Editing Chimpanzee (section)

==Behaviour==
Recent studies have suggested that human observers influence chimpanzee behaviour. One suggestion is that [[Unmanned aerial vehicle|drone]]s, camera traps, and remote microphones should be used to record and monitor chimpanzees rather than direct human observation.<ref>{{cite journal |last1=Hobaiter |first1=C. |last2=Samuni |first2=L. |last3=Mullins |first3=C. |last4=Akankwasa |first4=W. J. |last5=Zuberbühler |first5=K. |year=2017 |title=Variation in hunting behaviour in neighbouring chimpanzee communities in the Budongo forest, Uganda |journal=PLOS ONE |volume=12 |issue=6 |page=e0178065 |doi=10.1371/journal.pone.0178065 |pmid=28636646 |pmc=5479531 |bibcode=2017PLoSO..1278065H |doi-access=free}}</ref>{{Failed verification | date = October 2024 | reason = The research mentions nothing about drone, cameras, or microphones.}}

===Group structure===
[[File:Chimpanzees in Uganda (5984913059).jpg|thumb|Group in Uganda]]
Chimpanzees live in communities that typically range from around 15 to more than 150 members but spend most of their time traveling in small, temporary groups consisting of a few individuals. These groups may consist of any combination of age and sexes. Both males and females sometimes travel alone.<ref name="behavior monographs">{{cite journal |last=Van Lawick-Goodall |first=J. |author-link=Jane Goodall |year=1968 |title=The behaviour of free-living chimpanzees in the Gombe Stream Reserve |journal=Animal Behaviour Monographs (Rutgers University) |volume=1 |issue=3 |page=167}}</ref> This [[fission–fusion society]] may include groups of four types: all-male, adult females and offspring, adults of both sexes, or one female and her offspring. These smaller groups emerge in a variety of types, for a variety of purposes. For example, an all-male troop may be organised to [[hunting|hunt]] for meat, while a group consisting of lactating females serves to act as a "nursery group" for the young.<ref name="Pepper"/>

At the core of social structures are males, which patrol the territory, protect group members, and search for food. Males remain in their natal communities, while females generally emigrate at adolescence. Males in a community are more likely to be related to one another than females are to each other. Among males, there is generally a dominance hierarchy, and males are dominant over females.<ref>{{cite journal |last1=Goldberg |first1=T. L. |last2=Wrangham |first2=R. W. |author2-link=Richard Wrangham |title=Genetic correlates of social behavior in wild chimpanzees: evidence from mitochondrial DNA |journal=Animal Behaviour |volume=54 |issue=3 |pages=559–70 |date=September 1997 |pmid=9299041 |doi=10.1006/anbe.1996.0450 |s2cid=18223362}}</ref> However, this unusual fission-fusion social structure, "in which portions of the parent group may on a regular basis separate from and then rejoin the rest,"{{sfn|Goodall|1986|p=147}} is highly variable in terms of which particular individual chimpanzees congregate at a given time. This is caused mainly by the large measure of individual autonomy that individuals have within their fission-fusion social groups.<ref name="Estes"/> As a result, individual chimpanzees often forage for food alone, or in smaller groups, as opposed to the much larger "parent" group, which encompasses all the chimpanzees which regularly come into contact with each other and congregate into parties in a particular area.<ref name="Pepper">{{cite journal |last1=Pepper |first1=J. W. |last2=Mitani |first2=J. C. |last3=Watts |first3=D. P. |year=1999 |title=General gregariousness and specific social preferences among wild chimpanzees |journal=International Journal of Primatology |volume=20 |issue=5 |pages=613–32 |doi=10.1023/A:1020760616641 |citeseerx=10.1.1.1000.4734|s2cid=25222840}}</ref>
[[File:013 Alpha male chimpanzee at Kibale forest National Park Photo by Giles Laurent.jpg|left|alt=Alpha male chimpanzee at Kibale National Park, Uganda|thumb|Alpha male chimpanzee at [[Kibale National Park]], Uganda.]]
Male chimpanzees exist in a linear [[dominance hierarchy]]. Top-ranking males tend to be aggressive even during dominance stability.<ref name="Muller2002">{{cite book |last=Muller |first=M. N. |date=2002 |chapter=Agonistic relations among Kanyawara chimpanzees |pages=112–124 |editor-last=Boesch |editor-first=C. |display-editors=etal |title=Behavioural Diversity in Chimpanzees and Bonobos |location=Cambridge |publisher=Cambridge University Press |isbn=0-521-00613-9}}</ref> This is probably due to the chimpanzee's fission-fusion society, with male chimpanzees leaving groups and returning after extended periods of time. With this, a dominant male is unsure if any "political maneuvering" has occurred in his absence and must re-establish his dominance. Thus, a large amount of aggression occurs within five to fifteen minutes after a reunion. During these encounters, displays of aggression are generally preferred over physical attacks.<ref name="Muller2002"/><ref name="Bygott1979">{{cite book |last=Bygott |first=J. D. |date=1979 |chapter=Agonistic behavior, dominance, and social structure in wild chimpanzees of the Gombe National Park |pages=73–121 |editor-last1=Hamburg |editor1-first=D. A. |editor-last2=McCown |editor-first2=E. R. |title=The Great Apes |location=Menlo Park |publisher=Benjamin-Cummings |isbn=978-0-8053-3669-6 |chapter-url=https://archive.org/details/greatapes0000unse_n7y7/page/73}}</ref>

