Human

== Society ==
{{Main|Society}}
[[File:Indian family in Brazil posed in front of hut.jpg|thumb|upright|Humans often live in family-based social structures]]
Society is the system of organizations and institutions arising from interaction between humans. Humans are highly social and tend to live in large complex social groups. They can be divided into different groups according to their income, wealth, [[power (social and political)|power]], [[reputation]] and other factors. The structure of [[social stratification]] and the degree of [[social mobility]] differs, especially between modern and traditional societies.<ref>{{cite web |title=Social Stratification |url=https://web.unitn.it/files/download/8481/srs_schizzerotto_social_stratification_2_as.pdf |url-status=dead |archive-url=https://web.archive.org/web/20180320150018/https://web.unitn.it/files/download/8481/srs_schizzerotto_social_stratification_2_as.pdf |archive-date=20 March 2018 |access-date=3 July 2017 |publisher=[[University of Trento]] |vauthors=Schizzerotto A}}</ref> Human groups range from the size of [[Family|families]] to nations. The first form of human social organization is thought to have resembled [[hunter-gatherer]] [[Band society|band societies]].<ref>{{cite book| vauthors = Fukuyama F |title=The origins of political order : from prehuman times to the French Revolution|date=2012|publisher=Farrar, Straus and Giroux|isbn=978-0-374-53322-9|page=53|oclc=1082411117}}</ref>

=== Gender ===
{{Main|Gender|}}

Human societies typically exhibit [[Gender identity|gender identities]] and [[gender role]]s that distinguish between [[Masculinity|masculine]] and [[Femininity|feminine]] characteristics and prescribe the range of acceptable behaviours and attitudes for their members based on their [[sex]].<ref>{{Cite book |chapter=Social Role Theory of Sex Differences and Similarities : A Current Appraisal |date=2000 |chapter-url=https://www.taylorfrancis.com/chapters/edit/10.4324/9781410605245-12/social-role-theory-sex-differences-similarities-current-appraisal |title=The Developmental Social Psychology of Gender |pages=137–188 |publisher=Psychology Press |doi=10.4324/9781410605245-12 |isbn=978-1-4106-0524-5 |access-date=10 June 2022 |archive-date=30 April 2021 |archive-url=https://web.archive.org/web/20210430212712/https://www.taylorfrancis.com/chapters/edit/10.4324/9781410605245-12/social-role-theory-sex-differences-similarities-current-appraisal |url-status=live }}</ref><ref>{{Cite encyclopedia |year=2003 |title=Gender Roles and Society |encyclopedia=Human Ecology: An Encyclopedia of Children, Families, Communities, and Environments |publisher=ABC-CLIO |location=Santa barbara, CA |url=https://digitalcommons.library.umaine.edu/soc_facpub/1/ |last=Blackstone |first=Amy |series=Sociology School Faculty Scholarship |page=335 |editor-last=Miller |editor-first=Julia R. |editor2-last=Lerner |editor2-first=Richard M. |editor3-last=Schiamberg |editor3-first=Lawrence B. |access-date=30 July 2022 |archive-date=16 May 2022 |archive-url=https://web.archive.org/web/20220516131905/https://digitalcommons.library.umaine.edu/soc_facpub/1/ |url-status=live }}</ref> The most common categorisation is a [[gender binary]] of [[men]] and [[women]].<ref name="Nadal-re-binary">{{cite book|last=Nadal|first=Kevin L.|title=The SAGE Encyclopedia of Psychology and Gender|year=2017|isbn=978-1483384276|page=401|publisher=SAGE Publications |quote=Most cultures currently construct their societies based on the understanding of gender binary{{snd}}the two gender categorizations (male and female). Such societies divide their population based on biological sex assigned to individuals at birth to begin the process of gender socialization.