Editing Altruism (section)

==Scientific viewpoints<!--linked from 'Evolution of morality'-->==

===Anthropology===
{{expand section|date=July 2023}}
{{See also|Alms|Altruism (ethics)}}
[[Marcel Mauss]]'s essay ''[[The Gift (essay)|The Gift]]'' contains a passage called "Note on alms". This note describes the evolution of the notion of alms (and by extension of altruism) from the notion of sacrifice. In it, he writes:

{{blockquote|Alms are the fruits of a moral notion of the gift and of fortune on the one hand, and of a notion of sacrifice, on the other. Generosity is an obligation, because Nemesis avenges the poor and the gods for the superabundance of happiness and wealth of certain people who should rid themselves of it. This is the ancient morality of the gift, which has become a principle of justice. The gods and the spirits accept that the share of wealth and happiness that has been offered to them and had been hitherto destroyed in useless sacrifices should serve the poor and children.}}

===Evolutionary explanations===
{{Main|Altruism (biology)|Evolution of morality|Evolutionary ethics}}
[[File:Manner of Francis Wheatley, Giving alms to beggar children.jpg|thumb|upright|Giving alms to beggar children]]
In [[ethology]] (the scientific study of animal behaviour), and more generally in the study of [[Sociocultural evolution|social evolution]], altruism refers to behavior by an individual that increases the [[fitness (biology)|fitness]] of another individual while decreasing the fitness of the actor.<ref name="Bell2008">{{cite book| last = Bell| first = Graham| title = Selection: the mechanism of evolution| url = https://archive.org/details/selectionmechani00bell_664| url-access = limited| year = 2008| publisher = Oxford University Press| location = Oxford| isbn = 978-0-19-856972-5| pages = [https://archive.org/details/selectionmechani00bell_664/page/n381 367]–368 }}</ref> In [[evolutionary psychology]] this term may be applied to a wide range of human behaviors such as [[Charity (practice)|charity]], [[emergency aid]], help to coalition partners, [[Gratuity|tipping]], [[courtship]] gifts, production of [[Public good (economics)|public good]]s, and [[environmentalism]].<ref name="AEP1">{{Cite book | first=Pat|last=Barcaly| chapter=The evolution of charitable behaviour and the power of reputation|editor-last1 = Roberts | editor-first1 = S. Craig | doi = 10.1093/acprof:oso/9780199586073.001.0001 | title = Applied Evolutionary Psychology | year = 2011 | publisher = Oxford University Press| isbn = 978-0-19-958607-3 }}</ref>

The need for an explanation of altruistic behavior that is compatible with evolutionary origins has driven the development of new theories. Two related strands of research on altruism have emerged from traditional evolutionary analyses and [[evolutionary game theory]]: a mathematical model and analysis of behavioral strategies.

