 |publisher=Churchill Livingstone |isbn=0-443-08691-5 |location=New York |oclc=19322374}}</ref> Thus, the base definition of the word ''adult'' is the period beginning at physical sexual maturity, which occurs sometime after the onset of puberty. Although this is the primary definition of the base word "adult", the term is also frequently used to refer to social adults. The two-word term ''biological adult'' stresses or clarifies that the original definition, based on physical maturity (i.e. having reached reproductive competency), is being used.<ref>{{Cite journal |last1=Gluckman |first1=Peter D. |last2=Hanson |first2=Mark A. |date=January 2006 |title=Evolution, development and timing of puberty |journal=Trends in Endocrinology & Metabolism |volume=17 |issue=1 |pages=7–12 |doi=10.1016/j.tem.2005.11.006 |pmid=16311040 |s2cid=26141301}}</ref>

The time of [[puberty]] varies from child to child, but usually begins between 10 and 12 years old. Girls typically begin the process of puberty at age 10 or 11, and boys at age 11 or 12.<ref name="Kail">{{Cite book |last1=Kail |first1=RV |url=https://books.google.com/books?id=E-n5E7oyCgoC&pg=PA296 |title=Human Development: A Lifespan View |last2=Cavanaugh JC |publisher=[[Cengage Learning]] |year=2010 |isbn=978-0-495-60037-4 |edition=5th |page=296 |access-date=2018-03-20 |archive-date=2023-01-10 |archive-url=https://web.archive.org/web/20230110011825/https://books.google.com/books?id=E-n5E7oyCgoC&pg=PA296 |url-status=live }}</ref><ref name="Schuiling">{{Cite book |last1=Schuiling |first1=Kerri Durnell |url=https://books.google.com/books?id=QTDFDAAAQBAJ&pg=PA22 |title=Women's Gynecologic Health |last2=Likis |first2=Frances E. |publisher=[[Jones & Bartlett Learning]] |year=2016 |isbn=978-1-284-12501-6 |page=22 |quote=The changes that occur during puberty usually happen in an ordered sequence, beginning with thelarche (breast development) at around age 10 or 11, followed by adrenarche (growth of pubic hair due to androgen stimulation), peak height velocity, and finally menarche (the onset of menses), which usually occurs around age 12 or 13. |access-date=March 20, 2018 |archive-date=January 10, 2023 |archive-url=https://web.archive.org/web/20230110011825/https://books.google.com/books?id=QTDFDAAAQBAJ&pg=PA22 |url-status=live }}</ref><ref name="Phillips">{{Cite book |last=Phillips |first=D. C. |url=https://books.google.com/books?id=84StBAAAQBAJ&pg=PA18 |title=Encyclopedia of Educational Theory and Philosophy |publisher=[[SAGE Publications]] |year=2014 |isbn=978-1-4833-6475-9 |pages=18–19 |quote=On average, the onset of puberty is about 18 months earlier for girls (usually starting around the age of 10 or 11 and lasting until they are 15 to 17) than for boys (who usually begin puberty at about the age of 11 to 12 and complete it by the age of 16 to 17, on average). |access-date=March 20, 2018 |archive-date=January 10, 2023 |archive-url=https://web.archive.org/web/20230110011826/https://books.google.com/books?id=84StBAAAQBAJ&pg=PA18 |url-status=live }}</ref> Girls generally complete puberty by 15–17, and boys by age 16 or 17.<ref name="Phillips" /><ref name="Solomon">{{Cite book |last1=Solomon |first1=Jean W. |url=https://books.google.com/books?id=E87sAwAAQBAJ&pg=PA103 |title=Pediatric Skills for Occupational Therapy Assistants – E-Book |last2=O'Brien |first2=Jane Clifford |publisher=[[Elsevier Health Sciences]] |year=2014 |isbn=978-0-323-29163-7 |page=103 |access-date=March 20, 2018}}</ref> Nutrition, genetics and environment also usually play a part in the onset of puberty.<ref name="xia">{{Cite journal |last1=Ge |first1=Xiaojia |last2=Natsuaki |first2=Misaki N. |last3=Neiderhiser |first3=Jenae M. |author-link3=Jenae Neiderhiser |last4=Reiss |first4=David |year=2007 |title=Genetic and Environmental Influences on Pubertal Timing: Results From Two National Sibling Studies |journal=Journal of Research on Adolescence |volume=17 |issue=4 |pages=767–788 |doi=10.1111/j.1532-7795.2007.00546.x}}</ref> Girls will go through a growth spurt and gain weight in several areas of their body. Boys will go through similar spurts in growth, though it is usually not in a similar style or time frame. This is due to the natural processes of puberty, but genetics also plays a part in how much weight they gain or how much taller they get.<ref>{{Cite web |date=2018-04-26 |title=Stages of puberty: what happens to boys and girls |url=https://www.nhs.uk/live-well/sexual-health/stages-of-puberty-what-happens-to-boys-and-girls/  |archive-url=https://web.archive.org/web/20201204165948/https://www.nhs.uk/live-well/sexual-health/stages-of-puberty-what-happens-to-boys-and-girls/ |archive-date=2020-12-04 |access-date=2020-12-13 |website=nhs.uk |language=en}}</ref>

