Gorilla

Gorillas are the largest living primates, native to the tropical forests of equatorial Africa. There are two species - the eastern gorilla and the western gorilla - divided into either four or five subspecies, with differences in fur colour, build, and facial shape between them.

Male gorillas are powerfully built, standing 1.4 to 1.8 m tall and weighing up to 227 kg in the wild, with an arm span that can reach 2.6 m. Females are noticeably smaller, typically 1.25 to 1.5 m tall and weighing 68 to 113 kg. Adult males develop a distinctive patch of silver hair across their backs as they mature, which is why they are known as silverbacks.

Gorillas are wild animals of tropical and subtropical forests in a small part of sub-Saharan Africa, and both species are classified as Critically Endangered by the IUCN. Around 316,000 western gorillas and only about 5,000 eastern gorillas are thought to remain in the wild.

Gorillas share a common ancestor with chimpanzees and humans, with the three groups having diverged roughly 7 million years ago. The DNA of gorillas is 96 to 99% similar to that of humans, making them our next closest living relatives after bonobos and chimpanzees. The separate gorilla species and subspecies developed from a single ancestral type during the Ice Age, when their forest habitats shrank and became isolated from one another.

The word gorilla traces back to the Carthaginian explorer Hanno the Navigator, around 500 BC, whose expedition to the west African coast encountered beings described as "hairy women" that interpreters called Gorillae. Whether these were what we now call gorillas remains unknown. In 1625 Andrew Battel mentioned the animal under the name Pongo, describing a giant, hairy creature that walked upright and went about in groups.

The western gorilla was formally described by the American physician Thomas Staughton Savage and naturalist Jeffries Wyman in 1847, from specimens obtained in Liberia. The first westerner to see a live gorilla was the explorer Paul Du Chaillu, during travels through western equatorial Africa between 1856 and 1859. Systematic scientific study of gorillas in the wild did not begin until the 1920s, with the most comprehensive early research on mountain gorillas carried out by Dian Fossey, whose work overturned many myths - including the widespread belief that gorillas are violent.

Gorillas live in social groups called troops, typically led by a silverback - a mature male aged over 12 years. The silverback makes decisions for the group, mediates conflicts, leads others to feeding sites, and protects the troop, sometimes at the cost of his own life. Younger males, known as blackbacks, may assist with protection.

Gorillas are considered highly intelligent. They can laugh, grieve, form strong family bonds, use tools, and show what researchers describe as rich emotional lives. In the wild, gorillas have been observed using sticks to gauge the depth of water and tree stumps as bridges, and in 2005 a two-and-a-half-year-old gorilla was seen using rocks to smash open palm nuts. Different gorilla populations show distinct cultural habits around food preparation.

Gorillas communicate through 25 recognised vocalisations. Grunts and barks are common during travel, while deep rumbling belches signal contentment during feeding and rest. Silverbacks produce screams and roars as alarm calls. When threatened, gorillas use a ritualised nine-step display - including chest-beating with cupped hands, throwing vegetation, and thumping the ground - to intimidate rivals without resorting to physical fighting.

Gorillas are primarily herbivorous, eating leaves, stems, shoots, and fruit, though some populations also eat insects such as ants and termites. They build a fresh nest of branches and leaves each day for sleeping, and sleep an average of 12 hours a day.

A gorilla's lifespan in the wild is normally 35 to 40 years. In rare circumstances, zoo gorillas may live for 50 years or more, and the oldest living gorilla, Fatou, is 69 years old.

Gorillas are susceptible to many of the same diseases as humans. Outbreaks of the Ebola virus have had devastating effects on wild gorilla populations - a 2006 study estimated that more than 5,000 gorillas may have died in recent outbreaks in central Africa. In 2004, a population of several hundred gorillas in the Republic of Congo was essentially wiped out by Ebola. In captivity, gorillas have also been observed to be infected with COVID-19.

Western lowland gorillas are considered one of the zoonotic origins of HIV/AIDS, as the simian immunodeficiency virus (SIVgor) that infects them is similar to a strain of HIV-1. Beyond infectious disease, threats to wild gorillas include poaching and habitat destruction, both of which contribute to their Critically Endangered status.

This is general awareness only, not veterinary advice. If you find an injured or unwell wild animal, contact a vet or a wildlife rescue.

Are gorillas really closely related to humans?

They are our next closest living relatives after bonobos and chimpanzees, having shared a common ancestor with humans and chimpanzees around 7 million years ago.

How long do gorillas live?

A gorilla's lifespan is normally between 35 and 40 years, although zoo gorillas may live for 50 years or more in rare circumstances.

Are gorillas aggressive and dangerous?

Gorillas are not naturally violent. Research by Dian Fossey and others disproved the long-standing myth that they are aggressive. Conflicts within troops are most often resolved through displays and threat behaviours rather than physical fighting. Silverbacks will defend their troop if attacked, and although severe aggression is rare in stable groups, when two mountain gorilla groups meet the silverbacks can sometimes fight to the death.

What do gorillas eat?

Gorillas are primarily herbivorous. Mountain gorillas eat mainly leaves, stems, pith, and shoots, while western lowland gorillas rely more heavily on fruit. Some populations also eat insects, particularly ants and termites.

Do gorillas carry diseases that can spread to people?

Some can - gorillas are susceptible to diseases that humans also get infected by. Western lowland gorillas are considered one of the origins of HIV/AIDS, and gorillas have been severely affected by outbreaks of Ebola. In captivity, gorillas have also been observed to be infected with COVID-19.

How many gorillas are left in the wild?

There are thought to be around 316,000 western gorillas and approximately 5,000 eastern gorillas remaining in the wild. Both species are classified as Critically Endangered, and threats to their survival include poaching, habitat destruction, and disease.

Like humans, gorillas have individual fingerprints - no two are the same.

Gorillas rarely need to drink water directly, because the succulent vegetation they eat is made up of almost half water, and they also consume morning dew.

The chest-beat that silverbacks are famous for is not just for show - the frequency of the sound varies with the gorilla's size, with larger individuals producing a deeper beat. Gorillas beat their chests most often when females are ready to mate.

Gorillas sleep an average of 12 hours a day and build a brand new nest of branches and leaves every single day - they never sleep in the same nest twice.

The name gorilla itself comes from an ancient Carthaginian expedition from around 500 BC, whose members encountered beings on the west African coast that their interpreters called Gorillae - a word meaning a tribe of hairy women.