Some of the proposed mechanisms are: 
* [[Kin selection]].<ref>{{cite encyclopedia|title=Biological Altruism|chapter=Kin Selection and Inclusive Fitness|chapter-url=https://plato.stanford.edu/entries/altruism-biological/#KinSelIncFit|encyclopedia=Stanford Encyclopedia of Philosophy|last=Okasha|first=Samir|year=2013}}</ref> That animals and humans are more altruistic towards close kin than to distant kin and non-kin has been confirmed in numerous studies across many different cultures. Even subtle cues indicating kinship may unconsciously increase altruistic behavior. One kinship cue is facial resemblance. One study found that slightly altering photographs to resemble the faces of study participants more closely increased the trust the participants expressed regarding depicted persons. Another cue is having the same family name, especially if rare, which has been found to increase helpful behavior. Another study found more cooperative behavior, the greater the number of perceived kin in a group. Using kinship terms in political speeches increased audience agreement with the speaker in one study. This effect was powerful for firstborns, who are typically close to their families.<ref name=AEP1/>
* Vested interests. People are likely to suffer if their friends, allies and those from similar social [[ingroup]]s suffer or disappear. Helping such group members may, therefore, also benefit the altruist. Making ingroup membership more noticeable increases cooperativeness. Extreme self-sacrifice towards the ingroup may be adaptive if a hostile [[Ingroups and outgroups|outgroup]] threatens the entire ingroup.<ref name=AEP1/>
* [[Reciprocal altruism]].<ref>{{cite journal |last1=Trivers |first1=Robert L. |title=The Evolution of Reciprocal Altruism |journal=The Quarterly Review of Biology |date=March 1971 |volume=46 |issue=1 |pages=35–57 |doi=10.1086/406755 }}</ref> See also [[Reciprocity (evolution)]].
** Direct [[Reciprocity (social psychology)|reciprocity]].<ref>{{cite journal|doi=10.1126/science.7466396 |first1=R|last1=Axelrod|first2=W.D.|last2=Hamilton |title=The evolution of cooperation |journal=[[Science (journal)|Science]] |volume=211 |issue=4489 |date=27 March 1981 |pages=1390–1396 |pmid=7466396 |bibcode = 1981Sci...211.1390A|citeseerx=10.1.1.147.9644 }}</ref> Research shows that it can be beneficial to help others if there is a chance that they will reciprocate the help. The effective [[tit for tat]] strategy is one [[game theory|game theoretic]] example. Many people seem to be following a similar strategy by cooperating if and only if others cooperate in return.<ref name=AEP1/>
**:One consequence is that people are more cooperative with one another if they are more likely to interact again in the future. People tend to be less cooperative if they perceive that the frequency of helpers in the population is lower. They tend to help less if they see non-cooperativeness by others, and this effect tends to be stronger than the opposite effect of seeing cooperative behaviors. Simply changing the cooperative framing of a proposal may increase cooperativeness, such as calling it a "Community Game" instead of a "Wall Street Game".<ref name=AEP1/>
**:A tendency towards reciprocity implies that people feel obligated to respond if someone helps them. This has been used by charities that give small gifts to potential donors hoping to induce reciprocity. Another method is to announce publicly that someone has given a large donation. The tendency to reciprocate can even generalize, so people become more helpful toward others after being helped. On the other hand, people will avoid or even retaliate against those perceived not to be cooperating. People sometimes mistakenly fail to help when they intended to, or their helping may not be noticed, which may cause unintended conflicts. As such, it may be an optimal strategy to be slightly forgiving of and have a slightly generous interpretation of non-cooperation.<ref name=AEP1/>
**:People are more likely to cooperate on a task if they can communicate with one another first. This may be due to better cooperativeness assessments or promises exchange. They are more cooperative if they can gradually build trust instead of being asked to give extensive help immediately. Direct reciprocity and cooperation in a group can be increased by changing the focus and incentives from intra-group competition to larger-scale competitions, such as between groups or against the general population. Thus, giving grades and promotions based only on an individual's performance relative to a small local group, as is common, may reduce cooperative behaviors in the group.<ref name=AEP1/>
** Indirect reciprocity.<ref>{{cite journal |last1=Nowak |first1=Martin A. |last2=Sigmund |first2=Karl |title=Evolution of indirect reciprocity |journal=Nature |date=October 2005 |volume=437 |issue=7063 |pages=1291–1298 |doi=10.1038/nature04131 |pmid=16251955 |bibcode=2005Natur.437.1291N |url=http://pure.iiasa.ac.at/id/eprint/7763/1/IR-05-079.pdf }}</ref> Because people avoid poor reciprocators and cheaters, a person's [[reputation]] is important. A person esteemed for their reciprocity is more likely to receive assistance, even from individuals they have not directly interacted with before.<ref name=AEP1/>
** [[Strong reciprocity]].<ref>{{cite journal|last=Gintis |first=Herbert |author-link=Herbert Gintis|title=Strong Reciprocity and Human Sociality|journal=[[Journal of Theoretical Biology]]|volume=206|issue=2|date=September 2000|pmid=10966755|pages=169–179|doi=10.1006/jtbi.2000.2111|bibcode=2000JThBi.206..169G |hdl=10419/105717|hdl-access=free|citeseerx=10.1.1.335.7226 |s2cid=9260305 }}</ref> This form of reciprocity is expressed by people who invest more resources in cooperation and punishment than what is deemed optimal based on established theories of altruism.
** Pseudo-reciprocity.<ref>{{cite book | chapter=By-product Benefits, Reciprocity, and Pseudoreciprocity in Mutualism|editor-last=Hammerstein | editor-first=Peter | title=Genetic and Cultural Evolution of Cooperation | publisher=MIT Press | date=2003 |pages=203–222 | isbn=978-0-262-08326-3 | doi=10.7551/mitpress/3232.003.0013}}</ref> An organism behaves altruistically and the recipient does not reciprocate but has an increased chance of acting in a way that is selfish but also as a byproduct benefits the altruist.
* [[Signalling theory|Costly signaling]] and the [[handicap principle]].<ref>{{cite journal |last1=Zahavi |first1=Amotz |title=Altruism as a Handicap: The Limitations of Kin Selection and Reciprocity |journal=Journal of Avian Biology |date=1995 |volume=26 |issue=1 |pages=1–3 |doi=10.2307/3677205 |jstor=3677205 }}</ref> Altruism, by diverting resources from the altruist, can act as an "honest signal" of available resources and the skills to acquire them. This may signal to others that the altruist is a valuable potential partner. It may also signal interactive and cooperative intentions, since someone who does not expect to interact further in the future gains nothing from such costly signaling. While it's uncertain if costly signaling can predict long-term cooperative traits, people tend to trust helpers more. Costly signaling loses its value when everyone shares identical traits, resources, and cooperative intentions, but it gains significance as population variability in these aspects increases.<ref name=AEP1/>

:Hunters who [[Sharing|share]] meat display a costly signal of ability. The research found that good hunters have higher reproductive success and more adulterous relations even if they receive no more of the hunted meat than anyone else. Similarly, holding large feasts and giving large donations are ways of demonstrating one's resources. [[Hero]]ic risk-taking has also been interpreted as a costly signal of ability.<ref name=AEP1/>

[[File:FEMA - 15337 - Photograph by Andrea Booher taken on 09-10-2005 in Texas.jpg|thumb|Volunteers assist Hurricane victims at the [[Houston Astrodome]], following [[Hurricane Katrina]].]]
:Both indirect reciprocity and costly signaling depend on reputation value and tend to make similar predictions. One is that people will be more helpful when they know that their helping behavior will be communicated to people they will interact with later, publicly announced, discussed, or observed by someone else. This has been documented in many studies. The effect is sensitive to subtle cues, such as people being more helpful when there were stylized eyespots instead of a logo on a computer screen. {{dubious|reason=failed to replicate: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8494318/|date=July 2023}} Weak reputational cues such as eyespots may become unimportant if there are stronger cues present and may lose their effect with continued exposure unless reinforced with real reputational effects.<ref name=AEP1/> Public displays such as public weeping for dead celebrities and participation in demonstrations may be influenced by a desire to be seen as generous. People who know that they are publicly monitored sometimes even wastefully donate the money they know is not needed by the recipient because of reputational concerns.<ref name="AEP2">{{Cite book | last1=Iredal|first1=Wendy | last2=van Vugt|first2=Mark |chapter=Altruism as showing off: a signaling perspective on promoting green behavior and acts of kindness | editor1-last = Roberts | doi = 10.1093/acprof:oso/9780199586073.001.0001 | editor1-first = S. Craig | title = Applied Evolutionary Psychology | year = 2011 | publisher = Oxford University Press| isbn = 978-0-19-958607-3 }}</ref>

