Editing Aggression (section)

====General====
Gender plays an important role in human aggression. There are multiple theories that seek to explain findings that males and females of the same species can have differing aggressive behaviors. One review concluded that male aggression tended to produce pain or physical injury whereas female aggression tended towards psychological or social harm.<ref name=pmid3797558>{{cite journal |doi=10.1037/0033-2909.100.3.309 |pmid=3797558 |title=Gender and aggressive behavior: A meta-analytic review of the social psychological literature |journal=Psychological Bulletin |volume=100 |issue=3 |pages=309–30 |year=1986 |last1=Eagly |first1=Alice H. |last2=Steffen |first2=Valerie J. }}</ref>

In general, [[sexual dimorphism]] can be attributed to greater [[intraspecific competition]] in one sex, either between rivals for access to mates and/or to be [[mate choice|chosen by mates]]. This may stem from the other gender being constrained by providing greater [[parental investment]], in terms of factors such as [[gamete]] production, [[gestation]], [[lactation]], or upbringing of young. Although there is much variation in species, generally the more physically aggressive sex is the male, particularly in mammals. In species where parental care by both sexes is required, there tends to be less of a difference. When the female can leave the male to care for the offspring, then females may be the larger and more physically aggressive. Competitiveness despite parental investment has also been observed in some species.<ref>{{cite journal |doi=10.1038/nature05386 |pmid=17183322 |title=Intrasexual competition and sexual selection in cooperative mammals |journal=Nature |volume=444 |issue=7122 |pages=1065–8 |year=2006 |last1=Clutton-Brock |first1=T. H. |last2=Hodge |first2=S. J. |last3=Spong |first3=G. |last4=Russell |first4=A. F. |last5=Jordan |first5=N. R. |last6=Bennett |first6=N. C. |last7=Sharpe |first7=L. L. |last8=Manser |first8=M. B. |bibcode=2006Natur.444.1065C |s2cid=4397323 }}</ref> A related factor is the rate at which males and females are able to mate again after producing offspring, and the basic principles of [[sexual selection]] are also influenced by ecological factors affecting the ways or extent to which one sex can compete for the other. The role of such factors in human evolution is controversial.

The pattern of male and female aggression is argued to be consistent with evolved sexually-selected behavioral differences, while alternative or complementary views emphasize conventional [[gender role|social roles]] stemming from physical evolved differences.<ref>{{cite journal |doi=10.1017/S0140525X09990951 |pmid=19691899 |title=Does sexual selection explain human sex differences in aggression? |journal=Behavioral and Brain Sciences |volume=32 |issue=3–4 |pages=249–66; discussion 266–311 |year=2009 |last1=Archer |first1=John |url=http://clok.uclan.ac.uk/1155/1/archer_J_does_sexual_selection_explain_2009.pdf }}</ref> Aggression in women may have evolved to be, on average, less physically dangerous and more covert or [[Indirect aggression|indirect]].<ref>{{cite journal |doi=10.1017/s0140525x99001818 |title=Staying alive: Evolution, culture, and women's intrasexual aggression |journal=Behavioral and Brain Sciences |volume=22 |issue=2 |year=1999 |last1=Campbell |first1=Anne |s2cid=1081104 |pmid=11301523 |pages=203–14; discussion 214–52}}</ref><ref>[https://books.google.com/books?id=esDW3xTKoLIC The Handbook of Evolutionary Psychology], edited by David M. Buss, John Wiley & Sons, Inc., 2005. Chapter 21 by Anne Campbell.{{page needed|date=February 2017}}</ref> However, there are critiques for using animal behavior to explain human behavior, especially in the application of evolutionary explanations to contemporary human behavior, including differences between the genders.<ref>Zuk, M. "[https://books.google.com/books/about/Sexual_selections.html?id=-Sjsmhm82wUC Sexual Selections: What We Can and Can't Learn about Sex from Animals.]" University of California Press, 2002{{page needed|date=February 2017}}</ref>

According to the 2015 ''[[International Encyclopedia of the Social & Behavioral Sciences]]'', sex differences in aggression is one of the most robust and oldest findings in psychology.<ref name = "274956064 Gender diff">{{cite book |doi=10.1016/B978-0-08-097086-8.25100-3 |chapter=Gender Differences in Personality and Social Behavior |title=International Encyclopedia of the Social & Behavioral Sciences |pages=750–6 |year=2015 |last1=Del Giudice |first1=Marco |hdl=2318/1852940 |isbn=978-0-08-097087-5 }}</ref> Past meta-analyses in the encyclopedia found males regardless of age engaged in more physical and verbal aggression while small effect for females engaging in more indirect aggression such as rumor spreading or gossiping.<ref name= "274956064 Gender diff"/> It also found males tend to engage in more unprovoked aggression at higher frequency than females.<ref name= "274956064 Gender diff"/> This analysis also conforms with the ''Oxford Handbook of Evolutionary Psychology'' which reviewed past analysis which found men to use more verbal and physical aggression with the difference being greater in the physical type.<ref>{{cite book |doi=10.1093/oxfordhb/9780198568308.013.0025 |year=2012 |last1=Campbell |first1=Anne |chapter=Sex differences in aggression |chapter-url={{Google books|8K7Hc09xcQAC|page=365|plainurl=yes}} |pages=365–82 |editor1-first=Louise |editor1-last=Barrett |editor2-first=Robin |editor2-last=Dunbar |title=Oxford Handbook of Evolutionary Psychology |isbn=978-0-19-856830-8 }}</ref>

