TY - JOUR
T1 - The amplifying role of need in giving decisions
AU - Danvers, Alexander F.
AU - Hackman, Joseph V.
AU - Hruschka, Daniel
N1 - Funding Information:
DJH acknowledges support from the National Science Foundation grant BCS-1150813 , jointly funded by the Programs in Cultural Anthropology, Social Psychology Program and Decision, Risk, and Management Sciences .
Funding Information:
AFD acknowledges support from a John Templeton Foundation grant for a postdoctoral fellowship at the Institute for the Study of Human Flourishing at the University of Oklahoma.
Publisher Copyright:
© 2018
PY - 2019/3
Y1 - 2019/3
N2 - Hamilton's rule predicts that altruism should depend on costs incurred and benefits provided, but these depend on the relative needs of the donor and recipient. Rewriting Hamilton's rule to account for relative need suggests an amplifying effect of need on relatedness, but not necessarily other relationship qualities. In a reanalysis of three studies of social discounting and a new replication, we find that relative need amplifies the effects of relatedness on giving in two samples of U.S. adults recruited online, but not U.S. undergraduates or Indian adults recruited online. Among U.S. online participants, the effect of genetic kinship was greater when the partner was perceived to be in higher need than when in lower need. In the other samples, relatedness and greater partner need were associated with greater giving, but the effect of relatedness on giving was not significantly amplified by need. Need never amplified the effect of social closeness on giving, although it did diminish the effect of closeness in U.S. undergraduates, likely reflecting a ceiling effect. These results confirm predictions from a modification of Hamilton's rule in a sample of U.S. adults, but raise important questions about why they hold in some samples but not others. They also illustrate the importance of understanding how contextual factors, such as relative need, can moderate the importance of common variables used in evolutionary cost-benefit analyses.
AB - Hamilton's rule predicts that altruism should depend on costs incurred and benefits provided, but these depend on the relative needs of the donor and recipient. Rewriting Hamilton's rule to account for relative need suggests an amplifying effect of need on relatedness, but not necessarily other relationship qualities. In a reanalysis of three studies of social discounting and a new replication, we find that relative need amplifies the effects of relatedness on giving in two samples of U.S. adults recruited online, but not U.S. undergraduates or Indian adults recruited online. Among U.S. online participants, the effect of genetic kinship was greater when the partner was perceived to be in higher need than when in lower need. In the other samples, relatedness and greater partner need were associated with greater giving, but the effect of relatedness on giving was not significantly amplified by need. Need never amplified the effect of social closeness on giving, although it did diminish the effect of closeness in U.S. undergraduates, likely reflecting a ceiling effect. These results confirm predictions from a modification of Hamilton's rule in a sample of U.S. adults, but raise important questions about why they hold in some samples but not others. They also illustrate the importance of understanding how contextual factors, such as relative need, can moderate the importance of common variables used in evolutionary cost-benefit analyses.
KW - Giving
KW - Kin selection
KW - Need-based giving
KW - Social discounting
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U2 - 10.1016/j.evolhumbehav.2018.11.002
DO - 10.1016/j.evolhumbehav.2018.11.002
M3 - Article
AN - SCOPUS:85056811701
SN - 1090-5138
VL - 40
SP - 188
EP - 193
JO - Evolution and Human Behavior
JF - Evolution and Human Behavior
IS - 2
ER -