Editing Mammal (section)

===Social structure===
{{Main| Social animal}}
[[File:Borneo elephants.png|thumb|Female elephants live in stable groups, along with their offspring]]
[[Eusociality]] is the highest level of social organisation. These societies have an overlap of adult generations, the division of reproductive labour and cooperative caring of young. Usually insects, such as [[bee]]s, ants and termites, have eusocial behaviour, but it is demonstrated in two rodent species: the naked mole-rat<ref>{{cite journal | vauthors = Jarvis JU | title = Eusociality in a mammal: cooperative breeding in naked mole-rat colonies | journal = Science | volume = 212 | issue = 4494 | pages = 571–573 | date = May 1981 | pmid = 7209555 | doi = 10.1126/science.7209555 | bibcode = 1981Sci...212..571J | jstor = 1686202 | s2cid = 880054 }}</ref> and the [[Damaraland mole-rat]].<ref>{{cite journal | vauthors = Jacobs DS, Bennett NC, Jarvis JU, Crowe TM | year=1991 | title= The colony structure and dominance hierarchy of the Damaraland mole-rat, ''Cryptomys damarensis'' (Rodentia: Bathyergidae) from Namibia | journal=Journal of Zoology | volume=224 | issue=4 | pages=553–576 | doi=10.1111/j.1469-7998.1991.tb03785.x }}</ref>

Presociality is when animals exhibit more than just sexual interactions with members of the same species, but fall short of qualifying as eusocial. That is, presocial animals can display communal living, cooperative care of young, or primitive division of reproductive labour, but they do not display all of the three essential traits of eusocial animals. Humans and some species of [[Callitrichidae]] ([[marmoset]]s and [[tamarin]]s) are unique among primates in their degree of cooperative care of young.<ref>{{cite book| vauthors = Hardy SB | year=2009| title=Mothers and Others: The Evolutionary Origins of Mutual Understanding| publisher=Belknap Press of Harvard University Press| pages=92–93| url={{Google books| plainurl=yes| id=dsiksDFQPDsC| page=92}}| location=Boston}}</ref> [[Harry Harlow]] set up an experiment with [[rhesus monkey]]s, presocial primates, in 1958; the results from this study showed that social encounters are necessary in order for the young monkeys to develop both mentally and sexually.<ref name=Harlow71>{{cite journal | vauthors = Harlow HF, Suomi SJ | title = Social recovery by isolation-reared monkeys | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 68 | issue = 7 | pages = 1534–1538 | date = July 1971 | pmid = 5283943 | pmc = 389234 | doi = 10.1073/pnas.68.7.1534 | bibcode = 1971PNAS...68.1534H | doi-access = free }}</ref>

A [[fission–fusion society]] is a society that changes frequently in its size and composition, making up a permanent social group called the "parent group". Permanent social networks consist of all individual members of a community and often varies to track changes in their environment. In a fission–fusion society, the main parent group can fracture (fission) into smaller stable subgroups or individuals to adapt to [[Social environment|environmental]] or social circumstances. For example, a number of males may break off from the main group in order to hunt or forage for food during the day, but at night they may return to join (fusion) the primary group to share food and partake in other activities. Many mammals exhibit this, such as primates (for example orangutans and [[spider monkey]]s),<ref>{{cite journal | vauthors = van Schaik CP | title = The socioecology of fission–fusion sociality in Orangutans | journal = Primates; Journal of Primatology | volume = 40 | issue = 1 | pages = 69–86 | date = January 1999 | pmid = 23179533 | doi = 10.1007/BF02557703 | s2cid = 13366732 }}</ref> elephants,<ref>{{cite journal | vauthors = Archie EA, Moss CJ, Alberts SC | title = The ties that bind: genetic relatedness predicts the fission and fusion of social groups in wild African elephants | journal = Proceedings. Biological Sciences | volume = 273 | issue = 1586 | pages = 513–522 | date = March 2006 | pmid = 16537121 | pmc = 1560064 | doi = 10.1098/rspb.2005.3361 }}</ref> [[spotted hyena]]s,<ref>{{cite journal| vauthors = Smith JE, Memenis SK, Holekamp KE | title=Rank-related partner choice in the fission–fusion society of the spotted hyena (''Crocuta crocuta'')| journal=Behavioral Ecology and Sociobiology| year=2007| volume=61| issue=5| pages=753–765| doi=10.1007/s00265-006-0305-y| bibcode=2007BEcoS..61..753S| s2cid=24927919| url=https://www.mills.edu/academics/faculty/bio/jesmith/partner.pdf| url-status=dead| archive-url=https://web.archive.org/web/20140425002800/http://www.mills.edu/academics/faculty/bio/jesmith/partner.pdf| archive-date=25 April 2014}}</ref> lions,<ref>{{cite journal | vauthors = Matoba T, Kutsukake N, Hasegawa T | title = Head rubbing and licking reinforce social bonds in a group of captive African lions, Panthera leo | journal = PLOS ONE | volume = 8 | issue = 9 | pages = e73044 | year = 2013 | pmid = 24023806 | pmc = 3762833 | doi = 10.1371/journal.pone.0073044 | bibcode = 2013PLoSO...873044M | veditors = Hayward M | doi-access = free }}</ref> and dolphins.<ref>{{cite journal | vauthors = Krützen M, Barré LM, Connor RC, Mann J, Sherwin WB | title = 'O father: where art thou?' – Paternity assessment in an open fission–fusion society of wild bottlenose dolphins (Tursiops sp.) in Shark Bay, Western Australia | journal = Molecular Ecology | volume = 13 | issue = 7 | pages = 1975–1990 | date = July 2004 | pmid = 15189218 | doi = 10.1111/j.1365-294X.2004.02192.x | bibcode = 2004MolEc..13.1975K | s2cid = 4510393 }}</ref>

