Green Monkey is a vegetarian, frugivorous primate with a black face, light greyish coat belonging in the Suborder Simiae and family, Cercopthecidae. Vervet monkeys (also called Grivet or Green Monkey) have a head-body length of 41 to 62 cm and a tail length of 53-72 cm. They have cheek-pouches allowing them to forage and store food to be eaten later. Males may reach a body-weight of up to 8 kg, females are much lighter. Gestation period is for 165 days. Unlike other guenons, vervet monkeys live in more open country.
Nigerian Monkeys have been objects of research from University of St. Andrews, Scotland zoologists, Dr. Arnold and Zuberbühler who investigated the possible hints that may be available on the origin of human language. Green Monkeys, called Aaya in Yoruba, are known to have specific alarm calls for different predators. Vervet monkeys have one call for eagles, another for snakes and a third for leopards. But the connection to language is unconvincing due to lack of evidence that the calls are words.
Isolation of HIV-like viruses from African Green Monkeys and macaques has raised the possibility that AIDS has somehow been passed to humans from non-human primates. Such transmission could have been an isolated, rare event, with HIV evolving independently from a single point of origin. To date, African green monkeys (Cercopithecus aethiops, or vervets) are the only species reported to have an AIDS-type virus in the wild.