Males maintain and improve their social ranks by forming coalitions, which have been characterised as "exploitative" and based on an individual's influence in agonistic interactions.<ref name="deWaal1987">{{cite book |last=de Waal |first=F. B. |author-link=Frans de Waal |date=1987 |chapter=Dynamic of social relationships |pages=421–429 |editor-last=Smuts |editor-first=B. B. |display-editors=etal |title=Primate Societies |location=Chicago |publisher=University of Chicago Press |isbn=978-0-226-76716-1}}</ref> Being in a coalition allows males to dominate a third individual when they could not by themselves, as politically apt chimpanzees can exert power over aggressive interactions regardless of their rank. Coalitions can also give an individual male the confidence to challenge a dominant or larger male. The more allies a male has, the better his chance of becoming dominant. However, most changes in hierarchical rank are caused by [[Dyad (sociology)|dyadic]] interactions.<ref name="Muller2002"/><ref name="Watts2001"/> Chimpanzee alliances can be very fickle, and one member may suddenly turn on another if it is to his advantage.<ref name="Nishida1986">{{cite book |last1=Nishida |first1=T. |last2=Hiraiwa-Hasegawa |first2=M. |date=1986 |chapter=Chimpanzees and bonobos: cooperative relationships among males |pages=165–177 |editor-last=Smuts |editor-first=B. B. |display-editors=etal |title=Primate Societies |location=Chicago and London |publisher=The University of Chicago Press |isbn=978-0-226-76716-1}}</ref>
[[File:Gombe Stream NP gegenseitiges Lausen.jpg|thumb|Mutual grooming, removing [[Louse|lice]]]]
Low-ranking males frequently switch sides in disputes between more dominant individuals. Low-ranking males benefit from an unstable hierarchy and often find increased sexual opportunities if a dispute or conflict occurs.<ref name="deWaal1987"/><ref name="Nishida1986"/> In addition, conflicts between dominant males cause them to focus on each other rather than the lower-ranking males. Social hierarchies among adult females tend to be weaker. Nevertheless, the status of an adult female may be important for her offspring.<ref name="Pusey1997"/> Females in [[Taï National Park|Taï]] have also been recorded to form alliances.<ref>{{cite book |author=Stumpf, R. |date=2007 |chapter=Chimpanzees and Bonobos: Diversity Within and Between Species |pages=321–344 |editor=Campbell C. J. |display-editors=etal |title=Primates in perspective |location=New York |publisher=Oxford University Press |isbn=978-0-19-539043-8}}</ref> While chimpanzee social structure is often referred to as [[patriarchal]], it is not entirely unheard of for females to forge coalitions against males.<ref>{{Cite journal |last=Newton-Fisher|first=N. E. |date=2006 |title=Female coalitions against male aggression in wild chimpanzees of the Budongo Forest |journal=International Journal of Primatology |volume=27 |issue=6 |pages=1589–1599 |doi=10.1007/s10764-006-9087-3 |s2cid=22066848 |issn=1573-8604}}</ref> There is also at least one recorded case of females securing a dominant position over males in their respective troop, albeit in a captive environment.