Gorilla

Quick Take

• Gorillas have a terrifying reputation in entertainment, yet their actual response to danger is almost the opposite of what movies show. See their shy nature →
• Sharing 98% of human DNA sounds impressive, but for wild gorillas that shared heritage is also a serious and growing vulnerability. Explore human threats →
• Captive gorillas can live nearly twice as long as those in the wild, but the reasons behind that gap are more troubling than they first appear. Compare wild vs. captive lifespans →
• The word 'gorilla' is over 2,500 years old, and its original meaning has nothing to do with the animal you picture. Trace the word's origins →

The name gorilla actually refers to four different subspecies of animals. They share approximately 98.3 percent of their DNA with humans, and they are smart enough to learn sign language and use tools. Gorillas are far from the wild, violent beasts they are portrayed as in entertainment, and they could even be considered rather shy. The wild population of gorillas is in rapid decline, and they are critically endangered. The average gorilla is as much as four times as strong as a human.

6 Incredible Gorilla Facts

• Despite their massive size and impressive strength, these great apes are primarily vegetarians.
• Wild gorillas live around 35 to 40 years, but the oldest captive gorilla on record, Fatou of Berlin Zoo, has lived past the age of 69.
• An adult is capable of bending an iron bar with only their hands.
• These animals are actually quite shy, and they will normally choose to flee if given the opportunity when threatened.
• Healthy adults have no natural predators.
• Gorillas are larger than other ape species and can weigh twice as much as the largest orangutans and more than five times as much as mandrills.

Classification and Scientific Name

Gorilla is the genus that is commonly used to refer to two species of great apes that are divided further into four total subspecies. The western gorilla (Gorilla gorilla) is split into the western lowland gorilla with the scientific name Gorilla gorilla gorilla and the Cross River gorilla (Gorilla gorilla diehli). The eastern gorilla (Gorilla beringei) comprises the eastern lowland gorilla (Gorilla beringei graueri), which is also known as the Grauer’s gorilla, and the mountain gorilla with the scientific name Gorilla beringei beringei.

These animals are members of the class Mammalia, the order Primates, and the family Hominidae. The term gorilla itself originates from a word in the ancient African local dialect along the west coast of the continent that translates roughly as “a hairy person”. This was first recorded by an explorer in the region over 2,500 years ago.

Evolution and Origin

The evolutionary history of gorillas is not well understood. However, population genetic data has helped researchers better understand the evolution of this species. Molecular geneticists have determined that the population of gorillas split into two groups (western and eastern gorillas) around 77,700 years ago.

The closest relatives of gorillas are humans and chimpanzees. Gorillas diverged from the human-chimpanzee lineage approximately 8 to 19 million years ago, while humans and chimpanzees later split from their common ancestor around 6 to 8 million years ago. Human gene sequences differ from gorilla gene sequences by only 1.6% on average. Gorillas were previously thought to be a single species with three subspecies (western lowland, eastern lowland, and mountain gorillas), but it is now accepted that there are two main species, and they each have two subspecies. All gorillas developed from a single ancestral type during the Ice Age, when their forest habitats shrank and became isolated from one another.

Appearance and Behavior

This is an impressively strong animal, and its appearance backs that up. They possess thick chests with wide shoulders and a protruding abdomen. Adults have long, heavily muscled arms that they use to help propel themselves on their knuckles. Gorillas are covered in black fur except for their faces, hands, and feet; older males also have bare chests. Adult males develop gray or silver hairs in a saddle pattern on their lower back, which is why mature males are often referred to as silverbacks. Mountain gorillas have noticeably longer hair than the other three species. Gorillas have uniquely shaped skulls within the animal kingdom.

Male gorillas can grow to nearly five and a half feet tall, with their weight ranging between 300 and 485 pounds. Females generally stand up to 4.5 feet tall and weigh 150 to 200 pounds. Gorillas in captivity tend to become overweight and may be much heavier than their wild counterparts. The largest recorded gorilla in captivity was Phil of the St. Louis Zoo, who died weighing 776 pounds; that’s bigger than a grizzly bear!

