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Gorillas are large, primarily herbivorous, that live in the tropical forests of equatorial Africa. The genus Gorilla is divided into two species: the eastern gorilla and the western gorilla, and either four or five subspecies. The DNA of gorillas is highly similar to that of humans, from 96 to 99% depending on what is included, and they are the next closest living relatives to after the bonobos and chimpanzees.
Gorillas are the largest living , reaching heights between , weights between , and arm spans up to , depending on species and sex. They tend to live in troops, with the leader being called a silverback. The eastern gorilla is distinguished from the western by darker fur colour and some other minor morphological differences. Gorillas tend to live 35–40 years in the wild.
Gorillas' natural habitats cover tropical or subtropical forest in Sub-Saharan Africa. Although their range covers a small percentage of Sub-Saharan Africa, gorillas cover a wide range of elevations. The mountain gorilla inhabits the Albertine Rift montane of the Virunga Volcanoes, ranging in altitude from . Lowland gorillas live in dense forests and lowland swamps and marshes as low as sea level, with western lowland gorillas living in Central West African countries and eastern lowland gorillas living in the Democratic Republic of the Congo near its border with Rwanda.
There are thought to be around 316,000 western gorillas in the wild, and 5,000 eastern gorillas. Both species are classified as Critically Endangered by the IUCN; all subspecies are classified as Critically Endangered with the exception of the mountain gorilla, which is classified as Endangered. There are many threats to their survival, such as poaching, habitat destruction, and disease, which threaten the survival of the species. However, conservation efforts have been successful in some areas where they live.
In 1625 Andrew Battel mentioned the existence of the animal, under the name Pongo:
A century and a half after Battel's story was published, one writer called Radermacher wrote that "the large species, described by Buffon and other authors as of the size of a man, is held by many to be a Chimera."
The American physician and missionary Thomas Staughton Savage and naturalist Jeffries Wyman first described the western gorilla in 1847 from specimens obtained in Liberia. They called it Troglodytes gorilla, using the then-current name of the chimpanzee genus. The species name was derived , as described by Hanno.
The proposed third subspecies of Gorilla beringei, which has not yet received a trinomen, is the Bwindi population of the mountain gorilla, sometimes called the Bwindi gorilla.
Some variations that distinguish the classifications of gorilla include varying density, size, hair colour, length, culture, and facial widths. Population genetics of the lowland gorillas suggest that the western and eastern lowland populations diverged around 261 thousand years ago.
Gorillas move around by knuckle-walking, although they sometimes walk upright for short distances, typically while carrying food or in defensive situations. A 2018 study investigating the hand posture of 77 mountain gorillas at Bwindi Impenetrable National Park (8% of the population) found that knuckle walking was done only 60% of the time, and they also supported their weight on their fists, the backs of their hands/feet, and on their palms/soles (with the digits flexed). Such a range of hand postures was previously thought to have been used by only orangutans. Studies of gorilla handedness have yielded varying results, with some arguing for no preference for either hand, and others right-hand dominance for the general population.
Studies have shown gorilla blood is not reactive to anti-A and anti-B monoclonal antibodies, which would, in humans, indicate type O blood. Due to novel sequences, though, it is different enough to not conform with the human ABO blood group system, into which the other great apes fit.
A gorilla's lifespan is normally between 35 and 40 years, although zoo gorillas may live for 50 years or more in Oldest hominids. At , Fatou is both the oldest living gorilla and oldest living female gorilla. The oldest male gorilla ever was Ozoum, who reached the final age of 61 years, 24 days. The oldest living male gorilla is Guhonda, aged .
Mountain gorillas live in montane forests at the higher end of the elevation range, while eastern lowland gorillas live in submontane forests at the lower end. In addition, eastern lowland gorillas live in montane bamboo forests, as well as lowland forests ranging from in elevation. Western gorillas live in both lowland swamp forests and montane forests, at elevations ranging from sea level to . Western lowland gorillas live in swamp and lowland forests ranging up to , and Cross River gorillas live in low-lying and submontane forests ranging from .
Eastern lowland gorillas have more diverse diets, which vary seasonally. Leaves and pith are commonly eaten, but fruits can make up as much as 25% of their diets. Since fruit is less available, lowland gorillas must travel farther each day, and their home ranges vary from , with day ranges . Eastern lowland gorillas will also eat insects, preferably ants. Western lowland gorillas depend on fruits more than the others and they are more dispersed across their range. They travel even farther than the other gorilla subspecies, at per day on average, and have larger home ranges of . Western lowland gorillas have less access to terrestrial herbs, although they can access aquatic herbs in some areas. Termites and ants are also eaten.
Gorillas rarely drink water "because they consume succulent vegetation that is almost half water as well as morning dew", although both mountain and lowland gorillas have been observed drinking.