}}</ref> Some societies recognise a [[third gender]],<ref>{{Cite book |last=Herdt |first=Gilbert |url={{GBurl|id=8nf8DwAAQBAJ}} |title=Third Sex, Third Gender: Beyond Sexual Dimorphism in Culture and History |publisher=Princeton University Press |year=2020 |isbn=978-1-942130-52-9 |location=Princeton, NJ |pages=21–83 |language=en |chapter=Third Sexes and Third Genders |access-date=30 July 2022 }}</ref> or less commonly a fourth or fifth.<ref>{{cite book|last=Trumbach|first=Randolph|year=1994|chapter=London's Sapphists: From Three Sexes to Four Genders in the Making of Modern Culture|title=Third Sex, Third Gender: Beyond Sexual Dimorphism in Culture and History|editor-last=Herdt|editor-first=Gilbert|pages=111–136|location=New York|publisher=Zone (MIT)|isbn=978-0-942299-82-3}}</ref><ref name="Graham">{{cite web|last=Graham|first=Sharyn|url=http://www.insideindonesia.org/weekly-articles/sulawesis-fifth-gender|title=Sulawesi's fifth gender|archive-url=https://web.archive.org/web/20141126200244/http://www.insideindonesia.org/weekly-articles/sulawesis-fifth-gender|archive-date=26 November 2014|website=[[Inside Indonesia]]|date=April–June 2001}}</ref> In some other societies, [[Non-binary gender|non-binary]] is used as an umbrella term for a range of gender identities that are not solely male or female.<ref name="richardsetal">{{Cite journal |last1=Richards |first1=Christina |last2=Bouman |first2=Walter Pierre |last3=Seal |first3=Leighton |last4=Barker |first4=Meg John |author4-link=Meg-John Barker |last5=Nieder |first5=Timo O. |last6=T'Sjoen |first6=Guy |date=2016 |title=Non-binary or genderqueer genders |url=https://biblio.ugent.be/publication/7279758 |url-status=live |journal=International Review of Psychiatry |volume=28 |issue=1 |pages=95–102 |doi=10.3109/09540261.2015.1106446 |pmid=26753630 |archive-url=https://web.archive.org/web/20190626224658/https://biblio.ugent.be/publication/7279758 |archive-date=26 June 2019 |access-date=9 June 2019 |hdl-access=free |s2cid=29985722 |hdl=1854/LU-7279758}}</ref>

Gender roles are often associated with a division of [[social norm|norms]], [[practice (social theory)|practices]], [[clothing|dress]], [[social behavior|behavior]], [[rights]], [[duty|duties]], [[Privilege (social inequality)|privileges]], [[social status|status]], and [[power (social and political)|power]], with men enjoying more rights and privileges than women in most societies, both today and in the past.<ref>{{Cite web |last1=Ananthaswamy |first1=Anil|last2=Douglas|first2=Kate |title=The origins of sexism: How men came to rule 12,000 years ago |url=https://www.newscientist.com/article/mg23831740-400-the-origins-of-sexism-how-men-came-to-rule-12000-years-ago/ |access-date=7 March 2023 |website=New Scientist |language=en-US}}</ref> As a [[Social constructionism|social construct]],<ref name="www.who.int">{{Cite web |title=What do we mean by "sex" and "gender"? |url=https://apps.who.int/gender/whatisgender/en/ |url-status=dead |archive-url=https://web.archive.org/web/20170130022356/https://apps.who.int/gender/whatisgender/en/ |archive-date=30 January 2017 |access-date=26 November 2015 |publisher=[[World Health Organization]]}}</ref> gender roles are not fixed and vary historically within a society. Challenges to predominant gender norms have recurred in many societies.<ref>{{cite book |url={{GBurl|id=lc-YBRQkldAC|p=143}} |title=Essential Concepts for Healthy Living |vauthors=Alters S, Schiff W |publisher=[[Jones & Bartlett Publishers]] |year=2009 |isbn=978-0-7637-5641-3 |page=143 |access-date=3 January 2018}}</ref><ref>{{cite journal |author-link1=Nicole Fortin |vauthors=Fortin N |year=2005 |title=Gender Role Attitudes and the Labour Market Outcomes of Women Across OECD Countries |journal=Oxford Review of Economic Policy |volume=21 |issue=3 |pages=416–438 |doi=10.1093/oxrep/gri024}}</ref> Little is known about gender roles in the earliest human societies. [[Early modern human]]s probably had a range of gender roles similar to that of modern cultures from at least the [[Upper Paleolithic]], while the [[Neanderthal]]s were less sexually dimorphic and there is evidence that the behavioural difference between males and females was minimal.