Gorilla

Gorillas are large, herbivorous great apes that live in the tropical forests of equatorial Africa. They belong to the genus Gorilla and are divided into two species: the eastern gorilla and the western gorilla, with either four or five subspecies. Their DNA is very similar to that of humans, sharing 96 to 99% depending on the comparison, making them our closest living relatives after bonobos and chimpanzees.

Gorillas are the largest living primates, with heights between 1.25 and 1.8 m (4 ft 1 in and 5 ft 11 in), weights from 68 to 227 kg (150 to 500 lb), and arm spans up to 2.6 m (8 ft 6 in). They usually live in troops led by a silverback male. Eastern gorillas have darker fur compared to western gorillas, along with some other small differences. In the wild, gorillas typically live for 35–40 years.

Their habitats are tropical or subtropical forests across Sub-Saharan Africa, ranging from sea level to high mountain elevations. Mountain gorillas live in the Albertine Rift montane cloud forests of the Virunga Volcanoes, while lowland gorillas inhabit dense forests and swamps. There are approximately 316,000 western gorillas and 5,000 eastern gorillas left in the wild. Both species are critically endangered, mainly due to threats like poaching, habitat loss, and disease, but conservation efforts are helping in some areas.

History and etymology

The word gorilla comes from stories about an explorer named Hanno the Navigator from around 500 BC. He was from Carthage and traveled along the African coast near what is now Sierra Leone. His team saw people with hairy bodies and called them Gorillae. We aren’t sure if these were gorillas, another type of ape, or even humans.

Later, in 1847, two scientists, Thomas Staughton Savage and Jeffries Wyman, officially named the western gorilla after seeing specimens from Liberia. They used the name Troglodytes gorilla, which came from an ancient word for “hairy women.”

Evolution and classification

Gorillas share a close family connection with chimpanzees and humans, splitting from a common ancestor about 7 million years ago. Their DNA is very similar to ours, differing by only about 1.6% on average.

Gorillas were once thought to be one species with three subspecies. Now, scientists agree there are two species, each with two subspecies. These species developed separately during the Ice Age when their forest homes became isolated. Researchers continue to study the relationships between different gorilla groups. One group, called the Bwindi gorilla, may be a third subspecies, but this is still being studied. Differences such as size, hair color, and facial features help scientists classify gorillas.

Characteristics

Wild male gorillas are large, weighing between 136 to 227 kg (300 to 500 lb), and they stand between 1.4 to 1.8 m (4 ft 7 in to 5 ft 11 in) tall. Females are smaller, weighing 68–113 kg (150–250 lb) and reaching heights of 1.25 to 1.5 m (4 ft 1 in to 4 ft 11 in). Adult males, called silverbacks, have a distinctive patch of silver hair on their backs.

Gorillas come in different types, with the eastern gorilla being darker and having thicker hair than the western gorilla. They have dark brown eyes and move mainly by walking on their knuckles, though they can stand upright for short periods. Gorillas share many traits with humans, including fingerprints, and they can live up to 40 years in the wild, though some zoo gorillas have lived longer.

Distribution and habitat

Gorillas live in the tropical forests of equatorial Africa. The two species of gorillas are 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.

Gorillas can be found in many different habitats, from montane forest to swampland. Eastern gorillas live in forests that are high up in the mountains, while western gorillas live in both lowland swamp forests and montane forests. These great apes adapt well to various environments across their African homes.

Ecology

Gorillas spend their days resting, traveling, and feeding. Mountain gorillas mostly eat leaves, stems, and shoots, while eastern lowland gorillas eat more fruit and insects. Western lowland gorillas rely heavily on fruit and travel far each day to find it. Surprisingly, gorillas sometimes climb trees to feed, especially on leaves.

Gorillas build simple nests from branches and leaves each night to sleep in. These nests are usually on the ground, and young gorillas stay close to their mothers until they are old enough to build their own. A silverback gorilla will protect its group from predators or humans, even if it means risking its own life.

