Gorillas are the largest of the living
primateA primate is a member of the biological order Primates , the group that contains lemurs, lorisids, galagos, tarsiers, monkeys, and apes, with the last category including great apes. With the exception of humans, who inhabit every continent on Earth, most primates live in tropical or subtropical...
s. They are ground-dwelling and predominantly herbivorous. They inhabit the
forestA forest is an area with a high density of trees. There are many definitions of a forest, based on the various criteria. These plant communities presently cover approximately 9.4% of the Earth's surface in many different regions and function as habitats for organisms, hydrologic flow modulators,...
s of central
AfricaAfrica is the world's second-largest and second most-populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area. With a billion people in 61 territories, it accounts for about 14.8% of the...
. Gorillas are divided into two
speciesIn biology, a species is:* a taxonomic rank or* a unit at that rank ....
and (still under debate as of 2008) either four or five
subspeciesSubspecies in biological classification, is 1) a taxonomic rank subordinate to species, or 2) a taxonomic unit, a taxon in that rank...
. The
DNADeoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms and some viruses. The main role of DNA molecules is the long-term storage of information...
of gorillas is
98%–99% identical to that of a humanHuman evolutionary genetics studies how one human genome differs from the other, the evolutionary past that gave rise to it, and its current effects. Differences between genomes have anthropological, medical and forensic implications and applications...
, and they are the next closest living relatives to
humanHumans are bipedal primates belonging to the species Homo sapiens in Hominidae, the great ape family. They are the only surviving member of the genus Homo. Humans have a highly developed brain, capable of abstract reasoning, language, introspection, and problem solving...
s after the two
chimpanzeeChimpanzee, sometimes colloquially chimp, is the common name for the two extant species of ape in the genus Pan. The Congo River forms the boundary between the native habitat of the two species:...
species.
Gorillas live in tropical or subtropical forests. Although their range covers a small percentage of Africa, gorillas cover a wide range of elevations. The
Mountain GorillaThe Mountain Gorilla is one of the two subspecies of the Eastern Gorilla. There are two populations. One is found in the Virunga volcanic mountains of Central Africa, within 3 national parks: Mgahinga, in south-west Uganda; Volcanoes, in north-west Rwanda; and Virunga in the eastern Democratic...
inhabits the
Albertine RiftThe Albertine Rift montane forests are a tropical moist broadleaf forest ecoregion in the heart of tropical Africa. The high montane forests cover the western portions of Rwanda and Burundi, the eastern edge of the Democratic Republic of the Congo, and portions of western Uganda and Tanzania...
montane
cloud forestA cloud forest, also called a fog forest, is a generally tropical or subtropical evergreen montane moist forest characterized by a high incidence of low-level cloud cover, usually at the canopy level. Cloud forests often exhibit an abundance of mosses covering the ground and vegetation, in which...
s of the
Virunga VolcanoesThe Virunga Mountains are a chain of volcanoes in East Africa, along the northern border of Rwanda, the Democratic Republic of the Congo and Uganda. The mountain range is a branch of the Albertine Rift, a part of the Great Rift Valley. They are located between Lake Edward and Lake Kivu.The...
, ranging in altitude from 2225 to 4267 m (7300-14000 ft). Lowland Gorillas live in dense forests and lowland swamps and marshes as low as
sea levelMean sea level is the average height of the ocean's surface ; used as a standard in reckoning land elevation.- Measurement :...
.
Etymology
The American physician and missionary
Thomas Staughton SavageThomas Staughton Savage was an American Protestant clergyman, missionary, physician and naturalist.Born June 7, 1804 in Cromwell, Connecticut, died December 27, 1880 in Rinebeck, New York. First marriage to Susan A...
and naturalist
Jeffries WymanJeffries Wyman was an American naturalist and anatomist, born in Chelmsford, Massachusetts. Wyman died in Bethlehem, New Hampshire of a pulmonary hemorrhage.-Career:...
first described the
Western GorillaThe Western Gorilla is a great ape and the most populous species of the genus Gorilla.-Taxonomy:Nearly all of the individuals of this taxon belong to the Western Lowland Gorilla subspecies whose population is approximately 350,000 individuals...
