In a Study Done with Vervets, Researchers Found That

In a study done with vervets, researchers found that

A) genetic relatedness is necessary for contingent reciprocity to occur.
B) they responded to recruitment calls from other monkeys after receiving grooming bouts from them.
C) contingent reciprocity can evolve as confederates react appropriately to the presence and absence of reciprocity.
D) agemates were more likely to be reciprocal.