Mammals
Gorilla
Gorilla · also called gorillas, western gorilla, eastern gorilla
A gorilla is the biggest primate there is: an adult male can weigh 200 kilograms, bend thick bamboo one-handed, and drive off a leopard, yet it spends most of its day quietly eating leaves and stems. Gorillas live in tight family groups run by a single silver-backed male, they build a fresh nest to sleep in every night, and they share about 98 percent of their DNA with us.
Overview
Gorillas are the genus Gorilla, two species — the western gorilla of the Congo basin lowlands and the eastern gorilla further east — each with two subspecies, the rarest being the Cross River gorilla (~300) and the most famous the mountain gorilla (~1,000). They live in rainforest and montane forest from sea level to 4,000 m and are overwhelmingly plant eaters: mountain gorillas eat almost nothing but leaves and stems, western lowland gorillas eat a lot of fruit.
The silverback
At 12–15 years a male’s back turns silver-grey, and a silverback leads a family group of several females and young, deciding where to feed and rest and defending them with chest-beating displays and bluff charges that usually replace an actual fight. Gorillas are shy and non-aggressive despite their power.
Close to us
Gorillas share ~98% of human DNA, use simple tools in the wild, learn hundreds of signs in captivity, and show grief, play-laughter, and mirror self-recognition. Every gorilla over about three builds a fresh sleeping nest each night.
Status
Both species are Critically Endangered. The western gorilla is falling fast from bushmeat hunting, logging, mining, and Ebola, which has killed roughly a third of gorillas in affected areas; Grauer’s gorilla has more than halved in twenty years. The mountain gorilla is the exception — intensive protection, ecotourism revenue, and veterinary care have grown it past 1,000, the only great ape currently increasing.
Gorilla: common questions
How strong is a gorilla?
Very, though exact figures are hard to pin down because few controlled tests have been done on wild adults. An adult male gorilla is estimated to be several times stronger than a fit adult human for tasks like pulling and lifting, thanks to a much greater muscle mass, a robust skeleton, and long powerful arms, and observations of gorillas bending 5-centimetre bamboo, snapping thick branches, and tearing open tough vegetation support this. Old claims of a gorilla lifting 900 kilograms or more come from a single unverified account and are not reliable. What is clear is that a gorilla is far stronger than a person and could easily injure or kill one, but they almost never do, because they are not aggressive toward humans unless cornered or provoked.
Why do gorillas beat their chests?
Chest-beating is a communication display, used mainly by silverback males but also by females and young. A gorilla rises onto its legs, cups its hands, and slaps them rapidly against its chest, producing a hollow pok-pok-pok that carries over a kilometre through the forest. It advertises the animal's size and vigour, signals emotional state, and is used to intimidate rival males, warn off threats, and coordinate group movement, and recent research shows that larger males produce lower-pitched beats, so the sound honestly conveys body size. Crucially, the display usually replaces a fight rather than leading to one; a smaller male that hears a big silverback beating his chest is likely to withdraw.
What is the difference between a gorilla and a chimpanzee?
Both are African great apes, but they differ in size, diet, social structure, and temperament. A gorilla is far larger, with an adult male two to four times the weight of a chimpanzee, is mostly a ground-dwelling plant-eater, and lives in stable, cohesive family groups led by one dominant silverback. A chimpanzee is smaller, more agile, spends more time in trees, is an omnivore that hunts monkeys and other prey, and lives in large fluid communities of dozens of individuals that split and merge, with shifting male alliances and, at times, lethal intergroup violence. Chimpanzees are also slightly more closely related to humans than gorillas are.
Are gorillas dangerous to people?
They can be, given their strength, but attacks on humans are rare and almost always defensive. Gorillas are shy and avoid people, and habituated groups used to researchers and tourists tolerate close observation calmly as long as visitors stay quiet, keep a respectful distance, and do not stare directly or block the group's path. A silverback may bluff-charge someone who alarms him, roaring and slapping the ground, and the correct response is to crouch, look down, and stay still until he loses interest. Serious injuries happen mainly to poachers, to people who surprise a gorilla at close range, or to those who ignore guide instructions on a trek.