(they called it
Troglodytes gorilla) in 1847 from specimens obtained in
LiberiaLiberia , officially the Republic of Liberia, is a country on the west coast of Africa, bordered by Sierra Leone, Guinea, Côte d'Ivoire, and the Atlantic Ocean. As of the 2008 Census, the nation is home to 3,476,608 people and covers ....
. The name was derived from the Greek word
Gorillai (a "tribe of hairy women") described by
Hanno the NavigatorHanno the Navigator was a Carthaginian explorer c. 500 BC, best known for his naval exploration of the African coast.- Etymology :...
, a Carthaginian navigator and possible visitor (circa 480 BC) to the area that later became
Sierra LeoneSierra Leone , officially the Republic of Sierra Leone, is a country in West Africa. It is bordered by Guinea in the north, Liberia in the southeast, and the Atlantic Ocean in the southwest. Sierra Leone covers a total area of and has a population estimated at 6.4 million...
.
Evolution and classification
The closest relatives of gorillas are chimpanzees and humans, from which gorillas diverged about 7 million years ago. Human genes differ only 1.6% on average from their corresponding gorilla genes in their sequence, but there is further difference in how many
copiesA copy number variation is a segment of DNA in which copy-number differences have been found by comparison of two or more genomes. The segment may range from one kilobase to several megabases in size. Humans ordinarily have two copies of each autosomal region, one per chromosome...
each gene has.
Until recently there was considered to be a single gorilla species, with three subspecies: the Western Lowland Gorilla, the Eastern Lowland Gorilla and the Mountain Gorilla. There is now agreement that there are two species with two subspecies each. More recently it has been claimed that a third subspecies exists in one of the species.
PrimatologistsPrimatology is the study of primates. It is a diverse discipline and primatologists can be found in departments of biology, anthropology, psychology and many others. It is a branch of Physical anthropology, which, in itself, studies the genus Homo, especially Homo sapiens...
continue to explore the relationships between various gorilla populations. The species and subspecies listed here are the ones upon which most scientists agree.
- Genus Gorilla
- Western Gorilla
The Western Gorilla is a great ape and the most populous species of the genus Gorilla.-Taxonomy:Nearly all of the individuals of this taxon belong to the Western Lowland Gorilla subspecies whose population is approximately 350,000 individuals...
(Gorilla gorilla)
- Western Lowland Gorilla
The Western Lowland Gorilla is a subspecies of the Western Gorilla that lives in montane, primary, and secondary forests and lowland swamps in Angola, Cameroon, Central African Republic, Congo, Democratic Republic of the Congo, Equatorial Guinea and Gabon. It is the gorilla usually found in zoos...
(Gorilla gorilla gorilla)
- Cross River Gorilla
The Cross River Gorilla is a subspecies of the Western Gorilla that can be found on the border between Nigeria and Cameroon, in both tropical and subtropical moist broadleaf forests which are also home to the Nigeria-Cameroon Chimpanzee, another subspecies of great ape...
(Gorilla gorilla diehli)
- Eastern Gorilla
The Eastern Gorilla is a species of the genus Gorilla and the largest living primate. At present, the species is subdivided into two subspecies. The Eastern Lowland Gorilla is the most populous, at about 16,000 individuals. The Mountain Gorilla has only about 700 individuals...
(Gorilla beringei)
- Mountain Gorilla
The Mountain Gorilla is one of the two subspecies of the Eastern Gorilla. There are two populations. One is found in the Virunga volcanic mountains of Central Africa, within 3 national parks: Mgahinga, in south-west Uganda; Volcanoes, in north-west Rwanda; and Virunga in the eastern Democratic...
(Gorilla beringei beringei)
- Eastern Lowland Gorilla
The Eastern Lowland Gorilla is a subspecies of Eastern Gorilla that is now only found in the forests of eastern Democratic Republic of the Congo....
