However, it was later discovered that the nose colour used to separate these subspecies could change to white during pregnancy in females, as well as in general as animals aged, and E. patas pyrrhonotus in Kenya often did not have white noses,[1][5] thus Mammal Species of the World has classified E. patas as a monotypic species.

Colin Groves first argued the species was closely related to Cercopithecus aethiops in 1989, based on anatomical morphology.

However, a 2017 study proposed splitting E. patas into three species (E. patas sensu stricto, E. poliphaeus, and E. baumstarki) based on morphological differences and heavy geographic separation between taxa, with the IUCN Red List and American Society of Mammalogists following through with this.

The common patas monkey lives in multi-female groups of up to 60 individuals (although much larger aggregations have been reported).

[13] The common patas monkey feeds on insects, gum, seeds, and tubers, a diet more characteristic of much smaller primates.

[14] Variation in the female social structure of patas monkeys has been observed across different populations.

Higher rates of conflict over dense, but limited, food, such as fruit bushes, is associated with more stable, well defined dominance hierarchies than habitats with more diffuse resources, such as insects.

Dominance structure has relatively little effect on the probability of reconciliation occurring, except that the alpha-female is the least reconciliatory of the females.

This contrasts with an earlier study in which juveniles were observed to leave later, at sexual maturity, indicating that there may be variation between groups.

This may indicate weakening of matrilineal ties, rather than male aggression, as the main reason juveniles disperse from their natal group.

[18] Common patas monkeys have several distinct alarm calls that warn members in the group of predators.

[citation needed] The relationship between the patas monkey and the whistling thorn acacia may have inspired The Lorax by Dr.