Working with captive primates, de Waal and Johanowicz created a mixed-sex social group of juvenile macaques, combining rhesus and stump tails together. Remarkably, instead of the rhesus macaques bullying the stump tails, over the course of a few months the rhesus males adopted the stump tails’ social style, eventually even matching the stump tails’ high rates of reconciliatory behavior. It so happens, moreover, that stump tails and rhesus macaques use different gestures when reconciling. The rhesus macaques in the study did not start using the stump tails’ reconciliatory gestures, but rather increased the incidence of their own species-typical gestures. In other words, they were not merely imitating the stump tails’ behavior; they were incorporating the concept of frequent reconciliation into their own social practices. Finally, when the newly warm-and-fuzzy rhesus macaques were returned to a larger, all-rhesus group, their new behavioral style persisted.
An amazing way of looking at this is persistence of social qualities, regardless of the biological vector involved. On the other hand, such social qualities do not appear to be viral by any means: "This is nothing short of extraordinary. But it brings up one further question: When those rhesus macaques were transferred back into the all-rhesus world, did they spread their insights and behaviors to the others? Alas, they did not—at least not within the relatively short time they were studied. For that, we need to move on to a final case."