:Typically, women find altruistic men to be attractive partners. When women look for a long-term partner, altruism may be a trait they prefer as it may indicate that the prospective partner is also willing to [[Sharing|share]] resources with her and her children. Men perform charitable acts in the early stages of a romantic relationship or simply when in the presence of an attractive woman. While both sexes state that kindness is the most preferable trait in a partner, there is some evidence that men place less value on this than women and that women may not be more altruistic in the presence of an attractive man. Men may even avoid altruistic women in short-term relationships, which may be because they expect less success.<ref name=AEP1/><ref name=AEP2/>

:People may compete for the social benefit of a burnished reputation, which may cause [[competitive altruism]]. On the other hand, in some experiments, a proportion of people do not seem to care about reputation and do not help more, even if this is conspicuous. This may be due to reasons such as [[psychopathy]] or that they are so attractive that they need not be seen as altruistic. The reputational benefits of altruism occur in the future compared to the immediate costs of altruism. While humans and other organisms generally place less value on future costs/benefits as compared to those in the present, some have shorter time horizons than others, and these people tend to be less cooperative.<ref name=AEP1/>

:Explicit [[extrinsic]] rewards and punishments have sometimes been found to have a counterintuitively inverse effect on behaviors when compared to intrinsic rewards. This may be because such extrinsic incentives may replace (partially or in whole) intrinsic and reputational incentives, motivating the person to focus on obtaining the extrinsic rewards, which may make the thus-incentivized behaviors less desirable. People prefer altruism in others when it appears to be due to a personality characteristic rather than overt reputational concerns; simply pointing out that there are reputational benefits of action may reduce them. This may be used as a derogatory tactic against altruists ("you're just [[virtue signalling]]"), especially by those who are non-cooperators. A counterargument is that doing good due to reputational concerns is better than doing no good.<ref name=AEP1/>
* [[Group selection]]. It has controversially been argued by some evolutionary scientists such as [[David Sloan Wilson]] that natural selection can act at the level of non-kin groups to produce adaptations that benefit a non-kin group, even if these adaptations are detrimental at the individual level.<ref name="Wilson1983">{{cite journal |last1=Wilson |first1=D. S. |title=The group selection controversy: History and current status |journal=Annual Review of Ecology and Systematics |date=1983 |volume=14 |issue=1 |pages=159–187|doi=10.1146/annurev.es.14.110183.001111 |bibcode=1983AnRES..14..159W }}</ref> Thus, while altruistic persons may under some circumstances be outcompeted by less altruistic persons at the individual level, according to group selection theory, the opposite may occur at the group level where groups consisting of the more altruistic persons may outcompete groups consisting of the less altruistic persons. Such altruism may only extend to ingroup members while directing prejudice and antagonism against outgroup members (see also [[in-group favoritism]]). Many other evolutionary scientists have criticized group selection theory.<ref name="Leigh2010">{{cite journal |last1=Leigh Jr. |first1=E. G. |title=The group selection controversy |journal=Journal of Evolutionary Biology |date=2010 |volume=23 |issue=1 |pages=6–19|doi=10.1111/j.1420-9101.2009.01876.x |pmid=20002254 }}</ref>

[[File:Helping the homeless (cropped).jpg|right|thumb|Helping the [[Homelessness|homeless]] in New York City]]
Such explanations do not imply that humans consciously calculate how to increase their [[inclusive fitness]] when doing altruistic acts. Instead, evolution has shaped psychological mechanisms, such as emotions, that promote certain altruistic behaviors.<ref name=AEP1/>

The benefits for the altruist may be increased, and the costs reduced by being more altruistic towards certain groups. Research has found that people are more altruistic to kin than to no-kin, to friends than strangers, to those attractive than to those unattractive, to non-competitors than competitors, and to members in-groups than to members of out-groups.<ref name=AEP1/>

The study of altruism was the initial impetus behind [[George R. Price]]'s development of the [[Price equation]], a mathematical equation used to study genetic evolution. An interesting example of altruism is found in the cellular [[slime mould]]s, such as ''[[Dictyostelid|Dictyostelium]] mucoroides''. These protists live as individual [[amoeba]]e until starved, at which point they aggregate and form a multicellular fruiting body in which some cells sacrifice themselves to promote the survival of other cells in the fruiting body.<ref>{{cite journal |last1=Hudson |first1=Richard Ellis |last2=Aukema |first2=Juliann Eve |last3=Rispe |first3=Claude |last4=Roze |first4=Denis |title=Altruism, Cheating, and Anticheater Adaptations in Cellular Slime Molds |journal=The American Naturalist |date=July 2002 |volume=160 |issue=1 |pages=31–43 |doi=10.1086/340613 |pmid=18707497 |bibcode=2002ANat..160...31H |url=https://hal.inrae.fr/hal-02683365/file/2002_Hudson%20et%20al._Am%20Nat_1.pdf }}</ref>

Selective investment theory proposes that close social bonds, and associated emotional, cognitive, and neurohormonal mechanisms, evolved to facilitate long-term, high-cost altruism between those closely depending on one another for survival and reproductive success.<ref>{{cite journal |last1=Brown |first1=Stephanie L. |last2=Brown |first2=R. Michael |title=TARGET ARTICLE: Selective Investment Theory: Recasting the Functional Significance of Close Relationships |journal=Psychological Inquiry |date=January 2006 |volume=17 |issue=1 |pages=1–29 |doi=10.1207/s15327965pli1701_01 |s2cid=144718661 }}</ref>

Such cooperative behaviors have sometimes been seen as arguments for left-wing politics, for example, by the Russian [[Zoology|zoologist]] and [[Anarchism|anarchist]] [[Peter Kropotkin]] in his 1902 book ''[[Mutual Aid: A Factor of Evolution]]'' and moral philosopher [[Peter Singer]] in his book ''[[A Darwinian Left]]''.