(Gorilla beringei graueri)
The proposed third subspecies of
Gorilla beringei, which has not yet received a
trinomenIn zoological nomenclature, a trinomen, or trinominal name, refers to the name of a subspecies.A trinomen is a name consisting of three names: generic name, specific name and subspecific name. All three names are typeset in italics, and only the generic name is capitalised...
, is the
Bwindi populationThe Bwindi gorilla, a population of the Mountain Gorilla , is found in the rain forests of the Bwindi Impenetrable Forest, and comprises about half the world's endangered population of about 600 Mountain Gorillas...
of the Mountain Gorilla, sometimes called the Bwindi Gorilla.
Physical characteristics
Gorillas move around by
knuckle-walkingKnuckle-walking is a form of quadrupedal walking in which the forelimbs hold the fingers in a partially flexed posture that allows body weight to press down on the ground through the knuckles....
. Adult males range in height from 165-175 cm (5 ft 5 in – 5 ft 9 in), and in weight from 140–204.5 kg (310–450 lb). Adult females are often half the size of a silverback, averaging about 140 cm (4 ft 7 in) tall and 100 kg (220 lb). Occasionally, a silverback of over 183 cm (6 ft) and 225 kg (500 lb) has been recorded in the wild. However, obese gorillas in captivity have reached a weight of 270 kg (600 lb). Gorillas have a facial structure which is described as mandibular prognathism, that is, their
mandibleThe mandible or inferior maxillary bone forms the lower jaw and holds the lower teeth in place. It also refers to both the upper and lower sections of the beaks of birds; in this case the "lower mandible" corresponds to the mandible of humans while the "upper mandible" is functionally equivalent...
protrudes farther out than the
maxillaThe maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes , the maxilla is sometimes called "upper maxilla", with the mandible being the "lower maxilla"...
.
The Eastern Gorilla is more darkly colored than the Western Gorilla, with the Mountain Gorilla being the darkest of all. The Mountain Gorilla also has the thickest hair. The Western Lowland Gorilla can be brown or grayish with a reddish forehead. In addition, gorillas that live in lowland forests are more slender and agile than the more bulky Mountain Gorilla.
Almost all gorillas share the same
blood typeA blood type is a classification of blood based on the presence or absence of inherited antigenic substances on the surface of red blood cells...
(B) and, like humans, have individual finger prints.
Group life
A
silverback is an adult male gorilla, typically more than 12 years of age and named for the distinctive patch of silver hair on his back. A silverback gorilla has large canine teeth that come with maturity.
Blackbacks are sexually mature males of up to 11 years of age.
Silverbacks are the strong, dominant troop leaders. Each typically leads a troop (
group sizeMany animals, including humans, tend to live in groups, herds, flocks, bands, packs, shoals, or colonies of conspecific individuals. The size of these groups, as expressed by the number of participant individuals, is an important aspect of their social environment...
ranges from 5 to 30) and is in the center 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. Blackbacks may serve as backup protection.
Males will slowly begin to leave their original troop when they are about 11 years old, traveling alone or with a group of other males for 2–5 years before being able to attract females to form a new group and start breeding. While infant gorillas normally stay with their mother for 3–4 years, silverbacks will care for weaned young orphans, though never to the extent of carrying the little gorillas.
If challenged by a younger or even by an outsider male, a silverback will scream, beat his chest, break branches, bare his teeth, then charge forward. Sometimes a younger male in the group can take over leadership from an old male. If the leader is killed by disease, accident, fighting or poachers, the group will split up, as the animals disperse to look for a new protective male. Occasionally, a group may be taken over in its entirety by another male. There is a strong risk that the new male will kill the infants of the dead silverback.