<ref>{{Cite book |last=Dobres |first=Marcia-Anne |author-link=Marcia-Anne Dobres |chapter=Gender in the Earliest Human Societies |date=27 November 2020 |chapter-url=https://onlinelibrary.wiley.com/doi/10.1002/9781119535812.ch11 |title=A Companion to Global Gender History |pages=183–204 |editor-last=Meade |editor-first=Teresa A. |edition=1 |publisher=Wiley |language=en |doi=10.1002/9781119535812.ch11 |isbn=978-1-119-53580-5 |access-date=10 June 2022 |editor2-last=Wiesner-Hanks |editor2-first=Merry E. |editor2-link=Merry Wiesner-Hanks |s2cid=229399965 |archive-date=10 June 2022 |archive-url=https://web.archive.org/web/20220610113514/https://onlinelibrary.wiley.com/doi/10.1002/9781119535812.ch11 |url-status=live }}</ref>

=== Kinship ===
{{Main|Kinship|}}
All human societies organize, recognize and classify types of social relationships based on relations between parents, children and other descendants ([[consanguinity]]), and relations through [[marriage]] ([[Affinity (law)|affinity]]). There is also a third type applied to [[godparent]]s or [[Adoption|adoptive children]] ([[Fictive kinship|fictive]]). These culturally defined relationships are referred to as kinship. In many societies, it is one of the most important social organizing principles and plays a role in transmitting status and [[inheritance]].<ref>{{cite web|title=The Nature of Kinship: Overview|url=https://www2.palomar.edu/anthro/kinship/kinship_1.htm|access-date=24 October 2020|website=www2.palomar.edu|archive-date=3 December 2020|archive-url=https://web.archive.org/web/20201203230431/https://www2.palomar.edu/anthro/kinship/kinship_1.htm|url-status=live}}</ref>&nbsp;All societies have rules of [[incest taboo]], according to which marriage between certain kinds of kin relations is prohibited, and some also have rules of preferential marriage with certain kin relations.<ref>{{cite journal | vauthors = Itao K, Kaneko K | title = Evolution of kinship structures driven by marriage tie and competition | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 117 | issue = 5 | pages = 2378–2384 | date = February 2020 | pmid = 31964846 | pmc = 7007516 | doi = 10.1073/pnas.1917716117 | bibcode = 2020PNAS..117.2378I | doi-access = free }}</ref>

=== Ethnicity ===
{{Main|Ethnic group}}
Human ethnic groups are a social category that [[Identity (social science)|identifies]] together as a group based on shared attributes that distinguish them from other groups. These can be a common set of traditions, [[ancestry]], [[language]], [[history]], [[society]], [[culture]], [[nation]], [[religion]], or social treatment within their residing area.<ref>{{cite book|first=Kanchan |last=Chandra |author-link=Kanchan Chandra|url=https://worldcat.org/oclc/829678440|title=Constructivist theories of ethnic politics|date=2012|publisher=Oxford University Press|isbn=978-0-19-989315-7|pages=69–70|oclc=829678440|access-date=30 July 2022|archive-date=30 July 2022|archive-url=https://web.archive.org/web/20220730033538/https://www.worldcat.org/title/constructivist-theories-of-ethnic-politics/oclc/829678440|url-status=live}}</ref><ref>{{cite book| vauthors = People J, Bailey G |title=Humanity: An Introduction to Cultural Anthropology|publisher=Wadsworth Cengage learning|year=2010|edition=9th|page=389|quote=In essence, an ethnic group is a named social category of people based on perceptions of shared social experience or one's ancestors' experiences. Members of the ethnic group see themselves as sharing cultural traditions and history that distinguish them from other groups. Ethnic group identity has a strong psychological or emotional component that divides the people of the world into opposing categories of ‘us’ and ‘them.’ In contrast to social stratification, which divides and unifies people along a series of horizontal axes based on socioeconomic factors, ethnic identities divide and unify people along a series of vertical axes. Thus, ethnic groups, at least theoretically, cut across socioeconomic class differences, drawing members from all strata of the population.}}</ref> Ethnicity is separate from the concept of [[Race (human categorization)|race]], which is based on physical characteristics, although both are [[Social constructionism|socially constructed]].<ref>{{cite web|vauthors=Blackmore E|date=22 February 2019|title=Race and ethnicity: How are they different?|url=https://www.nationalgeographic.com/culture/topics/reference/race-ethnicity/|access-date=24 October 2020|website=Culture|language=en|archive-date=22 October 2020|archive-url=https://web.archive.org/web/20201022013516/https://www.nationalgeographic.com/culture/topics/reference/race-ethnicity/|url-status=dead}}</ref> Assigning ethnicity to a certain population is complicated, as even within common ethnic designations there can be a diverse range of subgroups, and the makeup of these ethnic groups can change over time at both the collective and individual level.<ref name="REGWG2005" /> Also, there is no generally accepted definition of what constitutes an ethnic group.<ref>{{cite journal|vauthors=Chandra K|title=What is Ethnic Identity and Does It Matter?|date=2006|journal=Annual Review of Political Science|language=en|volume=9|issue=1|pages=397–424|doi=10.1146/annurev.polisci.9.062404.170715|issn=1094-2939|doi-access=free}}</ref> Ethnic groupings can play a powerful role in the [[social identity]] and solidarity of ethnopolitical units. This has been closely tied to the rise of the [[nation state]] as the predominant form of political organization in the 19th and 20th centuries.<ref>{{cite book | vauthors = Smith AD | date = 1999 | title = Myths and Memories of the Nation. | publisher = Oxford University Press | pages = 4–7 }}</ref><ref>{{cite journal| vauthors = Banton M |year=2007|title=Max Weber on 'ethnic communities': a critique|journal=Nations and Nationalism|volume=13|issue=1|pages=19–35|doi=10.1111/j.1469-8129.2007.00271.x}}</ref><ref>{{cite book | vauthors = Delanty G, Kumar K |title=The SAGE Handbook of Nations and Nationalism |date=2006 |publisher=Sage |location=London |isbn=978-1-4129-0101-7 | page = 171 }}</ref>

=== Government and politics ===
{{Main|Government|Politics|||}}
[[File:United Nations Headquarters in New York City, view from Roosevelt Island.jpg|thumb|right|The [[Headquarters of the United Nations|United Nations headquarters]] in New York City, which houses one of the world's largest political organizations]]
As farming populations gathered in larger and denser communities, interactions between these different groups increased. This led to the development of governance within and between the communities.<ref>{{cite book| vauthors = Christian D |url=https://archive.org/details/mapsoftimeintrod00chri|title=Maps of Time|date=2004|publisher=University of California Press|isbn=978-0-520-24476-4|url-access=registration}}</ref> Humans have evolved the ability to change affiliation with various social groups relatively easily, including previously strong political alliances, if doing so is seen as providing personal advantages.<ref>{{cite web|vauthors=Cronk L, Leech BL|date=20 September 2017|title=How Did Humans Get So Good at Politics?|url=https://www.sapiens.org/evolution/human-evolution-politics/|access-date=24 October 2020|website=SAPIENS|language=en-US|archive-date=7 August 2020|archive-url=https://web.archive.org/web/20200807003627/https://www.sapiens.org/evolution/human-evolution-politics/|url-status=live}}</ref> This [[cognitive flexibility]] allows individual humans to change their political ideologies, with those with higher flexibility less likely to support authoritarian and nationalistic stances.<ref>{{cite journal | vauthors = Zmigrod L, Rentfrow PJ, Robbins TW | title = Cognitive underpinnings of nationalistic ideology in the context of Brexit | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 115 | issue = 19 | pages = E4532–E4540 | date = May 2018 | pmid = 29674447 | pmc = 5948950 | doi = 10.1073/pnas.1708960115 | bibcode = 2018PNAS..115E4532Z | s2cid = 4993139 | doi-access = free }}</ref>

