They received offers from other human partners and from a computer partner.
Responders refused unfair offers from human partners at a significantly higher rate than those from a computer partner.
The experiment also suggested that altruistic punishment is associated with negative emotions that are generated in unfair situations by the anterior insula of the brain. This behavior appears, however, to occur mostly between relatives.
They maintain that helpers may receive more direct, and less indirect, gains from assisting others than is commonly reported.
Furthermore, they insist that cooperation may not solely be an interaction between two individuals but may be part of the broader goal of unifying populations.
It was found that this "delayed dispersal," while it involved helping other wolves rear their offspring, extended male wolves’ life spans.
These findings suggest that kin selection may not only benefit an individual in the long-term in terms of increased fitness but in the short-term as well through enhanced chance of survival.
One reason may be that if the prisoner's dilemma situation is repeated (the iterated prisoner's dilemma), it allows non-cooperation to be punished more, and cooperation to be rewarded more, than the single-shot version of the problem would suggest.
It has been suggested that this is one reason for the evolution of complex emotions in higher life forms.
Together, the essays confront evidence that households engaged in agriculture do not behave as unitary decision makers but are instead sites of conflict and hierarchy.
As dynamics of intrahousehold differences in capabilities, constraints, and control, bound individual agency, they define gender specific strategies.
contention that helpers obtain both immediate and long-term gains from cooperative breeding.
Researchers evaluated the consequences of red wolves’ decisions to stay with their packs for extended periods of time after birth.
Individual action on behalf of a larger system may be coerced (forced), voluntary (freely chosen), or even unintentional, and consequently individuals and groups might act in concert even though they have almost nothing in common as regards interests or goals.