Gorillas make a new nest to sleep on each day; even if remaining in the same place, they do not use the previous one. Usually, they are made an hour before dusk, to be ready to sleep when night falls. Gorillas sleep longer than humans, an average of 12 hours per day.
Mature males also tend to leave their groups and establish their own troops by attracting emigrating females. However, male mountain gorillas sometimes stay in their natal troops and become subordinate to the silverback. If the silverback dies, these males may be able to become dominant or mate with the females. This behaviour has not been observed in eastern lowland gorillas. In a single male group, when the silverback dies, the females and their offspring disperse and find a new troop. Without a silverback to protect them, the infants will likely fall victim to infanticide. Joining a new group is likely to be a tactic against this. However, while gorilla troops usually disband after the silverback dies, female eastern lowlands gorillas and their offspring have been recorded staying together until a new silverback transfers into the group. This likely serves as protection from leopards. The silverback is the centre of the troop's attention, making all the decisions, mediating conflicts, determining the movements of the group, leading the others to feeding sites, and taking responsibility for the safety and well-being of the troop. Younger males subordinate to the silverback, known as blackbacks, may serve as backup protection. Blackbacks are aged between 8 and 12 years and lack the silver back hair. The bond that a silverback has with his females forms the core of gorilla social life. Bonds between them are maintained by grooming and staying close together. Females form strong relationships with males to gain mating opportunities and protection from predators and infanticidal outside males. However, aggressive behaviours between males and females do occur, but rarely lead to serious injury. Relationships between females may vary. Maternally related females in a troop tend to be friendly towards each other and associate closely. Otherwise, females have few friendly encounters and commonly act aggressively towards each other.
Females may fight for social access to males and a male may intervene. Male gorillas have weak social bonds, particularly in multiple-male groups with apparent dominance hierarchies and strong competition for mates. Males in all-male groups, though, tend to have friendly interactions and socialise through play, grooming, and staying together, and occasionally they even engage in homosexual interactions. Severe aggression is rare in stable groups, but when two mountain gorilla groups meet the two silverbacks can sometimes engage in a fight to the death, using their canines to cause deep, gaping injuries.
Females will purse their lips and slowly approach a male while making eye contact. This serves to urge the male to mount her. If the male does not respond, then she will try to attract his attention by reaching towards him or slapping the ground. In multiple-male groups, solicitation indicates female preference, but females can be forced to mate with multiple males. Males incite copulation by approaching a female and displaying at her or touching her and giving a "train grunt". Copulation typically lasts 1–2 minutes, but can last as long as 20 minutes. Recently, gorillas have been observed engaging in face-to-face sex, a trait once considered unique to humans and .
Gorilla infants are vulnerable and dependent, thus mothers, their primary caregivers, are important to their survival. Male gorillas are not active in caring for the young, but they do play a role in socialising them to other youngsters. The silverback has a largely supportive relationship with the infants in his troop and shields them from aggression within the group. Infants remain in contact with their mothers for the first five months and mothers stay near the silverback for protection. Infants suckle at least once per hour and sleep with their mothers in the same nest.
Infants begin to break contact with their mothers after five months, but only for a brief period each time. By 12 months old, infants move up to from their mothers. At around 18–21 months, the distance between mother and offspring increases and they regularly spend time away from each other. In addition, nursing decreases to once every two hours. Infants spend only half of their time with their mothers by 30 months. They enter their juvenile period at their third year, and this lasts until their sixth year. At this time, gorillas are weaned and they sleep in a separate nest from their mothers. After their offspring are weaned, females begin to ovulate and soon become pregnant again. The presence of play partners, including the silverback, minimizes conflicts in weaning between mother and offspring.
For this reason, conflicts are most often resolved by displays and other threat behaviours that are intended to intimidate without becoming physical. As a result, fights do not occur very frequently. The charge display is unique to gorillas. The entire sequence has nine steps: (1) progressively quickening hooting, (2) symbolic feeding, (3) rising bipedally, (4) throwing vegetation, (5) chest-beating with cupped hands, (6) one leg kick, (7) sideways running, two-legged to four-legged, (8) slapping and tearing vegetation, and (9) thumping the ground with palms to end display.
A gorilla's chest-beat may vary in frequency depending on its size. Smaller ones tend to have higher frequencies, while larger ones tend to be lower. They also do it the most when females are ready to mate.
In September 2005, a two-and-a-half-year-old gorilla in the Republic of Congo was discovered using rocks to smash open palm nuts inside a game sanctuary. While this was the first such observation for a gorilla, over 40 years previously, chimpanzees had been seen using tools in the wild 'fishing' for termites. Nonhuman great apes are endowed with semiprecision grips, and have been able to use both simple tools and even weapons, such as improvising a club from a convenient fallen branch.