Governments create [[law]]s and [[policies]] that affect the citizens that they govern. There have been [[List of forms of government|many forms of government]] throughout human history, each having various means of obtaining power and the ability to exert diverse controls on the population.<ref>{{cite web|date=14 February 2011|vauthors=Melina R|title=What Are the Different Types of Governments?|url=https://www.livescience.com/33027-what-are-the-different-types-of-governments.html|access-date=24 October 2020|website=livescience.com|language=en|archive-date=1 February 2021|archive-url=https://web.archive.org/web/20210201203345/https://www.livescience.com/33027-what-are-the-different-types-of-governments.html|url-status=live}}</ref> Approximately 47% of humans live in some form of a [[democracy]], 17% in a [[hybrid regime]], and 37% in an [[authoritarian regime]].<ref>{{cite web|work=[[The Economist Democracy Index]]|title=Democracy Index 2021: less than half the world lives in a democracy|date=February 10, 2022|publisher=[[Economist Intelligence Unit]]|url=https://www.eiu.com/n/democracy-index-2021-less-than-half-the-world-lives-in-a-democracy/}}</ref> Many countries belong to [[international organization|international organizations]] and [[alliances]]; the largest of these is the [[United Nations]], with [[Member states of the United Nations|193 member states]].<ref>{{cite web|author=Jeannie Evers|date=23 December 2012|title=international organization|url=https://education.nationalgeographic.org/resource/international-organization/|access-date=24 October 2020|website=National Geographic Society|language=en|archive-date=27 April 2017|archive-url=https://web.archive.org/web/20170427195211/http://www.nationalgeographic.org/encyclopedia/international-organization/|url-status=live}}</ref>

=== Trade and economics ===
{{Main|Trade|Economics}}
[[File:Silk route.jpg|thumb|upright=1.3|The [[Silk Road]] (red) and spice [[trade routes]] (blue)]]
Trade, the voluntary exchange of goods and services, is seen as a characteristic that differentiates humans from other animals and has been cited as a practice that gave ''Homo sapiens'' a major advantage over other hominids.<ref>{{cite journal| vauthors = Horan RD, Bulte E, Shogren JF |date=1 September 2005|title=How trade saved humanity from biological exclusion: an economic theory of Neanderthal extinction |journal=Journal of Economic Behavior & Organization|language=en|volume=58|issue=1|pages=1–29|doi=10.1016/j.jebo.2004.03.009|issn=0167-2681}}</ref> Evidence suggests early ''H. sapiens'' made use of long-distance trade routes to exchange goods and ideas, leading to [[cultural explosion]]s and providing additional food sources when hunting was sparse, while such trade networks did not exist for the now extinct Neanderthals.<ref>{{cite web|vauthors=Gibbons J|date=11 August 2015|title=Why did Neanderthals go extinct?|url=https://insider.si.edu/2015/08/why-did-neanderthals-go-extinct/|access-date=11 October 2020|website=Smithsonian Insider|language=en-US|archive-date=12 November 2020|archive-url=https://web.archive.org/web/20201112021755/https://insider.si.edu/2015/08/why-did-neanderthals-go-extinct/|url-status=live}}</ref><ref>{{cite web|author=University of Wyoming|date=24 March 2005|title=Did Use of Free Trade Cause Neanderthal Extinction?|url=https://www.newswise.com/articles/did-use-of-free-trade-cause-neanderthal-extinction|access-date=11 October 2020|website=www.newswise.com|language=en|archive-date=1 February 2021|archive-url=https://web.archive.org/web/20210201191705/https://www.newswise.com/articles/did-use-of-free-trade-cause-neanderthal-extinction|url-status=live}}</ref> Early trade likely involved materials for creating tools like [[obsidian]].