Food and foraging
Gorillas are
herbivoreA herbivore is an animal that is adapted to eat plants and not meat.Herbivory is a form of predation in which an organism consumes principally autotrophs such as plants, algae and photosynthesizing bacteria....
s, eating fruits, leaves, and shoots. Further they are classified as foliovores. Much like other animals that feed on plants and shoots, they sometimes ingest small insects as well. Gorillas spend most of the day eating. Their large
sagittal crestA sagittal crest is a ridge of bone running lengthwise along the midline of the top of the skull of many mammalian and reptilian skulls, among others. The presence of this ridge of bone indicates that there are exceptionally strong jaw muscles. The sagittal crest serves primarily for attachment...
and long canines allow them to crush hard plants like
bambooThe bamboos are a group of woody perennial evergreen plants in the true grass family Poaceae, subfamily Bambusoideae, tribe Bambuseae. Some are giant bamboos, the largest members of the grass family. Bamboos are the fastest growing woody plants in the world...
. Lowland gorillas feed mainly on fruit while Mountain gorillas feed mostly on herbs, stems and roots.
Reproduction and lifespan
GestationGestation is the carrying of an embryo or fetus inside a female viviparous animal. Mammals duringpregnancy can have one or more gestations at the same time ....
is 8½ months. There are typically 3 to 4 years between births. Infants stay with their mothers for 3–4 years. Females mature at 10–12 years (earlier in captivity); males at 11–13 years. Lifespan is between 30–50 years, although there have been exceptions. For example the
Dallas Zoo'sDallas Zoo is a zoo located south of downtown Dallas in the Oak Cliff area of Dallas, Texas . The zoo was originally founded in 1888 and now covers , making it the largest zoological park in Texas . The Dallas Zoo is home to 406 species and 1,800 animals...
JennyJenny was a Western lowland gorilla who resided at the Dallas Zoo in Dallas, Texas. Jenny was the world's oldest gorilla in captivity at the time of her death in 2008 at the age of 55. Jenny was confirmed to be the oldest living gorilla in the world by the International Species Information System...
lived to the age of 55.
Recently, gorillas have been observed engaging in face-to-face sex, a trait that was once considered unique to humans and the
BonoboThe Bonobo , Pan paniscus, until recently called the Pygmy Chimpanzee and less often, the Dwarf or Gracile Chimpanzee, is a great ape and one of the two species making up the genus Pan. The other species in genus Pan is Pan troglodytes, or the Common Chimpanzee...
.
Intelligence
Gorillas are closely related to humans and are considered highly intelligent. A few individuals in captivity, such as
KokoKoko is a lowland gorilla who, according to Francine 'Penny' Patterson, is able to understand more than 1,000 signs based on American Sign Language, and understand approximately 2,000 words of spoken English...
, have been taught a subset of
sign languageA sign language is a language which, instead of acoustically conveyed sound patterns, uses visually transmitted sign patterns to convey meaning—simultaneously combining hand shapes, orientation and movement of the hands, arms or body, and facial expressions to fluidly express a speaker's...
(see
animal languageAnimal language is the modeling of human language in non human animal systems. While the term is widely used, most researchers agree that animal languages are not as complex or expressive as human language....
for a discussion).
Tool use
The following observations were made by a team led by Thomas Breuer of the Wildlife Conservation Society in September 2005. Gorillas are now known to use
toolA broad definition of a tool is an entity used to interface between two or more domains that facilitates more effective action of one domain upon the other. The most basic tools are simple machines. For example, a crowbar simply functions as a lever. The further out from the pivot point, the more...
s in the wild. A female gorilla in the Nouabalé-Ndoki National Park in the Republic of Congo was recorded using a stick as if to gauge the depth of water whilst crossing a
swampA swamp is a wetland featuring temporary or permanent inundation of large areas of land by shallow bodies of water. A swamp generally has a substantial number of hammocks, or dry-land protrusions, covered by aquatic vegetation, or vegetation that tolerates periodical inundation. The two main types...
. A second female was seen using a tree stump as a bridge and also as a support whilst fishing in the swamp. This means that all of the great apes are now known to use tools.
