We suggest that competitive altruism in chimps does not emerge just as a by-product of them trying to increase over previous losses. Chimps might consider how others’ affect their outcomes and engage in strategies to maximize their chances of being selected as cooperative partners.

Under specific conditions, chimps outcompete first proposers in triadic consecutive trials before the responder could choose which offer to accept.
They did so by offering more than what was expected if they acted randomly or offered the smallest possible amount.

We explored whether chimps engaged in competitive altruism in a triadic UG where two proposers could send offers to a responder who could only accept one offer.
They could make offers simultaneously or consecutively. We ran dyadic control trials where only one ape could offer.