Solitary animals defend a territory and avoid social interactions with the members of its species, except during breeding season. This is to avoid resource competition, as two individuals of the same species would occupy the same niche, and to prevent depletion of food.<ref>{{cite book| url={{Google books | plainurl=yes | id=Nb21BwAAQBAJ| page=114}} | vauthors = Martin C | year=1991 | title=The Rainforests of West Africa: Ecology – Threats – Conservation | publisher=Springer | doi=10.1007/978-3-0348-7726-8| isbn=978-3-0348-7726-8}}</ref> A solitary animal, while foraging, can also be less conspicuous to predators or prey.<ref>{{cite journal | vauthors = le Roux A, Cherry MI, Gygax L | title=Vigilance behaviour and fitness consequences: comparing a solitary foraging and an obligate group-foraging mammal| journal=Behavioral Ecology and Sociobiology | date=5 May 2009 | volume=63 | issue=8 | pages=1097–1107 | doi=10.1007/s00265-009-0762-1| bibcode=2009BEcoS..63.1097L| s2cid=21961356 }}</ref>

[[File:Fighting red kangaroos 2.jpg|thumb|left|[[Red kangaroo]]s "boxing" for [[dominance hierarchy|dominance]]]]

In a [[dominance hierarchy|hierarchy]], individuals are either dominant or submissive. A despotic hierarchy is where one individual is dominant while the others are submissive, as in wolves and lemurs,<ref>{{cite journal | vauthors = Palagi E, Norscia I | title = The Season for Peace: Reconciliation in a Despotic Species (Lemur catta) | journal = PLOS ONE | volume = 10 | issue = 11 | pages = e0142150 | year = 2015 | pmid = 26569400 | pmc = 4646466 | doi = 10.1371/journal.pone.0142150 | bibcode = 2015PLoSO..1042150P | veditors = Samonds KE | doi-access = free }}</ref> and a [[pecking order]] is a linear ranking of individuals where there is a top individual and a bottom individual. Pecking orders may also be ranked by sex, where the lowest individual of a sex has a higher ranking than the top individual of the other sex, as in hyenas.<ref>{{cite journal| vauthors = East ML, Hofer H | year=2000 | title=Male spotted hyenas (''Crocuta crocuta'') queue for status in social groups dominated by females | journal=Behavioral Ecology | volume=12 | issue=15| pages=558–568 | doi=10.1093/beheco/12.5.558| doi-access=free }}</ref> Dominant individuals, or alphas, have a high chance of reproductive success, especially in [[harem (zoology)|harems]] where one or a few males (resident males) have exclusive breeding rights to females in a group.<ref>{{cite journal |author2-link=Joan Silk | vauthors = Samuels A, Silk JB, Rodman P | year=1984 | title=Changes in the dominance rank and reproductive behavior of male bonnet macaques (''Macaca radiate'')| journal=Animal Behaviour | volume=32 | issue=4 | pages=994–1003 | doi=10.1016/s0003-3472(84)80212-2| s2cid=53186523 }}</ref> Non-resident males can also be accepted in harems, but some species, such as the [[common vampire bat]] (''Desmodus rotundus''), may be more strict.<ref>{{cite journal | vauthors = Delpietro HA, Russo RG | year=2002 | title=Observations of the common vampire bat (''Desmodus rotundus'') and the hairy-legged vampire bat (''Diphylla ecaudata'') in captivity | journal=[[Mammalian Biology]] | volume=67 | issue=2 | pages=65–78 | doi=10.1078/1616-5047-00011| bibcode=2002MamBi..67...65D }}</ref>

