Barbados green monkeys (Chlorocebus sabaeus) recognize ancestral alarm calls after 350 years of isolation

Vervet monkeys (Chlorocebus pygerythrus) produce alarm calls and anti-predator behaviors that are specific to a threatening predator's mode of attack. Upon hearing a leopard alarm, the monkeys will run up trees where they are relatively safe. In contrast, eagle alarms prompt the monkeys to run under bushes and snake alarms stimulate bipedal standing. Early researchers proposed that the meaning of each alarm call is conveyed by observational learning. If this true then absence of the predator that elicits the alarm call may lead to alteration or decay of the alarm's meaning since there is no longer opportunity for observational learning to occur. The present study tested this hypothesis by presenting alarm calls to a closely related species of monkeys (Chlorocebus sabaeus) that have been isolated from their ancestral predators for more than 350 years. The monkeys ran up trees in response to a leopard alarm, but not when the same alarm was played backwards and not in response to a snake alarm. Snake alarms failed to reliably elicit bipedal standing. These results suggest that the leopard alarm call conveys the same information to Barbados green monkeys as West African green monkeys despite generations of isolation from leopards.