Apes are not carnivores, a fact easily confirmed by examining their natural feeding habits. Great apes are classified as either herbivores or omnivores, with diets heavily centered on plant matter. A carnivore requires that more than 70% of its diet consist of meat, a standard no great ape species meets. Their biology, from teeth to internal organs, is structured to process a high-fiber, plant-based diet.
Defining Dietary Classifications
Animals are categorized into dietary classes based on their primary source of nutrition. A carnivore’s diet is composed almost entirely of animal tissue. Herbivores subsist exclusively on plants and have specialized digestive systems to break down cellulose. Omnivores maintain a mixed diet of both plant and animal matter, allowing flexibility in consuming available food. Great apes, including gorillas, chimpanzees, and orangutans, fall into the herbivore or omnivore categories.
The Diverse Diets of Great Apes
The diets of great apes show significant variation, ranging from strictly plant-based to partially meat-inclusive. Gorillas are the most herbivorous of the group, consisting primarily of leaves, shoots, and stems. Mountain gorillas rely heavily on low-calorie vegetation and bamboo, consuming up to 60 pounds of food daily to meet their energy needs. Western lowland gorillas supplement their leafy diet with more fruit and occasional insects, but they remain fundamentally plant-eaters.
Chimpanzees and bonobos are the most omnivorous, often classified as frugivores because fruit makes up the largest portion of their diet. They consume a wide array of foods, including leaves, seeds, and roots, but also actively hunt and eat animal protein. Chimpanzees, in particular, engage in cooperative hunting of small mammals, such as various species of monkeys, and also consume invertebrates like termites and ants. Orangutans are primarily frugivores, with fruit comprising a significant percentage of their intake, which is supplemented with flowers, leaves, and insects.
Anatomical Evidence Supporting Ape Diets
The physical structure of apes provides clear evidence that they are not suited for a carnivorous lifestyle. True carnivores possess specialized shearing teeth, known as carnassials, which are designed to slice and tear muscle and sinew. Apes, however, have broad, flat molars with low, rounded cusps that are perfectly suited for the crushing and grinding of tough plant fibers. Their canines, while sometimes large in males for display and competition, do not function as the sharp, dagger-like weapons used by obligate carnivores for killing prey.
Furthermore, the length and structure of their digestive tract reflect an adaptation for processing large volumes of plant material. Apes have a relatively long digestive system, particularly a capacious colon that makes up about 50% of their total gut volume. This extended colon allows for the slow and complex fermentation of cellulose by gut microbes, a necessary process for extracting nutrients from fibrous plants. This is in stark contrast to obligate carnivores, which have short, simple digestive tracts that allow for the rapid transit and processing of easily digestible meat.