The question of why gorillas, which primarily eat plants, possess large, pointed teeth is a common source of confusion for many observers. These teeth are canines, not true fangs, and they present a paradox since the typical function of such teeth—tearing flesh—is absent from the gorilla’s diet. Gorillas are among the largest living primates and are known herbivores, yet the size of their canines suggests a purpose beyond simple vegetation processing. The answer lies not in their feeding habits but in their complex social structure and the evolutionary pressures of competition.
The Structure of Gorilla Teeth
Gorillas possess 32 teeth, the same number found in humans, and their dental formula is organized similarly with incisors, canines, premolars, and molars. While the canines are large, the rest of the gorilla’s dentition is perfectly adapted for a plant-based diet. Their broad, flat molars and premolars are robustly built for grinding and crushing large quantities of tough, fibrous vegetation, such as leaves, stems, bark, and bamboo shoots.
The sheer volume of coarse material mountain gorillas consume daily—up to 30 kilograms of plants—demands strong posterior teeth for efficient processing. The incisors are used for biting and cutting plant material, and the canines can assist in stripping bark or tough outer layers from plants. However, the specialized structure of the molars is the primary mechanism supporting their herbivorous lifestyle, demonstrating that the canines are not the main tools for sustenance.
Primary Function: Display and Intimidation
The main function of the gorilla’s large canines is social, serving as a visual signal of dominance and a tool for intimidation. These teeth are deployed during ritualized threat displays, which are used to resolve conflicts without resorting to injurious physical fighting. A gorilla, particularly a silverback, will often open its mouth in a wide gape, exposing the canines to deter rivals or external threats.
The canines are a central element in the multi-step charge display unique to gorillas. The display includes a sequence of escalating behaviors, such as hooting, rising bipedally, throwing vegetation, and chest-beating. The purpose of this performance is to signal strength and avoid actual combat, as severe aggression can result in serious injuries caused by those very canines. The teeth are weapons of last resort, used to signal the capacity for harm, thereby maintaining social order and protecting the group.
Sexual Dimorphism and Canine Size
The most pronounced feature of gorilla dentition is the significant size difference in canines between sexes, a trait known as sexual dimorphism. Adult male silverbacks possess canines that are larger and more prominent than those of females, sometimes growing up to two inches long. This difference is one of the strongest examples of sexual dimorphism among all great apes.
The larger canines in males are a secondary sexual characteristic, driven by the intense competition among males for breeding access to females, a process called intrasexual selection. Canine size signals the male’s fitness and dominance, enabling him to establish a hierarchy and defend his harem from competing males. The size of the male’s canines reinforces the threat display, as males with larger teeth are better equipped to project power and are consequently more successful at reproducing.