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 forty years previously
chimpanzeeChimpanzee, sometimes colloquially chimp, is the common name for the two extant species of ape in the genus Pan. The Congo River forms the boundary between the native habitat of the two species:...
s had been seen using tools in the wild, famously 'fishing' for termites. Great
apeAn ape is any member of the Hominoidea superfamily of primates. Due to its ambiguous nature, the term ape is less suitable as a means of describing taxonomic relationships....
s are endowed with a semi-precision grip, and certainly have been able to use both simple tools and even weapons, by improvising a club from a convenient fallen branch.
Studies
The word "gorilla" comes from the history of
Hanno the NavigatorHanno the Navigator was a Carthaginian explorer c. 500 BC, best known for his naval exploration of the African coast.- Etymology :...
, a Carthaginian explorer on an expedition on the west African coast. They encountered "a savage people, the greater part of whom were women, whose bodies were hairy, and whom our interpreters called Gorillae". The word was then later used as the species name, though it is unknown whether what these ancient Carthaginians encountered were truly gorillas, another species of ape or monkeys, or humans.
American physician and missionary Thomas Staughton Savage obtained the first specimens (the skull and other bones) during his time in
LiberiaLiberia , officially the Republic of Liberia, is a country on the west coast of Africa, bordered by Sierra Leone, Guinea, Côte d'Ivoire, and the Atlantic Ocean. As of the 2008 Census, the nation is home to 3,476,608 people and covers ....
in Africa. The first scientific description of gorillas dates back to the publication of by Savage and the naturalist
Jeffries WymanJeffries Wyman was an American naturalist and anatomist, born in Chelmsford, Massachusetts. Wyman died in Bethlehem, New Hampshire of a pulmonary hemorrhage.-Career:...
in 1847 in
Proceedings of the Boston Society of Natural History, where
Troglodytes gorilla is described, now known as the
Western GorillaThe Western Gorilla is a great ape and the most populous species of the genus Gorilla.-Taxonomy:Nearly all of the individuals of this taxon belong to the Western Lowland Gorilla subspecies whose population is approximately 350,000 individuals...
. Other species of gorilla are described in the next couple of years.
Explorer
Paul du ChailluPaul Belloni du Chaillu was a French-American traveler and anthropologist. He became famous in the 1860s as the first modern outsider to confirm the existence of gorillas and the Pygmy people of central Africa. He later researched the prehistory of Scandinavia.-Early life:His date and place of...
was the first westerner to see a live gorilla during his travel through western equatorial Africa from 1856 to 1859. He brought dead specimens to England in 1861.
The first systematic study was not conducted until the 1920s, when
Carl AkeleyHe was born in Clarendon, New York, and grew up on a farm, attending school for only three years. He learned taxidermy from David Bruce in Brockport, New York, and then entered an apprenticeship in taxidermy at Ward's Natural Science Establishment in Rochester, New York...
of the
American Museum of Natural HistoryThe American Museum of Natural History , located on the Upper West Side, Manhattan, New York, USA, is one of the largest and most celebrated museums in the world...
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 famous mystery writer, and her husband. 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 YerkesRobert Mearns Yerkes was an American psychologist, ethologist, and primatologist best known for his work in intelligence testing and in the field of comparative psychology. Yerkes was a pioneer in the study both of human and primate intelligence and of the social behavior of gorillas and...
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 WWII,
George SchallerGeorge Beals Schaller is an American mammalogist, naturalist, conservationist and author. Schaller is recognized by many as the world's preeminent field biologist, studying wildlife throughout Africa, Asia and South America. Born in Berlin, Schaller grew up in Germany, but moved to Missouri as a...
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 LeakeyLouis Seymour Bazett Leakey was a Kenyan archaeologist and naturalist whose work was important in establishing human evolutionary development in Africa. He also played a major role in creating organizations for future research in Africa and for protecting wildlife there...
and the
National Geographic,
Dian FosseyDian Fossey was an American zoologist who undertook an extensive study of gorilla groups over a period of 18 years. She observed them daily for years in the mountain forests of Rwanda, initially encouraged to work there by famous paleontologist Louis Leakey...
conducted a much longer and more comprehensive study of the Mountain Gorilla. It was not until she published her work that many misconceptions and myths about gorillas were finally disproved, including the myth that gorillas are violent.