===Neurobiology===
{{See also|Compassion}}
Jorge Moll and [[Jordan Grafman]], neuroscientists at the [[National Institutes of Health]] and LABS-D'Or Hospital Network, provided the first evidence for the neural bases of altruistic giving in normal healthy volunteers, using [[functional magnetic resonance imaging]]. In their research,<ref>{{cite journal | last1=Moll | first1=Jorge | last2=Krueger | first2=Frank | last3=Zahn | first3=Roland | last4=Pardini | first4=Matteo | last5=de Oliveira-Souza | first5=Ricardo | last6=Grafman | first6=Jordan | title=Human fronto–mesolimbic networks guide decisions about charitable donation | journal=Proceedings of the National Academy of Sciences | volume=103 | issue=42 | date=17 October 2006 | issn=0027-8424 | doi=10.1073/pnas.0604475103 | pages=15623–15628 | pmid=17030808 | pmc=1622872 | bibcode=2006PNAS..10315623M | doi-access=free }}</ref> they showed that both pure monetary rewards and charitable donations activated the [[Mesolimbic pathway|mesolimbic]] reward pathway, a primitive part of the brain that usually responds to food and sex. However, when volunteers generously placed the interests of others before their own by making charitable donations, another [[brain circuit]] was also selectively activated: the subgenual cortex/[[septal region]]. These structures are related to social attachment and bonding in other species. The experiment suggested that altruism is not a higher moral faculty overpowering innate selfish desires, but a fundamental, ingrained, and enjoyable trait in the brain.<ref name="brain">{{cite news
|url=https://www.washingtonpost.com/wp-dyn/content/article/2007/05/27/AR2007052701056.html
|title=If It Feels Good to Be Good, It Might Be Only Natural
|newspaper=The Washington Post
|date=28 May 2007
|first=Shankar
|last=Vedantam
|access-date=23 April 2010}}</ref> One brain region, the subgenual [[anterior cingulate cortex]]/[[basal forebrain]], contributes to learning altruistic behavior, especially in people with a propensity for [[empathy]].<ref name="PMID_27528669">{{multiref2
|1={{cite journal |last1 = Lockwood |first1 = Patricia L |last2 = Apps |first2 = Matthew A J |last3 = Valton |first3 = Vincent |last4 = Viding |first4 = Essi |last5 = Roiser |first5 = Jonathan P |year = 2016 |title = Neurocomputational mechanisms of prosocial learning and links to empathy. |journal = Proceedings of the National Academy of Sciences of the United States of America |quote = . fMRI revealed that activity in a posterior portion of the subgenual anterior cingulate cortex/basal forebrain (sgACC) drives learning only when we are acting in a prosocial context |pmid = 27528669 |doi=10.1073/pnas.1603198113 |volume=113 |issue = 35 |pages=9763–8|pmc = 5024617 |bibcode = 2016PNAS..113.9763L |doi-access = free}}
|2={{lay source |template=cite news |date=15 August 2016 |title=Finding the Brain's Generosity Center |url=https://neurosciencenews.com/generosity-empathy-neuroscience-4850/ |work=Neuroscience News}}
}}</ref><ref name="neurons">{{cite news |last=Svoboda |first=Elizabeth |date=5 September 2013 |title=Scientists Are Finding That We Are Hard-Wired for Giving |url=https://generosityresearch.nd.edu/news/hard-wired-for-giving/ |access-date=7 August 2017 |publisher=University of Notre Dame}}</ref><ref>{{Cite journal |last1=Shepelenko |first1=A. Yu. |last2=Kosonogov |first2=V. V. |date=1 February 2023 |title=Cerebral Support for Making Donation-Related Decision with Altruistic and Egoistic Motives |url=https://link.springer.com/article/10.1007/s11055-023-01413-9 |journal=Neuroscience and Behavioral Physiology |language=en |volume=53 |issue=2 |pages=242–246 |doi=10.1007/s11055-023-01413-9 |issn=1573-899X}}</ref>

Bill Harbaugh, a [[University of Oregon]] economist, in an fMRI scanner test conducted with his psychologist colleague Dr. Ulrich Mayr, reached the same conclusions as Jorge Moll and Jordan Grafman about giving to charity, although they were able to divide the study group into two groups: "egoists" and "altruists". One of their discoveries was that, though rarely, even some of the considered "egoists" sometimes gave more than expected because that would help others, leading to the conclusion that there are other factors in charity, such as a person's environment and values.<ref name="neurons"/>

A recent meta-analysis of fMRI studies conducted by Shawn Rhoads, Jo Cutler, and Abigail Marsh analyzed the results of prior studies of generosity in which participants could freely choose to give or not give resources to someone else.<ref>{{cite journal |last1=Rhoads |first1=Shawn A |last2=Cutler |first2=Jo |last3=Marsh |first3=Abigail A |title=A feature-based network analysis and fMRI meta-analysis reveal three distinct types of prosocial decisions |journal=Social Cognitive and Affective Neuroscience |date=30 December 2021 |volume=16 |issue=12 |pages=1214–1233 |doi=10.1093/scan/nsab079 |pmid=34160604 |pmc=8717062 }}</ref> The results of this study confirmed that altruism is supported by distinct mechanisms from giving motivated by reciprocity or by fairness. This study also confirmed that the right ventral striatum is recruited during altruistic giving, as well as the ventromedial prefrontal cortex, bilateral [[anterior cingulate cortex]], and bilateral anterior [[Insular cortex|insula]], which are regions previously implicated in [[empathy]].