<ref>{{Cite web |last=Wojci |first=A. |title=The rise and fall of a chimpanzee matriarchy |publisher=Przekrój Magazine |url=https://przekroj.pl/en/science/the-rise-and-fall-of-a-chimpanzee-matriarchy-agnieszka-wojci |access-date=18 August 2020 |website=[[Przekrój]] |date=20 October 2018 |language=en |archive-date=25 January 2021 |archive-url=https://web.archive.org/web/20210125213620/https://przekroj.pl/en/science/the-rise-and-fall-of-a-chimpanzee-matriarchy-agnieszka-wojci |url-status=live }}</ref> [[Social grooming]] appears to be important in the formation and maintenance of coalitions. It is more common among adult males than either between adult females or between males and females.<ref name="Watts2001">{{cite journal |author=Watts, D. P. |year=2001 |title=Reciprocity and interchange in the social relationships of wild male chimpanzees |journal=Behaviour |volume=139 |issue=2 |pages=343–370 |doi=10.1163/156853902760102708 |url=http://www2.unine.ch/repository/default/content/sites/ethol/files/shared/documents/watts_2002.pdf |archive-url=https://web.archive.org/web/20150421014820/http://www2.unine.ch/repository/default/content/sites/ethol/files/shared/documents/watts_2002.pdf |archive-date=2015-04-21 |url-status=live |citeseerx=10.1.1.516.3624}}</ref>
[[File:Adult male chimps in mahale.jpg|thumb|left |Males in Mahale National Park, Tanzania]]
Chimpanzees have been described as highly territorial and will frequently kill other chimpanzees,<ref>{{cite magazine |last=Walsh |first=B. |url=http://www.time.com/time/health/article/0,8599,1880229,00.html |archive-url=https://web.archive.org/web/20090219145829/http://www.time.com/time/health/article/0,8599,1880229,00.html |url-status=dead |archive-date=19 February 2009 |title=Why the Stamford chimp attacked |magazine=Time |date=18 February 2009 |access-date=6 June 2009}}</ref> although Margaret Power wrote in her 1991 book ''The Egalitarians'' that the field studies from which the aggressive data came, Gombe and Mahale, used artificial feeding systems that increased aggression in the chimpanzee populations studied. Thus, the behaviour may not reflect innate characteristics of the species as a whole.<ref name="Power.Anthropologist"/> In the years following her artificial feeding conditions at Gombe, Jane Goodall described groups of male chimpanzees patrolling the borders of their territory, brutally attacking chimpanzees that had split off from the Gombe group. A study published in 2010 found that the chimpanzees wage wars over territory, not mates.<ref>{{cite news |date=24 June 2010 |title=Killer instincts |newspaper=[[The Economist]] |url=https://www.economist.com/science-and-technology/2010/06/24/killer-instincts |url-access=registration |access-date=21 December 2023 |archive-date=21 December 2023 |archive-url=https://web.archive.org/web/20231221154203/https://www.economist.com/science-and-technology/2010/06/24/killer-instincts |url-status=live }}</ref> Patrols from smaller groups are more likely to avoid contact with their neighbours. Patrols from large groups even take over a smaller group's territory, gaining access to more resources, food, and females.<ref name="Nishida1986"/>{{sfn|Goodall|1986|pp=491, 528}} While it was traditionally accepted that only female chimpanzees immigrate and males remain in their natal troop for life, there are confirmed cases of adult males safely integrating themselves into new communities among West African chimpanzees, suggesting they are less territorial than other subspecies.<ref>{{Cite journal |last1=Sugiyama |first1=Y. |last2=Koman |first2=J. |date=1979 |title=Social structure and dynamics of wild chimpanzees at Bossou, Guinea |journal=Primates |volume=20 |issue=3 |pages=323–339 |doi=10.1007/BF02373387 |s2cid=9267686 |issn=1610-7365}}</ref>