Despite their reputation in the entertainment industry as aggressive, gorillas are actually quite shy unless threatened or harassed. They live in family groups ranging from six members up to 30 that are led by one or two related silverbacks. Generally, the leadership pair is father and son, but it is not uncommon for brothers to lead a troop. The remainder of the group is composed of females, infants, and juveniles. They are active during the day and primarily move to feed.

Habitat

While all gorillas inhabit the tropical forests of Africa, the specific habitat varies widely depending on the subspecies. The western lowland gorilla lives in the rainforests between Cameroon and the Congo River. The Cross River gorilla resides in only a small forest area between Nigeria and Cameroon, directly on the Cross River. Grauer’s gorilla lives in the rainforests of Congo, and the mountain gorilla lives in the mountain forests of the border region of Rwanda, Uganda, and Congo.

A group of gorillas is called a troop or a band. A troop claims an area between one and 16 square miles, and they will walk short distances throughout that territory to feed. Several bands may inhabit the same area without conflict. They build nests of vegetation every night, either on the ground or in trees.

Diet

Most of these animals are vegetarian, but the western lowland gorilla also eats insects.

What does a gorilla eat?

Eastern gorillas thrive on leaves, shoots, and stalks of many different plants, while western gorillas eat more fruit. The western lowland gorilla will smash open termite and ant mounds to eat the insects inside and has been known to eat snails as well. These animals can eat as much as 40 pounds of plant matter per day.

Predators and Threats

The only true predator of these animals is a leopard. Leopards don’t commonly hunt gorillas due to their sheer size and strength. It makes much more sense for them to focus on less dangerous prey.

Sadly, the greatest threat to these animals comes from humans. Exposure to disease, deforestation, trophy hunting, and even subsistence hunting to feed logging crews have all taken a terrible toll on the gorilla population. Since they share 98 percent of their DNA with humans, many of the diseases that affect humans are also faced by gorilla populations. That is why conservation efforts have focused on eliminating physical contact between humans and wild gorilla populations, as their immune systems cannot handle the diseases that humans transmit.

What eats gorillas?

The short answer is: not much. Leopards can kill young animals, but they do not have many opportunities since the young rarely stray far from the adults. Scavengers will eat these animals who die from natural causes or injury, but there are no true predators for healthy gorillas.

Reproduction, Babies, and Lifespan

Females reach sexual maturity around the age of seven or eight years old. Their gestational period is approximately eight and a half months long. On average, they give birth to a single baby every four years or so. Males mature more slowly, and they attain maturity between 12 and 13 years. Upon reaching maturity, males leave the troop and form their own troop with adult females that they take from other bands during raids. The juveniles of the troop are all fathered by the one or two silverbacks that lead the group.

A baby gorilla is entirely helpless from birth to around three months old and spends much of that time being carried in its mother’s arms. They also possess the ability to fiercely cling to their mother’s chest or back, but they cannot care for themselves or walk during that time. A baby gorilla weighs only four to five pounds at birth.

Wild gorillas live anywhere between 20 and 40 years, while captive animals have been known to live well into their 40s. Until recently, the oldest known gorilla living in captivity was a female western lowland gorilla named Trudy. She died at the age of 63 in Little Rock Zoo in 2019. She was also believed to be the last captive gorilla in North America that was captured in the wild. As of 2021, a gorilla named Fatou is believed to be 64 years old. This makes Fatou the oldest gorilla in the world.

Population

All species are currently considered to be critically endangered, and their populations are all in decline. Only 4,000 eastern lowland gorillas and 880 mountain gorillas are estimated to be in the wild. Between both of those groups, only 2,600 individuals are mature adults. Approximately 300,000 western lowland gorillas are living, but they are experiencing a double-digit percentage population decline. Only 250 to 300 Cross River gorillas remain in a small region surrounding the Cross River.

Gorillas In the Zoo

These animals can be found in almost any major zoo. All gorillas in zoos in the United States are western lowland gorillas, and they were all born in captivity. None of these animals were captured in the wild. Both the Detroit Zoo and the Bronx Zoo are well-known for their gorillas.