[[Abigail Marsh]] has conducted studies of real-world altruists that have also identified an important role for the [[amygdala]] in human altruism. In real-world altruists, such as people who have donated kidneys to strangers, the amygdala is larger than in typical adults. Altruists' amygdalas are also more responsive than those of typical adults to the sight of others' distress, which is thought to reflect an empathic response to distress.<ref name=":0">{{Cite journal |last1=Marsh |first1=Abigail A. |last2=Stoycos |first2=Sarah A. |last3=Brethel-Haurwitz |first3=Kristin M. |last4=Robinson |first4=Paul |last5=VanMeter |first5=John W. |last6=Cardinale |first6=Elise M. |date=21 October 2014 |title=Neural and cognitive characteristics of extraordinary altruists |journal=Proceedings of the National Academy of Sciences|volume=111 |issue=42 |pages=15036–15041 |doi=10.1073/pnas.1408440111 |doi-access=free |issn=0027-8424 |pmc=4210306 |pmid=25225374|bibcode=2014PNAS..11115036M }}</ref><ref>{{Cite journal |last1=Brethel-Haurwitz |first1=Kristin M. |last2=O'Connell |first2=Katherine |last3=Cardinale |first3=Elise M. |last4=Stoianova |first4=Maria |last5=Stoycos |first5=Sarah A. |last6=Lozier |first6=Leah M. |last7=VanMeter |first7=John W. |last8=Marsh |first8=Abigail A. |date=25 October 2017 |title=Amygdala–midbrain connectivity indicates a role for the mammalian parental care system in human altruism |journal=Proceedings of the Royal Society B: Biological Sciences|volume=284 |issue=1865 |pages=20171731 |doi=10.1098/rspb.2017.1731 |issn=0962-8452 |pmc=5666102 |pmid=29070724}}</ref> This structure may also be involved in altruistic choices due to its role in encoding the value of outcomes for others.<ref>{{cite journal |last1=Rhoads |first1=Shawn A |last2=O'Connell |first2=Katherine |last3=Berluti |first3=Kathryn |last4=Ploe |first4=Montana L |last5=Elizabeth |first5=Hannah S |last6=Amormino |first6=Paige |last7=Li |first7=Joanna L |last8=Dutton |first8=Mary Ann |last9=VanMeter |first9=Ashley Skye |last10=Marsh |first10=Abigail A |title=Neural responses underlying extraordinary altruists' generosity for socially distant others |journal=PNAS Nexus |date=3 July 2023 |volume=2 |issue=7 |pages=pgad199 |doi=10.1093/pnasnexus/pgad199 |pmc=10321390 |pmid=37416875 }}</ref> This is consistent with the findings of research in non-human animals, which has identified neurons within the amygdala that specifically encode the value of others' outcomes, activity in which appears to drive altruistic choices in monkeys.<ref>{{Cite journal |last1=Dal Monte |first1=Olga |last2=Chu |first2=Cheng C. J. |last3=Fagan |first3=Nicholas A. |last4=Chang |first4=Steve W. C. |date=April 2020 |title=Specialized medial prefrontal–amygdala coordination in other-regarding decision preference |journal=Nature Neuroscience|volume=23 |issue=4 |pages=565–574 |doi=10.1038/s41593-020-0593-y |pmid=32094970 |pmc=7131896 |issn=1546-1726|hdl=2318/1730693 |hdl-access=free }}</ref><ref>{{cite journal |last1=Putnam |first1=Philip T. |last2=Chu |first2=Cheng-Chi J. |last3=Fagan |first3=Nicholas A. |last4=Dal Monte |first4=Olga |last5=Chang |first5=Steve W.C. |title=Dissociation of vicarious and experienced rewards by coupling frequency within the same neural pathway |journal=Neuron |date=August 2023 |volume=111 |issue=16 |pages=2513–2522.e4 |doi=10.1016/j.neuron.2023.05.020 |pmid=37348507 |pmc=10527039 }}</ref>

===Psychology===
The ''International Encyclopedia of the Social Sciences'' defines ''psychological altruism'' as "a motivational state to increase another's welfare". Psychological altruism is contrasted with ''psychological egoism'', which refers to the motivation to increase one's welfare.<ref name="encyclopedia">{{cite encyclopedia|article=Altruism|encyclopedia = International Encyclopedia of the Social Sciences|editor-first= William A. Jr. |editor-last = Darity|edition= 2nd |volume = 1|location = Detroit|publisher = Macmillan Reference USA|date= 2008|pages = 87–88}}</ref> In keeping with this, research in real-world altruists, including altruistic kidney donors, bone marrow donors, humanitarian aid workers, and [[hero]]ic rescuers findings that these altruists are primarily distinguished from other adults by unselfish traits and decision-making patterns. This suggests that human altruism reflects genuinely high valuation of others' outcomes.<ref name=":1">{{Cite journal |last1=Rhoads |first1=Shawn A. |last2=Vekaria |first2=Kruti M. |last3=O’Connell |first3=Katherine |last4=Elizabeth |first4=Hannah S. |last5=Rand |first5=David G. |last6=Kozak Williams |first6=Megan N. |last7=Marsh |first7=Abigail A. |date=31 March 2023 |title=Unselfish traits and social decision-making patterns characterize six populations of real-world extraordinary altruists |journal=Nature Communications|volume=14 |issue=1 |pages=1807 |doi=10.1038/s41467-023-37283-5 |issn=2041-1723|doi-access=free |pmid=37002205 |pmc=10066349 }}</ref>