===Mating and parenting===
[[File:Gombe Stream NP Mutter und Kind.jpg|thumb|upright|Infant and mother]]
Chimpanzees mate throughout the year, although the number of females in [[oestrus]] varies seasonally in a group.<ref name="Wallis2002">{{cite book |author=Wallis, J. |date=2002 |chapter=Seasonal aspects of reproduction and sexual behavior in two chimpanzee populations: a comparison of Gombe (Tanzania) and Budongo (Uganda) |pages=181–191 |editor=Boesch, C. |editor2=Hohmann, G. |editor3=Marchant, L. F. |title=Behavioural diversity in chimpanzees and bonobos |location=Cambridge, UK |publisher=Cambridge University Press |isbn=978-0-521-00613-2}}</ref> Female chimpanzees are more likely to come into oestrus when food is readily available. Oestrous females exhibit [[sexual swelling]]s. Chimpanzees are [[promiscuous]]: during oestrus, females mate with several males in their community, while males have large testicles for [[sperm competition]]. Other forms of mating also exist. A community's dominant males sometimes restrict reproductive access to females. A male and female can form a consortship and mate outside their community. In addition, females sometimes leave their community and mate with males from neighboring communities.{{sfn|Goodall|1986|pp=450–451}}<ref name="Gagneux1999">{{cite journal |author=Gagneux, P. |author2=Boesch, C. |author3=Woodruff, D. S. |s2cid=25981874 |title=Female reproductive strategies, paternity and community structure in wild West African chimpanzees |journal=Animal Behaviour |volume=57 |issue=1 |pages=19–32 |date=1999 |pmid=10053068 |doi=10.1006/anbe.1998.0972}}</ref> These [[alternative mating strategy|alternative mating strategies]] give females more mating opportunities without losing the support of the males in their community.<ref name="Gagneux1999"/> [[Infanticide in primates|Infanticide]] has been recorded in chimpanzee communities in some areas, and the victims are often consumed. Male chimpanzees practice infanticide on unrelated young to shorten the interbirth intervals in the females.<ref>{{cite journal |author1=Watts, D. P. |author2=Mitani, J. C. |year=2000 |title=Infanticide and cannibalism by male chimpanzees at Ngogo, Kibale National Park, Uganda |journal=Primates |volume=41 |issue=4 |pages=357–365 |doi=10.1007/BF02557646 |pmid=30545199 |s2cid=22595511}}</ref><ref name="Goodall1977">{{cite journal |author=Goodall, J. |author-link=Jane Goodall |title=Infant killing and cannibalism in free-living chimpanzees |journal=Folia Primatologica; International Journal of Primatology |volume=28 |issue=4 |pages=259–89 |year=1977 |pmid=564321 |doi=10.1159/000155817}}</ref> Females sometimes practice infanticide. This may be related to the dominance hierarchy in females or may simply be pathological.<ref name="Pusey1997">{{cite journal |author1=Pusey, A. |author2=Williams, J. |author3=Goodall, J. |author3-link=Jane Goodall |title=The influence of dominance rank on the reproductive success of female chimpanzees |journal=Science |volume=277 |issue=5327 |pages=828–831 |date=August 1997 |pmid=9242614 |doi=10.1126/science.277.5327.828}}</ref>