Some mammals are perfectly [[Monogamy in animals|monogamous]], meaning that they [[pair bond|mate for life]] and take no other partners (even after the original mate's death), as with wolves, [[Eurasian beaver]]s, and otters.<ref>{{cite journal | vauthors = Kleiman DG | title = Monogamy in mammals | journal = The Quarterly Review of Biology | volume = 52 | issue = 1 | pages = 39–69 | date = March 1977 | pmid = 857268 | doi = 10.1086/409721 | s2cid = 25675086 }}</ref><ref>{{cite journal | vauthors = Holland B, Rice WR | journal = Evolution; International Journal of Organic Evolution | volume = 52 | issue = 1 | pages = 1–7 | date = February 1998 | pmid = 28568154 | doi = 10.2307/2410914 | url = https://wolfweb.unr.edu/homepage/jaz/eecb752/lecture06/Holland%26Rice1998.pdf | jstor = 2410914 | title = Perspective: Chase-Away Sexual Selection: Antagonistic Seduction Versus Resistance | access-date = 8 July 2016 | archive-url = https://web.archive.org/web/20190608065427/https://wolfweb.unr.edu/homepage/jaz/eecb752/lecture06/Holland%26Rice1998.pdf | archive-date = 8 June 2019 | url-status = dead }}</ref> There are three types of polygamy: either one or multiple dominant males have breeding rights ([[polygyny in animals|polygyny]]), multiple males that females mate with (polyandry), or multiple males have exclusive relations with multiple females ([[polygynandry]]). It is much more common for polygynous mating to happen, which, excluding [[lek mating|leks]], are estimated to occur in up to 90% of mammals.<ref>{{cite journal | vauthors = Clutton-Brock TH | title = Mammalian mating systems | journal = Proceedings of the Royal Society of London. Series B, Biological Sciences | volume = 236 | issue = 1285 | pages = 339–372 | date = May 1989 | pmid = 2567517 | doi = 10.1098/rspb.1989.0027 | bibcode = 1989RSPSB.236..339C | s2cid = 84780662 | url = https://zenodo.org/record/8204699 }}</ref> Lek mating occurs when males congregate around females and try to attract them with various [[courtship display]]s and vocalisations, as in harbour seals.<ref>{{cite journal| vauthors = Boness DJ, Bowen D, Buhleier BM, Marshall GJ | year=2006 | title=Mating tactics and mating system of an aquatic-mating pinniped: the harbor seal, ''Phoca vitulina'' | journal=Behavioral Ecology and Sociobiology | volume=61 | issue=1 | pages=119–130 | doi=10.1007/s00265-006-0242-9 | bibcode=2006BEcoS..61..119B | s2cid=25266746 | url=https://www.researchgate.net/publication/226692255}}</ref>

All [[higher mammal]]s (excluding monotremes) share two major adaptations for care of the young: live birth and lactation. These imply a group-wide choice of a degree of [[parental care]]. They may build nests and dig burrows to raise their young in, or feed and guard them often for a prolonged period of time. Many mammals are [[K-selected]], and invest more time and energy into their young than do [[r-selected]] animals. When two animals mate, they both share an interest in the success of the offspring, though often to different extremes. Mammalian females exhibit some degree of maternal aggression, another example of parental care, which may be targeted against other females of the species or the young of other females; however, some mammals may "aunt" the infants of other females, and care for them. Mammalian males may play a role in child rearing, as with [[tenrec]]s, however this varies species to species, even within the same genus. For example, the males of the [[southern pig-tailed macaque]] (''Macaca nemestrina'') do not participate in child care, whereas the males of the [[Japanese macaque]] (''M. fuscata'') do.<ref>{{cite book|chapter-url={{Google books|plainurl=yes|id=ipjhBwAAQBAJ|page=1}}|chapter=Origins of Parental Care| vauthors = Klopfer PH |year=1981 | veditors = Gubernick DJ |title=Parental Care in Mammals|publisher=Plenum Press|location=New York|isbn=978-1-4613-3150-6|oclc=913709574}}</ref>