Final answer:
Vervet monkey alarm calls are distinct per predator type, demonstrate learning, and are symbolic, indicative of a basic form of language that affects natural selection.
Step-by-step explanation:
In vervet monkeys, alarm calls have several characteristics. Firstly, these alarm calls demonstrate some evidence of learning being important as there can be a cultural transmission of the specific calls within groups. Secondly, the calls are quite distinct depending on the type of predator identified, with specific calls for predators like leopards, eagles, and snakes. Lastly, these calls contain information that is considered to be symbolic because they convey specific information about the type of threat to other members of the group.
For example, when vervet monkeys hear a "leopard" call, they quickly ascend to higher branches, since leopards are a terrestrial threat. When they hear an "eagle" call, the monkeys seek shelter in dense bushes or trees to hide from this aerial predator. In response to a "snake" call, vervet monkeys stand on their hind legs to scan the ground for these camouflaged reptiles.
The specific and learned responses to various calls suggest that vervet monkeys are using a primitive form of language to communicate complex information about predators. Although not as developed as human language, this system of alarm calls represents a step towards symbolic communication seen in human language. The system allows for a form of natural selection where those who can accurately understand and act upon such calls have better chances of survival.