There has been some debate on whether humans are capable of psychological altruism.<ref name="batson3">{{cite book|last=Batson|first=C.|year=2011|title=Altruism in humans|location=New York, N.Y. U.S.|publisher=Oxford University Press}}</ref> Some definitions specify a self-sacrificial nature to altruism and a lack of external rewards for altruistic behaviors.<ref name="prosocial">{{cite book|last=Batson|first= C. Daniel |date=2012|chapter = A history of prosocial behavior research |editor1-first = Arie W.|editor1-last= Kruglanski|editor2-link=Wolfgang Stroebe|editor2-first=Wolfgang|editor2-last = Stroebe|title = Handbook of the history of social psychology |pages = 243–264|location= New York, NY |publisher = Psychology Press|isbn =978-1-84872-868-4 |chapter-url = https://books.google.com/books?id=MOlUSV2koMcC&pg=PA242}}</ref> However, because altruism ultimately benefits the self in many cases, the selflessness of altruistic acts is difficult to prove. The [[social exchange theory]] postulates that altruism only exists when the benefits outweigh the costs to the self.<ref name="noaltruism">{{cite journal |last1=Maner |first1=Jon K. |last2=Luce |first2=Carol L. |last3=Neuberg |first3=Steven L. |last4=Cialdini |first4=Robert B. |last5=Brown |first5=Stephanie |last6=Sagarin |first6=Brad J. |title=The Effects of Perspective Taking on Motivations for Helping: Still No Evidence for Altruism |journal=Personality and Social Psychology Bulletin |date=November 2002 |volume=28 |issue=11 |pages=1601–1610 |doi=10.1177/014616702237586 }}</ref>

[[Daniel Batson]], a psychologist, examined this question and argued against the social exchange theory. He identified four significant motives: to ultimately benefit the self (egoism), to ultimately benefit the other person (altruism), to benefit a group (collectivism), or to uphold a moral principle ([[principlism]]). Altruism that ultimately serves selfish gains is thus differentiated from selfless altruism, but the general conclusion has been that [[empathy]]-induced altruism can be genuinely selfless.<ref name="baston2">{{cite book|last1=Batson|first1= C. Daniel|last2= Ahmad|first2= Nadia|last3= Stocks|first3= E. L. |date = 2011|chapter = Four forms of prosocial motivation: Egoism, altruism, collectivism, and principlism|editor-first = David|editor-last =Dunning|title = Social motivation |pages = 103–126|location= New York, NY |publisher = Psychology Press|chapter-url = https://books.google.com/books?id=gOB4AgAAQBAJ&pg=PA103|isbn = 978-1-136-84720-2}}</ref> The ''[[empathy-altruism]] hypothesis'' states that psychological altruism exists and is evoked by the empathic desire to help someone suffering. Feelings of empathic concern are contrasted with personal distress, which compels people to reduce their unpleasant emotions and increase their positive ones by helping someone in need. Empathy is thus not selfless since altruism works either as a way to avoid those negative, unpleasant feelings and have positive, pleasant feelings when triggered by others' need for help or as a way to gain social reward or avoid social punishment by helping. People with empathic concern help others in distress even when exposure to the situation could be easily avoided, whereas those lacking in empathic concern avoid allowing it unless it is difficult or impossible to avoid exposure to another's suffering.<ref name="encyclopedia"/>

Helping behavior is seen in humans from about two years old when a toddler can understand subtle emotional cues.<ref>{{cite journal|last1=Svetlova|first1=M.|last2=Nichols|first2=S. R. |last3= Brownell|first3=C. A.|year=2010|title=Toddlers prosocial behavior: From instrumental to empathic to altruistic helping|journal=Child Development |volume=81|issue=6|pages=1814–1827|doi=10.1111/j.1467-8624.2010.01512.x|pmid=21077866|pmc=3088085}}</ref>

[[File:Peace Corps Volunteer swearing in Cambodia, 2007.jpg|thumb|[[Peace Corps]] trainees swearing in as volunteers in [[Cambodia]], 4 April 2007]]
In psychological research on altruism, studies often observe altruism as demonstrated through [[prosocial behavior]]s such as [[Helping behavior|helping]], comforting, [[sharing]], cooperation, [[philanthropy]], and [[community service]].<ref name="prosocial"/> People are most likely to help if they recognize that a person is in need and feel personal responsibility for reducing the person's distress. The number of bystanders witnessing pain or suffering affects the likelihood of helping (the ''[[Bystander effect]]''). More significant numbers of bystanders decrease individual feelings of responsibility.<ref name="encyclopedia"/><ref>{{cite journal | last1 = Hudson | first1 = James M. | last2 = Bruckman | first2 = Amy S. | year = 2004 | title = The Bystander Effect: A Lens for Understanding Patterns of Participation | journal = Journal of the Learning Sciences | volume = 13 | issue = 2| pages = 165–195 | doi = 10.1207/s15327809jls1302_2 | citeseerx = 10.1.1.72.4881 | s2cid = 16442298 }}</ref> However, a witness with a high level of empathic concern is likely to assume personal responsibility entirely regardless of the number of bystanders.<ref name="encyclopedia"/>

