Gorillas are herbivorous, predominantly ground-dwelling great apes that inhabit 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 95 to 99 per cent depending on what is included and they are the next closest living relatives to humans after chimpanzees and bonobos.
Gorillas are considered highly intelligent. A few individuals in captivity, such as Koko, have been taught a subset of sign language. Like the other great apes, gorillas can laugh, grieve, have “rich emotional lives”, develop strong family bonds, make and use tools, and think about the past and future. Some researchers believe gorillas have spiritual feelings or religious sentiments.
The gorilla is robust and powerful, with an extremely thick, strong chest and a protruding abdomen. Both skin and hair are black. The face has large nostrils, small ears, and prominent brow ridges. Adults have long, muscular arms that are 15–20 per cent longer than stocky legs.
Gorillas are the largest living primates, reaching heights between 1.25 and 1.8 metres, weights between 100 and 270 kg, and arm spans up to 2.6 metres, depending on species and sex. 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.
Wild male gorillas weigh 136 to 227 kg, while adult females weigh 68–113 kg. Adult males are 1.4 to 1.8 m tall, with an arm span that stretches from 2.3 to 2.6 m. Female gorillas are shorter at 1.25 to 1.5 m with smaller arm spans. Gorillas move around by knuckle-walking, although they sometimes walk upright for short distances, typically while carrying food or in defensive situations.
Gorillas live in stable family groups numbering from 6 to 30. The groups are led by one or two (occasionally more) silverback males that are related to each other, usually a father and one or more of his sons. Occasionally brothers lead a group. The other members are females, infants, juveniles and young adult males (blackbacks). Adult females join from outside the group and the young are offspring of silverbacks.
Gorillas have a patchy distribution. The range of the two species is separated by the Congo River and its tributaries. The western gorilla lives in west central Africa, while the eastern gorilla lives in east central Africa. Between the species, and even within the species, gorillas live in a variety of habitats and elevations. Gorilla habitat ranges from montane forest to swampland. Eastern gorillas inhabit montane and submontane forests.
A gorilla’s day is divided between rest periods and travel or feeding periods. Diets differ between and within species. The gorilla is active during the day (diurnal) and primarily terrestrial. Their diet is vegetarian; that of eastern gorillas includes leaves, stalks, and shoots, but western gorillas eat much more fruit. Gorillas generally dislike water, but in some areas, such as the Sangha-Ndoki region on the borders of Cameroon, the Republic of the Congo (Brazzaville), and the Central African Republic, they wade waist-deep into swampy clearings to feed on aquatic plants. Gorillas spend much of their time foraging and resting, with the group travelling a few hundred metres between several daily feeding bouts.
Females mature at 10–12 years and males at 11–13 years. A female’s first ovulatory cycle occurs when she is six years of age and is followed by a two-year period of adolescent infertility. The oestrous cycle lasts 30–33 days. Female mountain gorillas first give birth at 10 years of age and have four-year interbirth intervals. Males can be fertile before reaching adulthood. Gorillas mate year-round. Females will pursue 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 a female preference, but females can be forced to mate with multiple males.
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 with other youngsters.
Although western gorillas are more numerous than their eastern counterparts, the IUCN still classifies both subspecies as critically endangered because their populations continue to decline from the effects of poaching and habitat loss.
* In Cameroon’s Lebialem highlands, folk stories connect people and gorillas via totems; a gorilla’s death means the connected person will die also. This creates a local conservation ethic.
*Even far from where gorillas live, savannah tribes pursue “cult-like worship” of the apes
*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 in many aspects of popular culture and media.
*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).
*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.
*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.
