Vervet monkeys have three confirmed predators: leopards, eagles, and pythons.
With that many enemies, they are always on guard for danger, and when they perceive a threat, they give an alarm that is specific to the threat.
If it’s an eagle, they give an eagle alarm. They take up the cry, and run for cover under the trees.
If it’s a python that’s threatening them, the vervets do the opposite. They climb up into the tree repeating a different call — snake! snake! snake!
If they spot a leopard, they make a still different cry, and leap into the tree, only this time they go out onto the narrowest, most lightweight branches — the perfect place to be when being pursued by a 200 pound cat that wants to eat you.
Robert Seyfarth and Dorothy Cheney of the University of Pennsylvania have even stimulated these responses in vervets using alarm call recordings.
I think it’s pretty clear that African Vervets have a language. Their vocabulary may be limited, but their cries perform the same task that some of our presentations are meant to perform.
They watch out for challenges, dangers, and instability in their communities. They get their listeners to pay attention, solve a narrow range of problems, and DO something specific.