[[Inbreeding]] was studied in a relatively undisturbed eastern chimpanzee community that displayed substantial bisexual philopatry.<ref name = White2024>{{cite journal |last1=White |first1=LC |last2=Städele |first2=V |last3=Ramirez Amaya |first3=S |last4=Langergraber |first4=K |last5=Vigilant |first5=L |title=Female chimpanzees avoid inbreeding even in the presence of substantial bisexual philopatry |journal=R Soc Open Sci |date=17 January 2024 |volume=11 |issue=1 |page=230967 |doi=10.1098/rsos.230967 |pmid=38234436 |pmc=10791533|bibcode=2024RSOS...1130967W }}</ref> Despite an increased inbreeding risk incurred by females who do not disperse before reaching reproductive age, these females were still able to [[Inbreeding avoidance|avoid]] producing inbred offspring.<ref name = White2024/>

[[Copulation (zoology)|Copulation]] is brief, lasting approximately seven seconds.<ref name="Dixson2012">{{cite book |first=A. F. |last=Dixson |title=Primate Sexuality: Comparative Studies of the Prosimians, Monkeys, Apes, and Humans |date=2012 |publisher=OUP Oxford |isbn=978-0-19-150342-9}}</ref> The [[gestation]] period is eight months.<ref name="Estes"/> Care for the young is provided mostly by their mothers. The survival and emotional health of the young is dependent on maternal care. Mothers provide their young with food, warmth, and protection, and teach them certain skills. In addition, a chimpanzee's future rank may be dependent on its mother's status.{{sfn|Goodall|1986|pp=203–205}}<ref name="Foerster Franz Murray Gilby">{{cite journal |last1=Foerster |first1=S. |last2=Franz |first2=M. |last3=Murray |first3=C. M. |last4=Gilby |first4=I. C. |last5=Feldblum |first5=J. T. |last6=Walker |first6=K. K. |last7=Pusey |first7=A. E. |title=Chimpanzee females queue but males compete for social status |journal=Scientific Reports |volume=6 |issue=1 |date=2016 |doi=10.1038/srep35404 |pmid=27739527 |pmc=5064376 |page=35404 |bibcode=2016NatSR...635404F}}</ref> Male chimpanzees continue to associate with the females they impregnated and interact with and support their offspring.<ref>{{cite journal|last1=Murray|first1=C. M.|last2=Stanton|first2=M. A.|last3=Lonsdorf|first3=E. V.|last4=Wroblewski|first4=E. E.|last5=Pusey|first5=A. E.|year=2016|title=Chimpanzee fathers bias their behaviour towards their offspring|journal=Royal Society Open Science|volume=3|issue=11|page=160441 |doi=10.1098/rsos.160441|pmid=28018626 |pmc=5180124 |bibcode=2016RSOS....360441M }}</ref> Newborn chimpanzees are helpless. For example, their grasping reflex is not strong enough to support them for more than a few seconds. For their first 30 days, infants cling to their mother's bellies. Infants are unable to support their own weight for their first two months and need their mothers' support.<ref name="Bard1995">{{cite book |last=Bard |first=K. A. |editor-last=Bornstein |editor-first=M. H. |title=Handbook of Parenting |volume=2 |chapter=Parenting in nonhuman primates |publisher=Routledge, Taylor & Francis Group |location=New York |year=2019 |orig-date=1995 |isbn=978-0-429-68588-0 |oclc=1089683467}}</ref>

When they reach five to six months, infants ride on their mothers' backs. They remain in continual contact for the rest of their first year. When they reach two years of age, they are able to move and sit independently and start moving beyond the arms' reach of their mothers. By four to six years, chimpanzees are weaned and infancy ends. The juvenile period for chimpanzees lasts from their sixth to ninth years. Juveniles remain close to their mothers, but interact an increasing amount with other members of their community. Adolescent females move between groups and are supported by their mothers in agonistic encounters. Adolescent males spend time with adult males in social activities like hunting and boundary patrolling.<ref name="Bard1995"/> A captive study suggests males can safely immigrate to a new group if accompanied by immigrant females who have an existing relationship with this male. This gives the resident males reproductive advantages with these females, as they are more inclined to remain in the group if their male friend is also accepted.<ref>{{Cite journal |last1=Goetschi |first1=F. |last2=McClung |first2=J. |last3=Baumeyer |first3=A. |last4=Zuberbuhler |first4=K. |date=2020-02-01 |title=Chimpanzee immigration: complex social strategies differ between zoo-based and wild animals |journal=Journal of Zoo and Aquarium Research |volume=8 |issue=1 |doi=10.19227/jzar.v8i1.326 |hdl=10023/19397 |issn=2214-7594}}</ref>

===Communication===
{{listen|filename=Pant-hoot call made by a male chimpanzee.ogg|title=Pant-hoot call|description=Pant-hoot call made by an adult male, demonstrating the introduction, build-up, climax, and let-down phases.<ref name="Fedurek">{{Cite journal |last1=Fedurek |first1=P. |last2=Zuberbühler |first2=K. |last3=Semple |first3=S. |date=2017 |title=Trade-offs in the production of animal vocal sequences: insights from the structure of wild chimpanzee pant hoots |journal=Frontiers in Zoology |volume=14 |pages=50 |doi=10.1186/s12983-017-0235-8 |pmc=5674848 |pmid=29142585 |doi-access=free }}</ref>|format=[[Vorbis]]}}
Chimpanzees use facial expressions, postures, and sounds to communicate with each other. Chimpanzees have expressive faces that are important in close-up communications. When frightened, a "full closed grin" causes nearby individuals to be fearful, as well. Playful chimpanzees display an open-mouthed grin. Chimpanzees may also express themselves with the "pout", which is made in distress, the "sneer", which is made when threatening or fearful, and "compressed-lips face", which is a type of display. When submitting to a dominant individual, a chimpanzee crunches, bobs, and extends a hand. When in an aggressive mode, a chimpanzee swaggers bipedally, hunched over and arms waving, in an attempt to exaggerate its size.{{sfn|Goodall|1986|pp=119–122}} While travelling, chimpanzees keep in contact by beating their hands and feet against the trunks of large trees, an act that is known as "drumming". They also do this when encountering individuals from other communities.<ref name="Crockford2005">{{cite journal |last1=Crockford |first1=C. |last2=Boesch |first2=C. |s2cid=84677208 |year=2005 |title=Call combinations in wild chimpanzees |journal=Behaviour |volume=142 |issue=4 |pages=397–421 |doi=10.1163/1568539054012047}}</ref>

