Most people picture primates as creatures that live on a diet of fruit and leaves, but their diet is far more complex. Many primate species, from the smallest monkeys to the largest apes, regularly consume animal matter, actively hunting and scavenging for protein. This consumption is driven by both ecological necessity and nutritional benefits. The types of prey and methods of obtaining it vary widely, revealing diverse feeding behaviors across the primate order.
The Spectrum of Primate Diets
The dietary habits of nonhuman primates are traditionally categorized based on their primary food source, with most species classified as omnivores. Major categories include frugivores (fruit focus) and folivores (leaves and foliage). Virtually all primates supplement their plant-based diets with animal protein. This animal matter ranges from invertebrates like insects and spiders to small vertebrates such as birds, eggs, and small mammals. Faunivores specialize in eating insects and other small animals, highlighting that while true carnivory is rare, animal consumption is widespread.
Highly Organized Primate Hunters
Among nonhuman primates, the common chimpanzee (Pan troglodytes) stands out for its highly coordinated hunting behavior and consumption of vertebrate prey. Their favorite prey is often the red colobus monkey, which can account for up to 80% of the meat in their diet in some regions. Chimpanzee hunts are organized events where individuals take on roles, such as “drivers” who push the prey, and “blockers” who cut off escape routes in the canopy. This cooperative strategy is necessary because the prey is difficult to capture in the dense forest environment.
Following a successful kill, the meat becomes a highly prized resource, leading to intense social excitement and competition. The carcass is often shared, reinforcing alliances and relationships within the community, especially among males. Certain species of baboons (Papio spp.) also frequently engage in active hunting, consuming small antelopes, hares, and other small mammals. This deliberate predation demonstrates a level of predatory sophistication rare among non-human primates.
Opportunistic Faunivory and Small Prey
While great apes hunt larger vertebrates, many smaller primates rely on invertebrate and small animal sources accessed opportunistically. Tarsiers, for example, are unique among primates as obligate faunivores; their diet consists entirely of animal matter. These small nocturnal hunters catch insects, lizards, and small bats using impressive leaps and specialized hand-eye coordination. Their specialized diet is reflected in their sharp, pointed molar cusps, which are adapted for piercing insect exoskeletons.
In the New World, capuchin monkeys (Cebus and Sapajus spp.) are well-documented for their resourcefulness in finding animal protein. Capuchins use stone tools as hammers and anvils to crack open nuts. They also use tools to access invertebrate prey, such as digging for fossorial arthropods or probing for insects in tree crevices. This demonstrates a flexible and intelligent approach to securing protein that is otherwise inaccessible.
The Nutritional Significance of Animal Protein
The drive for animal protein is rooted in the specific nutritional boost it provides, which is difficult to obtain from plant matter alone. Meat is a concentrated source of high-quality protein and fat, vital for energy and growth, especially for nursing females and developing juveniles. Animal matter consumption is particularly important for providing certain micronutrients, a concept known as the micronutrient hypothesis.
One of the most important nutrients is Vitamin B12, a cobalt-containing compound essential for nervous system function and DNA synthesis. Since plants and fungi do not produce B12, primates must obtain it from animal products. This nutritional requirement explains why meat-eating behavior, even in small amounts, is widespread and highly valued across the primate order.