There are more recent findings that show that differences in male and female aggression appear at about two years of age, though the differences in aggression are more consistent in middle-aged children and adolescence. Tremblay, Japel and Pérusse (1999) asserted that physically aggressive behaviors such as kicking, biting and hitting are age-typical expressions of innate and spontaneous reactions to biological drives such as anger, hunger, and affiliation.<ref>{{cite journal |doi=10.1002/bsl.2035 |pmid=22996132 |title=Gender Differences in Physical Aggression and Associated Developmental Correlates in a Sample of Canadian Preschoolers |journal=Behavioral Sciences & the Law |volume=30 |issue=5 |pages=643–71 |year=2012 |last1=Lussier |first1=Patrick |last2=Corrado |first2=Raymond |last3=Tzoumakis |first3=Stacy }}</ref> Girls' [[relational aggression]], meaning non-physical or indirect, tends to increase after age two while physical aggression decreases. There was no significant difference in aggression between males and females before two years of age.<ref name="Landsford 2012 298–308">{{cite journal |doi=10.1002/ab.21433 |pmid=23935227 |pmc=3736589 |title=Boys' and Girls' Relational and Physical Aggression in Nine Countries |journal=Aggressive Behavior |volume=38 |issue=4 |pages=298–308 |year=2012 |last1=Lansford |first1=Jennifer E. |last2=Skinner |first2=Ann T. |last3=Sorbring |first3=Emma |last4=Giunta |first4=Laura Di |last5=Deater-Deckard |first5=Kirby |last6=Dodge |first6=Kenneth A. |last7=Malone |first7=Patrick S. |last8=Oburu |first8=Paul |last9=Pastorelli |first9=Concetta |last10=Tapanya |first10=Sombat |last11=Uribe Tirado |first11=Liliana Maria |last12=Zelli |first12=Arnaldo |last13=Al-Hassan |first13=Suha M. |last14=Peña Alampay |first14=Liane |last15=Bacchini |first15=Dario |last16=Bombi |first16=Anna Silvia |last17=Bornstein |first17=Marc H. |last18=Chang |first18=Lei }}</ref> A possible explanation for this could be that girls develop language skills more quickly than boys, and therefore have better ways of verbalizing their wants and needs. They are more likely to use communication when trying to retrieve a toy with the words "Ask nicely" or "Say please."<ref name="Hay 2011 158–75">{{cite journal |doi=10.1111/j.2044-835x.2011.02028.x |pmid=21592146 |title=The emergence of gender differences in physical aggression in the context of conflict between young peers |journal=British Journal of Developmental Psychology |volume=29 |issue=2 |pages=158–75 |year=2011 |last1=Hay |first1=Dale F. |last2=Nash |first2=Alison |last3=Caplan |first3=Marlene |last4=Swartzentruber |first4=Jan |last5=Ishikawa |first5=Fumiko |last6=Vespo |first6=Jo Ellen |s2cid=206006344 }}</ref>

According to the journal of ''Aggressive Behaviour'', an analysis across 9 countries found boys reported more in the use of physical aggression.<ref name="Landsford 2012 298–308"/> At the same time no consistent sex differences emerged within relational aggression.<ref name="Landsford 2012 298–308" /> It has been found that girls are more likely than boys to use reactive aggression and then retract, but boys are more likely to increase rather than to retract their aggression after their first reaction. Studies show girls' aggressive tactics included [[gossip]], [[Social rejection|ostracism]], breaking confidences, and criticism of a victim's clothing, appearance, or personality, whereas boys engage in aggression that involves a direct physical and/or verbal assault.<ref>{{cite journal |doi=10.1016/j.evolhumbehav.2005.11.001 |title=Sex differences in indirect aggression |journal=Evolution and Human Behavior |volume=27 |issue=3 |pages=231–45 |year=2006 |last1=Hess |first1=Nicole H. |last2=Hagen |first2=Edward H. }}</ref> This could be due to the fact that girls' frontal lobes develop earlier than boys, allowing them to self-restrain.<ref name="Hay 2011 158–75"/>

One factor that shows insignificant differences between male and female aggression is in sports. In sports, the rate of aggression in both contact and non-contact sports is relatively equal. Since the establishment of Title IX, female sports have increased in competitiveness and importance, which could contribute to the evening of aggression and the "need to win" attitude between both genders. Among sex differences found in adult sports were that females have a higher scale of indirect hostility while men have a higher scale of assault.<ref>{{cite journal |last=Keeler |first=Linda A |title=The differences in sport aggression, life aggression, and life assertion among adult male and female collision, contact, and non-contact sport athletes |journal=Journal of Sport Behavior |year=2007 |volume=30 |issue=1 |pages=57–76 |url=https://www.proquest.com/openview/19a147ae672eead5e95f7141e6116794/1 }}</ref> Another difference found is that men have up to 20 times higher levels of [[testosterone]] than women.