<ref>{{cite web|vauthors=Polianskaya A|date=15 March 2018|title=Humans may have been trading with each for as long as 300,000 years|url=https://inews.co.uk/news/science/early-humans-trading-300000-years-135655|access-date=11 October 2020|website=inews.co.uk|language=en|archive-date=23 January 2021|archive-url=https://web.archive.org/web/20210123015959/https://inews.co.uk/news/science/early-humans-trading-300000-years-135655|url-status=live}}</ref> The first truly international trade routes were around the [[spice trade]] through the Roman and medieval periods.<ref>{{cite news|vauthors=Henriques M|title=How spices changed the ancient world|url=https://www.bbc.com/future/bespoke/made-on-earth/the-flavours-that-shaped-the-world/|access-date=11 October 2020|website=www.bbc.com|language=en|archive-date=25 January 2021|archive-url=https://web.archive.org/web/20210125075428/https://www.bbc.com/future/bespoke/made-on-earth/the-flavours-that-shaped-the-world/|url-status=live}}</ref>

Early human [[Economy|economies]] were more likely to be based around [[Gift economy|gift giving]] instead of a [[barter]]ing system.<ref>{{cite web|vauthors=Strauss IE|date=26 February 2016|title=The Myth of the Barter Economy|url=https://www.theatlantic.com/business/archive/2016/02/barter-society-myth/471051/|access-date=11 October 2020|website=The Atlantic|language=en-US|archive-date=15 February 2021|archive-url=https://web.archive.org/web/20210215153209/https://www.theatlantic.com/business/archive/2016/02/barter-society-myth/471051/|url-status=live}}</ref> Early [[money]] consisted of [[Commodity money|commodities]]; the oldest being in the form of cattle and the most widely used being [[cowrie shells]].<ref name="www.pbs.org-1996">{{cite web|title=The History of Money|url=https://www.pbs.org/wgbh/nova/article/history-money/|access-date=11 October 2020|website=www.pbs.org|date=26 October 1996 |language=en-US|archive-date=29 November 2020|archive-url=https://web.archive.org/web/20201129121807/https://www.pbs.org/wgbh/nova/article/history-money/|url-status=live}}</ref> Money has since evolved into governmental issued [[coins]], [[Paper money|paper]] and [[electronic money]].<ref name="www.pbs.org-1996" /> Human study of economics is a [[social science]] that looks at how societies distribute scarce resources among different people.<ref>{{cite web|title=Why do we need economists and the study of economics?|url=https://www.frbsf.org/education/publications/doctor-econ/2000/july/economics-economists/|access-date=23 October 2020|website=Federal Reserve Bank of San Francisco|date=July 2000 |language=en|archive-date=12 November 2020|archive-url=https://web.archive.org/web/20201112023941/https://www.frbsf.org/education/publications/doctor-econ/2000/july/economics-economists/|url-status=live}}</ref> There are massive [[Economic inequality|inequalities]] in the division of [[wealth]] among humans; the eight richest humans are worth the same monetary value as the poorest half of all the human population.<ref>{{cite web|vauthors=Sheskin M|title=The inequality delusion: Why we've got the wealth gap all wrong|url=https://www.newscientist.com/article/mg23731710-300-the-inequality-delusion-why-weve-got-the-wealth-gap-all-wrong/|access-date=24 October 2020|website=New Scientist|language=en-US|archive-date=3 February 2021|archive-url=https://web.archive.org/web/20210203042931/https://www.newscientist.com/article/mg23731710-300-the-inequality-delusion-why-weve-got-the-wealth-gap-all-wrong/|url-status=live}}</ref>

=== Conflict ===
{{further information|War|Violence}}
[[File:Into the Jaws of Death 23-0455M edit.jpg|thumb|American troops [[Normandy landings|landing at Normandy]], WWII.]]