Many studies have observed the effects of [[volunteering|volunteerism]] (as a form of altruism) on happiness and health and have consistently found that those who exhibit volunteerism also have better current and future health and well-being.<ref name="volunteer1">{{cite journal|last1=Musick|first1=M. A.|last2=Wilson|first2=J.|year=2003|title=Volunteering and depression: The role of psychological and social resources in different age groups|journal=Social Science & Medicine|volume=56|issue=2|pages=259–269|doi=10.1016/S0277-9536(02)00025-4|pmid=12473312}}</ref><ref>{{cite journal | last1 = Koenig | first1 = L. B. | last2 = McGue | first2 = M. | last3 = Krueger | first3 = R. F. | last4 = Bouchard | year = 2007 | title = Religiousness, antisocial behavior, and altruism: Genetic and environmental mediation | journal = Journal of Personality | volume = 75 | issue = 2| pages = 265–290 | doi = 10.1111/j.1467-6494.2007.00439.x | pmid = 17359239 }}</ref> In a study of older adults, those who volunteered had higher life satisfaction and will to live, and less [[Depression (mood)|depression]], [[anxiety (mood)|anxiety]], and [[somatization]].<ref>{{cite journal|last1=Hunter|first1=K. I.|last2=Hunter|first2=M. W.|year=1980|title=Psychosocial differences between elderly volunteers and non-volunteers|journal=The International Journal of Aging & Human Development|volume=12|issue=3|pages=205–213|doi=10.2190/0H6V-QPPP-7JK4-LR38|pmid=7216525|s2cid=42991434}}</ref> Volunteerism and helping behavior have not only been shown to improve mental health but physical health and longevity as well, attributable to the activity and social integration it encourages.<ref name="volunteer1"/><ref>{{multiref2
|1={{cite journal | last1 = Kayloe | first1 = J. C. | last2 = Krause | first2 = M. | year = 1985 | title = RARE FIND: or The value of volunteerism | journal = Psychosocial Rehabilitation Journal | volume = 8 | issue = 4| pages = 49–56 | doi=10.1037/h0099659}}
|2={{cite journal|last1=Brown|first1=S. L.|last2=Brown|first2=R.|last3=House|first3=J. S.|last4=Smith|first4=D. M.|year=2008|title=Coping with spousal loss: Potential buffering effects of self-reported helping behavior|journal=Personality and Social Psychology Bulletin|volume=34|issue=6|pages=849–861|doi=10.1177/0146167208314972|pmid=18344495|s2cid=42983453}}
}}</ref><ref name="volunteer5">{{cite journal|last1=Post|first1=S. G.|year=2005|title=Altruism, Happiness, and Health: It's Good to Be Good|journal=International Journal of Behavioral Medicine|volume=12|issue=2|pages=66–77|doi=10.1207/s15327558ijbm1202_4|pmid=15901215|citeseerx=10.1.1.485.8406|s2cid=12544814}}</ref> One study examined the physical health of mothers who volunteered over 30 years and found that 52% of those who did not belong to a volunteer organization experienced a major illness while only 36% of those who did volunteer experienced one.<ref>{{cite journal |last1=Moen |first1=P. |last2=Dempster-Mcclain |first2=D. |last3=Williams |first3=R. M. |s2cid=4828775 |year=1992|title=Successful aging: A life-course perspective on women's multiple roles and health|journal=American Journal of Sociology|volume=97|issue=6|pages=1612–1638|doi=10.1086/229941}}</ref> A study on adults aged 55 and older found that during the four-year study period, people who volunteered for two or more organizations had a 63% lower likelihood of dying. After controlling for prior health status, it was determined that volunteerism accounted for a 44% reduction in mortality.<ref>{{cite journal|last1=Oman|first1=D.|last2=Thoresen|first2=C. E.|last3=McMahon|first3=K.|year=1999|title=Volunteerism and mortality among the community-dwelling elderly|journal=Journal of Health Psychology|volume=4|issue=3|pages=301–316|doi=10.1177/135910539900400301|pmid=22021599|doi-access=free}}</ref> Merely being aware of kindness in oneself and others is also associated with greater well-being. A study that asked participants to count each act of kindness they performed for one week significantly enhanced their subjective happiness. Happier people are kinder and more grateful, kinder people are happier and more grateful and more grateful people are happier and kinder, the study suggests.<ref name="countingkindness">{{cite journal|last1=Otake|first1=K.|last2=Shimai|first2=S.|last3=Tanaka-Matsumi|first3=J.|last4=Otsui|first4=K.|last5=Fredrickson|first5=B. L.|year=2006|title=Happy people become happier through kindness: A counting kindnesses intervention|journal=Journal of Happiness Studies|volume=7|issue=3|pages=361–375|doi=10.1007/s10902-005-3650-z|pmid=17356687|pmc=1820947}}</ref>

While research supports the idea that altruistic acts bring about happiness, it has also been found to work in the opposite direction—that happier people are also kinder. The relationship between altruistic behavior and happiness is bidirectional. Studies found that [[generosity]] increases linearly from sad to happy affective states.<ref name="moodandgenerosity">{{cite journal|last1=Underwood|first1=B.|last2=Froming|first2=W. J.|last3=Moore|first3=B. S.|year=1977|title=Mood, attention, and altruism: A search for mediating variables|journal=Developmental Psychology|volume=13|issue=5|pages=541–542|doi=10.1037/0012-1649.13.5.541}}</ref>

Feeling over-taxed by the needs of others has negative effects on health and happiness.<ref name="volunteer5"/> For example, one study on volunteerism found that feeling overwhelmed by others' demands had an even stronger negative effect on mental health than helping had a positive one (although positive effects were still significant).<ref name="overwhelmed">{{cite journal|last1=Schwartz|first1=C.|last2=Meisenhelder|first2=J.|last3=Ma|first3=Y.|last4=Reed|first4=G.|year=2003|title=Altruistic Social Interest Behaviors Are Associated With Better Mental Health|journal=Psychosomatic Medicine|volume=65|issue=5|pages=778–785|doi=10.1097/01.PSY.0000079378.39062.D4|pmid=14508020|citeseerx=10.1.1.529.7780|s2cid=20644442}}</ref>

Older humans were found to have higher altruism.<ref name="w730">{{cite journal | last1=Sparrow | first1=Erika P. | last2=Swirsky | first2=Liyana T. | last3=Kudus | first3=Farrah | last4=Spaniol | first4=Julia | title=Aging and altruism: A meta-analysis. | journal=Psychology and Aging | publisher=American Psychological Association (APA) | volume=36 | issue=1 | year=2021 | issn=1939-1498 | doi=10.1037/pag0000447 | pages=49–56| pmid=33705185 }}</ref>