The first systematic study was not conducted until the 1920s, when Carl Akeley of the American Museum of Natural History traveled to Africa to hunt for an animal to be shot and stuffed. On his first trip, he was accompanied by his friends Mary Bradley, a mystery writer, her husband, and their young daughter Alice, who would later write science fiction under the pseudonym James Tiptree Jr. After their trip, Mary Bradley wrote On the Gorilla Trail. She later became an advocate for the conservation of gorillas, and wrote several more books (mainly for children). In the late 1920s and early 1930s, Robert Yerkes and his wife Ava helped further the study of gorillas when they sent Harold Bigham to Africa. Yerkes also wrote a book in 1929 about the great apes.
After World War II, George Schaller was one of the first researchers to go into the field and study primates. In 1959, he conducted a systematic study of the mountain gorilla in the wild and published his work. Years later, at the behest of Louis Leakey and the National Geographic, Dian Fossey conducted a much longer and more comprehensive study of the mountain gorilla. When she published her work, many misconceptions and myths about gorillas were finally disproved, including the myth that gorillas are violent.
Western lowland gorillas ( G. g. gorilla) are believed to be one of the zoonotic origins of HIV/AIDS. The SIVgor Simian immunodeficiency virus that infects them is similar to a certain strain of HIV-1. (2025). 9780123736017 ISBN 9780123736017
Captive gorillas exhibit stereotypic behaviors, including eating such as regurgitation, reingestion and self-injurious or conspecific aggression, pacing, rocking, sucking of fingers or lip smacking, and overgrooming. Negative vigilance of visitor behaviors have been identified as starting, posturing and charging at visitors. Groups of bachelor gorillas containing young silverbacks have significantly higher levels of aggression and wounding rates than mixed age and sex groups.
The use of both internal and external privacy screens on exhibit windows has been shown to alleviate stresses from visual effects of high crowd densities, leading to decreased stereotypic behaviors in the gorillas. Playing naturalistic auditory stimuli as opposed to classical music, rock music, or no auditory enrichment (which allows for crowd noise, machinery, etc. to be heard) has been noted to reduce stress behavior as well. Enrichment modifications to feed and foraging, where clover-hay is added to an exhibit floor, decrease stereotypic activities while simultaneously increasing positive food-related behaviors.
Recent research on captive gorilla welfare emphasizes a need to shift to individual assessments instead of a one-size-fits-all group approach to understanding how welfare increases or decreases based on a variety of factors. Individual characteristics such as age, sex, personality and individual histories are essential in understanding that stressors will affect each individual gorilla and their animal welfare differently.
Conservation efforts include the Great Apes Survival Project, a partnership between the United Nations Environment Programme and the UNESCO, and also an international treaty, the Agreement on the Conservation of Gorillas and Their Habitats, concluded under UNEP-administered Bonn Convention. The Gorilla Agreement is the first legally binding instrument exclusively targeting gorilla conservation; it came into effect on 1 June 2008. Governments of countries where gorillas live placed a ban on their killing and trading, but weak law enforcement still poses a threat to them, since the governments rarely apprehend poachers, traders and consumers that rely on gorillas for profit.
In 1911, the anthropologist Albert Jenks noted the Bulu people's knowledge of gorilla behaviour and ecology, and their gorilla stories. In one such story, "The Gorilla and the Child", a gorilla speaks to people, seeking help and trust, and stealing a baby; a man accidentally kills the baby while attacking the gorilla. Even far from where gorillas live, savannah tribes pursue "cult-like worship" of the apes. Some beliefs are widespread among indigenous peoples. The Fang language name for gorilla is ngi while the Bulu name is njamong; the root ngi means fire, denoting a positive energy. From the Central African Republic to Cameroon and Gabon, stories of reincarnations as gorillas, totems, and transformations similar to those recorded by Du Chaillu are still told in the 21st century.
Since gaining international attention, gorillas have been a recurring element of many aspects of popular culture and media. They were usually portrayed as murderous and aggressive. Inspired by Emmanuel Frémiet's Gorilla Carrying off a Woman, gorillas have been depicted kidnapping human women. This theme was used in films such as Ingagi (1930) and most notably King Kong (1933). The comedic play The Gorilla, which debuted in 1925, featured an escaped gorilla taking a woman from her house. Several films would use the "escaped gorilla" trope including The Strange Case of Doctor Rx (1942), The Gorilla Man (1943), Gorilla at Large (1954) and the Disney cartoons The Gorilla Mystery (1930) and Donald Duck and the Gorilla (1944).
Gorillas have been used as opponents to jungle-themed heroes such as Tarzan and Sheena, Queen of the Jungle, as well as superheroes. The DC Comics supervillain Gorilla Grodd is an enemy of the Flash. Gorillas also serve as antagonists in the 1968 film Planet of the Apes. More positive and sympathetic portrayals of gorillas include the films Son of Kong (1933), Mighty Joe Young (1949), Gorillas in the Mist (1988) and Instinct (1999) and the 1992 novel Ishmael. Gorillas have been featured in video games as well, notably Donkey Kong.
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