Vocalisations are also important in chimpanzee communication. The most common call in adults is the "[[Pant-hoot (call)|pant-hoot]]", which may signal social rank and bond along with keeping groups together. Pant-hoots are made of four parts, starting with soft "hoos", the introduction; that gets louder and louder, the build-up; and climax into screams and sometimes barks; these die down back to soft "hoos" during the letdown phase as the call ends.<ref name="Fedurek"/><ref name="Crockford2005"/> Grunting is made in situations like feeding and greeting.<ref name="Crockford2005"/> Submissive individuals make "pant-grunts" towards their superiors.<ref name="Pusey1997"/>{{sfn|Goodall|1986|p=129}} Whimpering is made by young chimpanzees as a form of begging or when lost from the group.<ref name="Crockford2005"/> Chimpanzees use distance calls to draw attention to danger, food sources, or other community members.{{sfn|Goodall|1986|pp=132–133}} "Barks" may be made as "short barks" when hunting and "tonal barks" when sighting large snakes.<ref name="Crockford2005"/>
[[File:Gombe Stream NP Beute.jpg|thumb|Adult male eastern chimpanzee snatches a dead [[bushbuck antelope]] from a baboon in [[Gombe Stream National Park]].]]

===Hunting===
When hunting small monkeys such as the [[Western red colobus|red colobus]], chimpanzees hunt where the forest canopy is interrupted or irregular. This allows them to easily corner the monkeys when chasing them in the appropriate direction. Chimpanzees may also hunt as a coordinated team, so that they can corner their prey even in a continuous canopy. During an [[arboreal]] hunt, each chimpanzee in the hunting groups has a role. "Drivers" serve to keep the prey running in a certain direction and follow them without attempting to make a catch. "Blockers" are stationed at the bottom of the trees and climb up to block prey that takes off in a different direction. "Chasers" move quickly and try to make a catch. Finally, "ambushers" hide and rush out when a monkey nears.<ref name="Leipzig2002">{{cite journal |author=Boesch, C. |title=Cooperative hunting roles among Taï chimpanzees |journal=Human Nature |volume=13 |issue=1 |pages=27–46 |year=2002 |pmid=26192594 |doi=10.1007/s12110-002-1013-6 |citeseerx=10.1.1.556.2265|s2cid=15905236}}</ref> While both adults and infants are taken, adult male colobus monkeys will attack the hunting chimps.{{sfn|Goodall|1986|pp=273–274}} When caught and killed, the meal is distributed to all hunting party members and even bystanders.<ref name="Leipzig2002"/>

Male chimpanzees hunt in groups more than females. Female chimpanzees tend to hunt solitarily. If a female chimpanzee were to participate in the hunting group and catch a Red Colobus, it would likely immediately be taken by an adult male. Female chimpanzees are estimated to hunt ≈ 10-15% of a community's vertebrates.<ref>{{Cite journal |last1=Gilby |first1=Ian C. |last2=Machanda |first2=Zarin P. |last3=O’Malley |first3=Robert C. |last4=Murray |first4=Carson M. |last5=Lonsdorf |first5=Elizabeth V. |last6=Walker |first6=Kara |last7=Mjungu |first7=Deus C. |last8=Otali |first8=Emily |last9=Muller |first9=Martin N. |last10=Thompson |first10=Melissa Emery |last11=Pusey |first11=Anne E. |last12=Wrangham |first12=Richard W. |date=September 2017 |title=Predation by female chimpanzees: toward an understanding of sex differences in meat acquisition in the last common ancestor of Pan and Homo |journal=Journal of Human Evolution |volume=110 |pages=82–94 |doi=10.1016/j.jhevol.2017.06.015 |issn=0047-2484 |pmc=5570454 |pmid=28778463|bibcode=2017JHumE.110...82G }}</ref>

=== Wound care ===
A 2022 study reported that chimpanzees crushed and applied insects to their own wounds and the wounds of other chimpanzees.<ref>{{cite web | url=https://www.theguardian.com/world/2022/feb/08/chimpanzees-observed-treating-wounds-of-others-using-crushed-insects | title=Chimpanzees observed treating wounds of others, using crushed insects | work=The Guardian | date=8 February 2022 | last1=France-Presse | first1=Agence }}</ref>