Editing Reciprocal altruism (section)

==Regulation by emotional disposition==
In comparison to that of other animals, the human altruistic system is a sensitive and unstable one.<ref name="trivers" /> Therefore, the tendency to give, to cheat, and the response to other's acts of giving and cheating must be regulated by a complex psychology in each individual, social structures, and cultural traditions. Individuals differ in the degree of these tendencies and responses.
According to Trivers, the following emotional dispositions and their evolution can be understood in terms of regulation of altruism.<ref name="trivers" />

*Friendship and emotions of liking and disliking.
*Moralistic aggression. A protection mechanism from cheaters acts to regulate the advantage of cheaters in selection against altruists. The moralistic altruist may want to educate or even punish a cheater.
*Gratitude and sympathy. A fine regulation of altruism can be associated with gratitude and sympathy in terms of cost/benefit and the level in which the beneficiary will reciprocate.
*Guilt and reparative altruism. Prevents the cheater from cheating again. The cheater shows regret to avoid paying too dearly for past acts.
*Subtle cheating. A stable evolutionary equilibrium could include a low percentage of mimics in controversial support of adaptive sociopathy.
*Trust and suspicion. These are regulators for cheating and subtle cheating.
*Partnerships. Altruism to create friendships.

It is not known how individuals pick partners as there has been little research on choice. Modeling indicates that altruism about partner choices is unlikely to evolve, as costs and benefits between multiple individuals are variable.<ref>{{cite journal | last1 = Schino | first1 = G. | last2 = Aureli | first2 = F. | year = 2010 | title = A few misunderstandings about reciprocal altruism | journal = Commun. Integr. Biol. | volume = 3 | issue = 6| pages = 561–3 | doi = 10.4161/cib.3.6.12977 | pmid = 21331239 | pmc=3038063}}</ref> Therefore, the time or frequency of reciprocal actions contributes more to an individual's choice of partner than the reciprocal act itself.