Science - USA (2020-09-04)

conducive to generalized prosociality. In a
series of cross-cultural studies, Henrich and
his colleagues uncovered less prosocial behav-
ior in small-scale societies based on kinship
networks than in market-integrated socie-
ties in which strangers regularly engage in
mutually beneficial transactions. In their
words,“The more frequently people experi-
ence market transactions, the more they will
also experience abstract sharing principles
concerning behaviors toward strangers”[( 6 ),
p. 76)]. Market integration not only fosters
prosociality toward unknown others; it can
also shift boundaries to include noncoeth-
nics. In a nationwide field experiment in Italy,
market integration explained variation in
prosocial behavior toward both natives and
immigrants ( 7 ). Similar effects are imputed to
globalization, understood as greater world-
wide connectedness ( 49 ).
Workplaces, more than homes or neighbor-
hoods, may be crucial for fostering the type of
prosociality that holds modern societies to-
gether. Minorities’and immigrants’positions
in the productive system and their prospects
for social mobility—including employment op-
portunities in complementary sectors, and
a legal regime that protects their rights as
workers—are therefore important not only
for their own material success but for society
as a whole. The economic integration of mi-
norities and immigrants also determines the
extent to which they come to identify with
mainstream society ( 50 ).
Most economic exchanges—for example,
hiring someone or renting an apartment from
them—are strategic in nature, in the sense
that a person’s behavior is affected by their
expectations of the alter.Thesetypesofinter-
action entail risk and uncertainty because
people have to overcome difficulties related
to coordination, lack of information, and mis-
trust. Cooperative and prosocial behavior in
these settings may still be affected by in-group
favoritism but are also based on consider-
ations that go beyond whether an ego likes or
dislikes the alter, to encompass the alter’s
trustworthiness, competence, and reputation
( 40 ). This calls for a deeper understanding
of intergroup dynamics, and the institutional
arrangements, that favor prosocial outcomes
in the context of strategic interactions. Some
field experimental work has made progress in
this direction; for example, in a study of pub-
licgoodsprovisionindiverseUgandanneigh-
borhoods, Habyarimana and colleagues used
behavioral games to disentangle the various
motives and mechanisms that bring about
collective action in multiethnic contexts ( 2 ).
Although they did not find evidence of ethnic
favoritism, they found that the reciprocity
norms and sanctioning opportunities that fa-
cilitate cooperation in risky interactions are
stronger among coethnics than noncoethnics.

Market integration enhances opportuni-

ties for productive interactions across group

boundaries. Additionally, the strategic nature

of economic exchanges elicits decision-making

processes that go beyond in-group favoritism,

therefore providing new venues for institu-

tional intervention.

Conclusion

We can approach ethnic diversity through the

lens of lost homogeneity. From this perspec-

tive, we understand that members of the white

majority tend to react negatively to the growth

of immigrants and minorities in their com-

munities. However, it would be premature to

conclude that diversity ordiversificationper

se are to blame for declining levels of trust and

cooperation. In the Western European and

North American context, diversity is synon-

ymous with immigrant and minority share

and economic disadvantage, and statistical

attempts at disentangling their effects will

not get us very far.

Beyond questioning the effects of ethnic di-

versity, scholars should develop a theory of

social cohesion in multiethnic societies that

considers intergroup dynamics, social cleav-

ages, and asymmetries in resources and power.

Crucial to this effort is understanding the con-

ditions under which prosocial behavior extends

beyond close-knit networks and the safe con-

fines of the in-group. Here, we have high-

lighted two features of modern societies, social

differentiation and economic interdependence,

that set the stage for generalized prosociality

to develop. We argue that, in contrast with the

in-group solidarity that glues homogeneous

communities together, prosociality in heter-

ogeneous societies likely derives from posi-

tive experiences in the context of strategic

interactions. Further research is needed on

the mechanisms and institutional arrange-

ments that foster this higher-level form of

cooperation.

The experience of immigrants and minori-

ties is instructive regarding the conditions and

institutions that facilitate integration and mo-

bility in Western societies. Of primary im-

portance are employment opportunities in

mainstream labor markets, especially under

conditions of economicexpansion, along with

legal and political inclusion. Regrettably, it

is precisely these conditions that are in short

supply in a historical moment characterized

bytheriseofright-wingmovements,aneco-

nomic recession induced by a global pandemic,

and long-standing institutional practices,

such as those of law enforcement, that deepen

the divides between ethnoracial groups. Wheth-

er societal adaptation to diversity moves toward

integration or social division depends as much

on microinteractions on the ground as on the

economic and political institutions that gov-

ern these processes.

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ACKNOWLEDGMENTS

The authors thank B. Park for work on the figures and the referees for

helpful comments.Funding:D.B. acknowledges support from the

European Research Council (639284) and M.A. from the National

Science Foundation (1845177).Author contributions:D.B. and M.A.

wrote the Review.Competing interests:The authors have no

competing interests.Data and materials availability:Data for Fig. 1A

came from the United Nations Population Division and are available at

https://migrationdataportal.org/?i=stock_abs_&t=2015. Data for Fig.

1B were collected by L. Drazanova and posted ( 51 ).

10.1126/science.abb2432

Baldassarriet al.,Science 369 , 1183–1187 (2020) 4 September 2020 5of5

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