Editing Aggression (section)

===Between species and groups===
The most apparent type of [[interspecific]] aggression is that observed in the interaction between a [[predator]] and its [[prey]]. However, according to many researchers, [[predation]] is not aggression. A cat does not hiss or arch its back when pursuing a rat, and the active areas in its [[hypothalamus]] resemble those that reflect hunger rather than those that reflect aggression.<ref>Gleitman, Henry, Alan J. Fridlund, and Daniel Reisberg. Psychology. 6th ed. New York: W W Norton and Company, 2004. 431–432.</ref> However, others refer to this behavior as predatory aggression, and point out cases that resemble hostile behavior, such as mouse-killing by rats.<ref>Gendreau, PL & Archer, J. 'Subtypes of Aggression in Humans and Animals', in [https://books.google.com/books/about/Developmental_origins_of_aggression.html?id=XmSfJEl2v4sC Developmental Origins of Aggression], 2005, The Guilford Press.</ref> In [[aggressive mimicry]] a predator has the appearance of a harmless organism or object attractive to the prey; when the prey approaches, the predator attacks.

An animal defending against a predator may engage in either "[[Fight-or-flight response|fight or flight]]" or "[[tend and befriend]]" in response to predator attack or threat of attack, depending on its estimate of the predator's strength relative to its own. Alternative defenses include a range of [[antipredator adaptation]]s, including [[alarm signal]]s. An example of an alarm signal is Nerol, a chemical which is found in the mandibular glands of ''[[Trigona fulviventris]]'' individuals.<ref name=":0">{{cite journal |doi=10.1007/BF00990750 |pmid=24413960 |title=Nerol: An alarm substance of the stingless bee, Trigona fulviventris (Hymenoptera: Apidae) |journal=Journal of Chemical Ecology |volume=8 |issue=9 |pages=1167–81 |year=1982 |last1=Johnson |first1=L. K. |last2=Wiemer |first2=D. F. |bibcode=1982JCEco...8.1167J |s2cid=25056451 }}</ref> Release of Nerol by T. fulviventris individuals in the nest has been shown to decrease the number of individuals leaving the nest by fifty percent, as well as increasing aggressive behaviors like biting.<ref name=":0" /> Alarm signals like nerol can also act as attraction signals; in T. fulviventris, individuals that have been captured by a predator may release nerol to attract nest mates, who will proceed to attack or bite the predator.<ref name=":0" />

Aggression between groups is determined partly by willingness to fight, which depends on a number of factors including numerical advantage, distance from home territories, how often the groups encounter each other, competitive abilities, differences in body size, and whose territory is being invaded.<ref>{{cite journal |doi=10.1016/j.jebo.2017.05.004 |title=The logic of animal intergroup conflict: A review |journal=Journal of Economic Behavior and Organization |year=2017 |last1=Rusch |first1=H. |last2=Gavrilets |first2=S.|volume=178 |pages=1014–1030 |s2cid=49359988 |doi-access=free }}</ref> Also, an individual is more likely to become aggressive if other aggressive group members are nearby.<ref>{{cite journal |doi=10.1098/rspb.2006.3626 |pmid=17015327 |pmc=1635503 |jstor=25223670 |title=Numerical assessment affects aggression and competitive ability: A team-fighting strategy for the ant Formica xerophila |journal=Proceedings of the Royal Society B: Biological Sciences |volume=273 |issue=1602 |pages=2737–42 |year=2006 |last1=Tanner |first1=C. J }}</ref> One particular phenomenon – the formation of coordinated coalitions that raid neighboring territories to kill [[conspecific]]s – has only been documented in two species in the animal kingdom: [[Common chimpanzee|'common' chimpanzees]] and [[humans]].<ref>{{cite journal |doi=10.1016/j.cub.2010.04.021 |pmid=20620900 |title=Lethal intergroup aggression leads to territorial expansion in wild chimpanzees |journal=Current Biology |volume=20 |issue=12 |pages=R507–8 |year=2010 |last1=Mitani |first1=John C. |last2=Watts |first2=David P. |last3=Amsler |first3=Sylvia J. |s2cid=6493161 |doi-access=free |bibcode=2010CBio...20.R507M }}</ref>