Humans commit violence on other humans at a rate comparable to other primates, but have an increased preference for killing adults, [[Infanticide (zoology)|infanticide]] being more common among other primates.<ref>{{cite web|vauthors=Yong E|date=28 September 2016|title=Humans: Unusually Murderous Mammals, Typically Murderous Primates|url=https://www.theatlantic.com/science/archive/2016/09/humans-are-unusually-violent-mammals-but-averagely-violent-primates/501935/|access-date=7 May 2021|website=The Atlantic|language=en|archive-date=7 May 2021|archive-url=https://web.archive.org/web/20210507121602/https://www.theatlantic.com/science/archive/2016/09/humans-are-unusually-violent-mammals-but-averagely-violent-primates/501935/|url-status=live}}</ref> Phylogenetic analysis predicts that 2% of early ''H. sapiens'' would be [[murder]]ed, rising to 12% during the medieval period, before dropping to below 2% in modern times.<ref>{{cite journal | vauthors = Gómez JM, Verdú M, González-Megías A, Méndez M | title = The phylogenetic roots of human lethal violence | journal = Nature | volume = 538 | issue = 7624 | pages = 233–237 | date = October 2016 | pmid = 27680701 | doi = 10.1038/nature19758 | bibcode = 2016Natur.538..233G | s2cid = 4454927 }}</ref> There is great variation in violence between human populations, with rates of homicide about 0.01% in societies that have [[List of national legal systems|legal systems]] and strong cultural attitudes against violence.<ref>{{cite journal | vauthors = Pagel M | title = Animal behaviour: Lethal violence deep in the human lineage | journal = Nature | volume = 538 | issue = 7624 | pages = 180–181 | date = October 2016 | pmid = 27680700 | doi = 10.1038/nature19474 | bibcode = 2016Natur.538..180P | s2cid = 4459560 | url = https://centaur.reading.ac.uk/67361/1/Pagel%20N%26V%20on%20Gomez%20et%20al.pdf | access-date = 30 July 2022 | archive-date = 20 May 2022 | archive-url = https://web.archive.org/web/20220520203015/https://centaur.reading.ac.uk/67361/1/Pagel%20N%26V%20on%20Gomez%20et%20al.pdf | url-status = live }}</ref>

The willingness of humans to kill other members of their species en masse through organized conflict (i.e., war) has long been the subject of debate. One school of thought holds that war evolved as a means to eliminate competitors, and has always been an innate human characteristic. Another suggests that war is a relatively recent phenomenon and has appeared due to changing social conditions.<ref name="Ferguson-2018">{{cite web|vauthors=Ferguson RB|date=1 September 2018|title=War Is Not Part of Human Nature|url=https://www.scientificamerican.com/article/war-is-not-part-of-human-nature/|website=Scientific American|access-date=30 July 2022|archive-date=30 January 2021|archive-url=https://web.archive.org/web/20210130124940/https://www.scientificamerican.com/article/war-is-not-part-of-human-nature/|url-status=live}}</ref> While not settled, current evidence indicates warlike predispositions only became common about 10,000 years ago, and in many places much more recently than that.<ref name="Ferguson-2018" /> War has had a high cost on human life; it is estimated that during the 20th century, between 167 million and 188 million people died as a result of war.<ref>{{cite magazine | vauthors = Ferguson N | title = The Next War of the World | magazine = Foreign Affairs | date = September–October 2006 | url = https://www.foreignaffairs.com/articles/middle-east/2006-09-01/next-war-world | access-date = 30 July 2022 | archive-date = 25 April 2022 | archive-url = https://web.archive.org/web/20220425051203/https://www.foreignaffairs.com/articles/middle-east/2006-09-01/next-war-world | url-status = live }}</ref> War casualty data is less reliable for pre-medieval times, especially global figures. But compared with any period over the past 600 years, the last ~80 years (post 1946), has seen a very significant drop in global military and civilian death rates due to armed conflict. <ref>{{Cite web|url=https://www.vox.com/2015/6/23/8832311/war-casualties-600-years|title=600 years of war and peace, in one amazing chart|first=Zack|last=Beauchamp|date=June 23, 2015|website=Vox}}</ref>