One recent area of debate within the science of [[Development of the nervous system|brain development]] is the most likely chronological age for full [[Maturity (psychological)|mental maturity]], or indeed, if such an age even exists. Common claims repeated in the media since 2005 (based upon interpretations of imaging data) have commonly suggested an "end-point" of 25, referring to the [[prefrontal cortex]] as one area that is not yet fully mature at the age of 18. However, this is based on an interpretation of a brain imaging study by Jay Giedd, dating back to 2004 or 2005, where the only participants were aged up to 21 years, and Giedd assumed this maturing process would be done by the age of 25 years, whereas more recent studies show prefrontal cortex maturation continuing well past the age of 30 years, marking this interpretation as incorrect and outdated.<ref>{{Cite news |last=Henig |first=Robin Marantz |date=18 August 2010 |title=What is It About 20-Somethings? |work=The New York Times |url=https://www.nytimes.com/2010/08/22/magazine/22Adulthood-t.html |access-date=23 February 2017 |archive-date=26 February 2017 |archive-url=https://web.archive.org/web/20170226112204/http://www.nytimes.com/2010/08/22/magazine/22Adulthood-t.html |url-status=live }}</ref><ref>{{Cite journal |last1=Petanjek |first1=Zdravko |last2=Judaš |first2=Miloš |last3=Šimić |first3=Goran |last4=Rašin |first4=Mladen Roko |last5=Uylings |first5=Harry B. M. |last6=Rakic |first6=Pasko |last7=Kostović |first7=Ivica |year=2011 |title=Extraordinary neoteny of synaptic spines in the human prefrontal cortex |journal=Proceedings of the National Academy of Sciences |volume=108 |issue=32 |pages=13281–13286 |bibcode=2011PNAS..10813281P |doi=10.1073/pnas.1105108108 |pmc=3156171 |pmid=21788513 |doi-access=free}}</ref><ref>{{Cite news |date=19 March 2019 |title=People don't become 'adults' until their 30s, say scientists |work=BBC News |url=https://www.bbc.com/news/newsbeat-47622059 |access-date=14 June 2022 |archive-date=14 June 2022 |archive-url=https://web.archive.org/web/20220614054155/https://www.bbc.com/news/newsbeat-47622059 |url-status=live }}</ref><ref>{{Cite journal |last=Romer |first=Daniel |year=2010 |title=Adolescent risk taking, impulsivity, and brain development: implications for prevention |journal=Developmental Psychobiology |volume=52 |issue=3 |pages=263–276 |doi=10.1002/dev.20442 |pmc=3445337 |pmid=20175097}}</ref><ref>{{Cite journal |last1=Casey |first1=BJ |author-link=BJ Casey |last2=Caudle |first2=Kristina |year=2013 |title=The Teenage Brain: Self Control |journal=Current Directions in Psychological Science |volume=22 |issue=2 |pages=82–87 |doi=10.1177/0963721413480170 |pmc=4182916 |pmid=25284961}}</ref><ref>{{Cite web |last=Epstein |first=Robert |date=2007-06-01 |title=The Myth of the Teen Brain |url=https://www.scientificamerican.com/article/the-myth-of-the-teen-brain-2007-06/ |access-date=2021-12-07 |website=Scientific American |language=en |archive-date=2021-12-13 |archive-url=https://web.archive.org/web/20211213152824/https://www.scientificamerican.com/article/the-myth-of-the-teen-brain-2007-06/ |url-status=live }}</ref><ref>{{Cite book |last=Moshman |first=David |url=https://www.taylorfrancis.com/books/mono/10.4324/9780203835111/adolescent-rationality-development-david-moshman |title=Adolescent Rationality and Development |publisher=Psychology Press |year=2011 |isbn=978-0-203-83511-1 |doi=10.4324/9780203835111 |access-date=2021-12-07 |archive-date=2021-12-07 |archive-url=https://web.archive.org/web/20211207055923/https://www.taylorfrancis.com/books/mono/10.4324/9780203835111/adolescent-rationality-development-david-moshman |url-status=live }}</ref>