The image of a gorilla happily eating a banana is a classic, yet misleading, cultural perception ingrained by popular media. The scientific reality of the gorilla’s natural diet and the characteristics of commercial bananas tell a story far different from the one commonly portrayed.
The Straight Answer: Gorillas and Wild Bananas
Wild gorillas may occasionally consume parts of a banana plant, but the fruit they encounter is vastly different from the commercial variety. Supermarket bananas, primarily the Cavendish cultivar, have been selectively bred for high sugar content and seedlessness. Wild bananas are fibrous, small, and filled with large, hard seeds, making them significantly less sweet than their cultivated relatives.
If a gorilla encounters a wild banana plant, it is more likely to consume the fibrous leaf sheaths, stems, and pith, which provide bulk and hydration. When gorillas raid plantations, they often eat the stems and leaves of the cultivated plant, not just the fruit. The common belief that gorillas love the sweet, soft fruit is largely a reflection of human preference, not a natural dietary staple.
The Natural Gorilla Diet: A Foraging Lifestyle
Gorillas are primarily herbivores whose natural diet is characterized by high fiber content and a very low sugar profile. They spend a large portion of their day foraging, consuming massive volumes of vegetation to meet their energy needs. An adult gorilla can consume up to 30 kilograms (66 pounds) of plant matter daily.
Their digestive system is adapted to process this tough, fibrous material, possessing an enlarged hindgut for fermentation by gut microbes. This process allows them to extract significant energy from plant cellulose, which is indigestible to many other mammals. The bulk of their diet consists of herbaceous stems, leaves, pith, and shoots, making them primarily folivores, or leaf-eaters.
Mountain gorillas subsist on a diet that is up to 86% leaves and stems due to the scarcity of fruit at high altitudes. Western and Eastern lowland gorillas consume more seasonal fruit, but these are diverse and fibrous, unlike high-sugar commercial varieties. Occasional insects, such as ants or termites, are consumed, providing a small source of protein to supplement their plant-based diet.
Health Concerns of Commercial Bananas
The high concentration of simple sugars (fructose and glucose) in commercial bananas is detrimental to a gorilla’s health when consumed in excess. The gorilla’s digestive system, optimized for fermenting low-sugar, high-fiber plants, struggles to process large amounts of rapidly digestible sugar. This often leads to gastrointestinal upset due to rapid fermentation in the gut.
Accredited zoos and sanctuaries have restricted or eliminated commercial bananas and other high-sugar fruits from primate diets. Historically, bananas were a cheap, available food source for captive animals, contributing to the popular myth. Modern dietary guidelines emphasize a diet rich in leafy green vegetables and high-fiber primate biscuits, limiting fruit to as little as 7% of the total intake, often used only as a training reward.
Excessive sugar consumption contributes to serious health issues in captive gorillas, including dental decay, obesity, and cardiovascular disease. Mimicking the wild diet’s nutritional composition—high fiber and low sugar—is now standard practice to promote better long-term health.