Behaviour

Gorillas live in groups called troops. These groups usually have one adult male, called a silverback, along with several adult females and their young. Sometimes, there are multiple males in a group too. The silverback is named for the patch of silver hair on his back that appears when he becomes mature. He leads the group, makes decisions, and keeps everyone safe.

Females become mature at around 10 to 12 years old, and males at 11 to 13 years. Gorilla mothers take care of their babies closely for the first few years. Babies stay near their mothers for about five months and gradually spend more time away as they grow older. Gorillas communicate with each other using different sounds, like grunts, barks, and roars. These sounds help them talk to each other, warn of danger, or show they are happy.

Intelligence

Further information: Primate cognition

See also: Great ape language

Gorillas are known to be very smart. Some gorillas in zoos have learned to use sign language, like Koko. They can laugh, feel sadness, form strong family ties, and even think about the past and future. Researchers think gorillas might have feelings about things that are spiritual or religious. They also have different cultures in different places, such as special ways to prepare food, and they can even choose which colors they like.

Further information: Tool use by animals § Gorillas

Scientists discovered that gorillas can use tools, just like other great apes. In 2005, a female gorilla in the Nouabalé-Ndoki National Park in the Republic of Congo used a stick to check how deep the water was. Another gorilla used a tree stump to cross water and catch food. Even a young gorilla was seen using rocks to crack open nuts. This shows how clever gorillas really are.

Scientific study

American physician Thomas Staughton Savage collected the first gorilla bones during his time in Liberia. In 1847, he and naturalist Jeffries Wyman wrote the first scientific description of gorillas, calling them Troglodytes gorilla, which we now know as the western gorilla.

Later, explorer Paul Du Chaillu was the first Westerner to see a live gorilla in Africa between 1856 and 1859. He brought gorilla specimens to the UK in 1861.

Serious scientific study of gorillas began in the 1920s. Carl Akeley from the American Museum of Natural History traveled to Africa to study and preserve gorillas. After World War II, researcher George Schaller conducted the first detailed study of mountain gorillas in their natural habitat. Later, Dian Fossey carried out extensive research that helped correct many old myths about gorillas, showing they are not naturally violent.

Genome sequencing

Gorillas were the next-to-last great ape to have their genes mapped. Scientists studied the DNA of a female western lowland gorilla named Kamilah. This helped us learn more about human evolution. Even though chimpanzees are our closest living relatives, 15% of human DNA is more similar to gorillas. The study also showed that changes in hearing genes thought to be linked to human language also happened in gorillas.

Captivity

Gorillas have been kept in western zoos since the 19th century. The care of these gorillas improved greatly in the late 1920s, and Colo of the Columbus Zoo and Aquarium was the first gorilla born in captivity.

To help captive gorillas feel calmer, zoos use privacy screens and play natural sounds instead of loud music. These changes help reduce stressful behaviors in the gorillas. Researchers now believe it's important to consider each gorilla's individual needs, such as age and personality, to ensure their well-being.

Conservation status

All gorilla species and subspecies are endangered or critically endangered. They are protected by international laws to prevent trading and hunting. There are around 316,000 western lowland gorillas in the wild, with fewer eastern lowland and mountain gorillas remaining.

Gorillas face threats like habitat destruction and diseases such as Ebola and COVID-19. Conservation efforts include international agreements and projects to protect their habitats and prevent hunting.

Cultural significance

In parts of Cameroon, such as the Lebialem highlands, local traditions say that a person's life is linked to a gorilla through totems; if the gorilla dies, the person connected to it will also pass. Many indigenous groups have rich knowledge about gorillas. The Baka people, for example, have special names for different types of gorillas based on their age and relationships.

Gorillas have appeared often in stories, movies, and games. Early films sometimes showed them as scary or aggressive, but more recent stories, like Gorillas in the Mist, show them in a kinder light. They have been characters in comics, cartoons, and video games, such as Donkey Kong.