===Genetics and environment===
Both genetics and environment have been implicated in influencing pro-social or altruistic behavior.<ref>{{cite book |doi=10.1093/acprof:oso/9780199964772.003.0001 |title=Prosocial Development |date=2014 |publisher=Oxford University Press |isbn=978-0-19-996477-2 |editor-last1=Padilla-Walker |editor-last2=Carlo |editor-first1=Laura M. |editor-first2=Gustavo |chapter=1 The Study of Prosocial Behavior: Past, Present, and Future |pages=3–16 }}</ref> Candidate genes include OXTR ([[gene polymorphism|polymorphism]]s in the [[oxytocin receptor]]),<ref>{{cite journal |last1=Singer |first1=Tania |last2=Snozzi |first2=Romana |last3=Bird |first3=Geoffrey |last4=Petrovic |first4=Predrag |last5=Silani |first5=Giorgia |last6=Heinrichs |first6=Markus |last7=Dolan |first7=Raymond J. |title=Effects of oxytocin and prosocial behavior on brain responses to direct and vicariously experienced pain |journal=Emotion |date=December 2008 |volume=8 |issue=6 |pages=781–791 |doi=10.1037/a0014195 |pmid=19102589 |pmc=2672051 }}</ref><ref>{{cite journal |last1=Israel |first1=Salomon |last2=Weisel |first2=Ori |last3=Ebstein |first3=Richard P. |last4=Bornstein |first4=Gary |title=Oxytocin, but not vasopressin, increases both parochial and universal altruism |journal=Psychoneuroendocrinology |date=August 2012 |volume=37 |issue=8 |pages=1341–1344 |doi=10.1016/j.psyneuen.2012.02.001 |pmid=22377540 }}</ref><ref>{{cite journal |last1=Barraza |first1=Jorge A. |last2=McCullough |first2=Michael E. |last3=Ahmadi |first3=Sheila |last4=Zak |first4=Paul J. |title=Oxytocin infusion increases charitable donations regardless of monetary resources |journal=Hormones and Behavior |date=July 2011 |volume=60 |issue=2 |pages=148–151 |doi=10.1016/j.yhbeh.2011.04.008 |pmid=21596046 }}</ref> [[CD38]], [[COMT]], [[DRD4]], [[DRD5]], [[IGF2]], [[AVPR1A]]<ref>{{cite journal | doi=10.1371/journal.pone.0025274 | doi-access=free | title=AVPR1A Variant Associated with Preschoolers' Lower Altruistic Behavior | date=2011 | last1=Avinun | first1=Reut | last2=Israel | first2=Salomon | last3=Shalev | first3=Idan | last4=Gritsenko | first4=Inga | last5=Bornstein | first5=Gary | last6=Ebstein | first6=Richard P. | last7=Knafo | first7=Ariel | journal=PLOS ONE | volume=6 | issue=9 | pages=e25274 | pmid=21980412 | pmc=3182215 | bibcode=2011PLoSO...625274A }}</ref> and [[GABRB2]].<ref>{{cite journal| pmc=3871336 | pmid=24132092 | doi=10.1098/rsbl.2013.0395 | volume=9 | issue=6 | title=Genes underlying altruism | year=2013 | journal=Biol Lett | page=20130395 | last1 = Thompson | first1 = GJ | last2 = Hurd | first2 = PL | last3 = Crespi | first3 = BJ}}</ref> It is theorized that some of these genes influence altruistic behavior by modulating levels of neurotransmitters such as [[serotonin]] and [[dopamine]].

According to [[Christopher Boehm]], altruistic behaviour evolved as a way of surviving within a group.<ref>{{cite journal | url=https://psycnet.apa.org/record/2011-29744-000 | title=Moral origins: The evolution of virtue, altruism, and shame | journal=Apa Psycnet | date=2012 | last1=Christopher | first1=Boehm }}</ref>

===Sociology===
{{See also|Public sociology}}
"Sociologists have long been concerned with how to build the good society".<ref name="ASA-AMSS">{{Cite web|url=http://www.asanet.org/sections/altruism.cfm|archive-url=https://web.archive.org/web/20120503051933/http://asanet.org/sections/altruism.cfm|url-status=dead|publisher=American Sociological Association|title=Altruism, Morality, and Social Solidarity|archive-date=3 May 2012}}</ref> The structure of our societies and how individuals come to exhibit charitable, philanthropic, and other pro-social, altruistic actions for the [[common good]] is a commonly researched topic within the field. The American Sociology Association (ASA) acknowledges [[public sociology]] saying, "The intrinsic scientific, policy, and public relevance of this field of investigation in helping to construct 'good societies' is unquestionable".<ref name="ASA-AMSS" /> This type of sociology seeks contributions that aid popular and theoretical understandings of what motivates altruism and how it is organized, and promotes an altruistic focus in order to benefit the world and people it studies.

How altruism is framed, organized, carried out, and what motivates it at the group level is an area of focus that sociologists investigate in order to contribute back to the groups it studies and "build the good society". The motivation of altruism is also the focus of study; for example, one study links the occurrence of moral outrage to altruistic compensation of victims.<ref>{{cite journal|last1=Thulin|first1=E.W.|author-link2=Cristina Bicchieri|last2=Bicchieri|first2=C.|title=I'm so angry I could help you: Moral outrage as a driver of victim compensation|journal=Social Philosophy & Policy|year=2016|volume=32|issue=2 |pages=146–160|doi=10.1017/S0265052516000145 |s2cid=148548711 }}</ref> Studies show that [[generosity]] in laboratory and in online experiments is contagious – people imitate the generosity they observe in others.<ref>{{multiref2
|1={{cite book |last1=Tsvetkova |first1=Milena |last2=Macy |first2=Michael |chapter=The Contagion of Prosocial Behavior and the Emergence of Voluntary-Contribution Communities |title=Social Phenomena: From Data Analysis to Models |date=2015 |pages=117–134 |doi=10.1007/978-3-319-14011-7_7 |isbn=978-3-319-14010-0 |publisher=Springer International Publishing}}
|2={{cite journal |last1=Tagiew |first1=Rustam |last2=Ignatov |first2=Dmitry |title=Gift Ratios in Laboratory Experiments |journal=CEUR Workshop Proceedings |date=2016 |volume=1627 |pages=82–93 |url=http://ceur-ws.org/Vol-1627/paper7.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://ceur-ws.org/Vol-1627/paper7.pdf |archive-date=9 October 2022 |url-status=live}}
}}</ref>