Endangerment
Both species of gorilla are
endangeredAn endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters. Also it could mean that due to deforestation there may be a lack of food and/or water...
, and have been subject to intense
poachingPoaching is the illegal hunting, fishing, trapping, or eating of wild plants or animals contrary to local and international conservation and wildlife management laws...
for a long time. Threats to gorilla survival include
habitat destructionHabitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms which previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity mainly for the purpose...
and the
bushmeatBushmeat is the term commonly used for meat of terrestrial wild animals, killed for subsistence or commercial purposes throughout the humid tropics of the Americas, Asia, and Africa. However, originally the term was usually used to describe the hunting of wild animals in West and Central Africa...
trade. In 2004 a population of several hundred gorillas in the
Odzala National ParkOdzala National Park is a national park in the Cuvette-Ouest Region of Republic of the Congo. Founded in 1935, the park now covers 13,600 Km2. It is known as "one of the most important strongholds for forest elephant and western gorilla conservation remaining in Central Africa".-External...
, Republic of Congo was essentially wiped out by the Ebola virus. A 2006 study published in Science concluded
that more than 5,000 gorillas may have died in recent outbreaks of the Ebola virus in central Africa. The researchers
indicated that in conjunction with commercial hunting of these apes, the virus creates "a recipe for rapid ecological
extinctionIn biology and ecology, extinction is the end of an organism or group of taxa. The moment of extinction is generally considered to be the death of the last individual of that species...
." Conservation efforts include the
Great Ape Survival ProjectThe Great Apes Survival Project , established in 2001, aims to conserve the great apes and their habitat — primarily forested tropical ecosystems that provide important services to humanity, through pro-poor conservation and sustainable development strategies.GRASP is a UNEP and UNESCO-led World...
, a partnership between the
United Nations Environment ProgrammeThe UN Environment Programme coordinates United Nations environmental activities, assisting developing countries in implementing environmentally sound policies and encourages sustainable development through sound environmental practices...
and the
United Nations Educational, Scientific and Cultural OrganizationThe United Nations Educational, Scientific and Cultural Organization is a specialized agency of the United Nations established on 16 November 1945...
, and also an international treaty, the
Agreement on the Conservation of Gorillas and Their HabitatsThe Agreement on the Conservation of Gorillas and Their Habitats, also known as the Gorilla Agreement, is an international treaty that binds the Parties to conserve gorillas in their territories. It was concluded 2007 under the auspices of the Convention on Migratory Species of Wild Animals , also...
, concluded under UNEP-administered
Convention on Migratory SpeciesThe Convention on the Conservation of Migratory Species of Wild Animals aims to conserve terrestrial, marine and avian migratory species throughout their range...
. The
Gorilla AgreementThe Agreement on the Conservation of Gorillas and Their Habitats, also known as the Gorilla Agreement, is an international treaty that binds the Parties to conserve gorillas in their territories. It was concluded 2007 under the auspices of the Convention on Migratory Species of Wild Animals , also...
is the first legally binding instrument exclusively targeting Gorilla conservation and came into effect on 1 June 2008.
Cultural references
Since they came to the attention of western society in the 1860s, gorillas have been a recurring element of many aspects of popular culture and media. For example, gorillas have featured prominently in monstrous fantasy films such as
King KongKing Kong is a fictional movie monster that has appeared in several films since 1933. These include the groundbreaking 1933 film King Kong, the film remakes of 1976 and 2005, as well as various sequels...
, and pulp fiction such as the stories of
TarzanTarzan is a fictional character, an archetypal feral child raised in the African jungle by fictional great apes, who later returns to civilization only to largely reject it and return to the wild as a heroic adventurer...
and
Conan the BarbarianConan the Barbarian is a fictional character in books, comics and movies. He is a hero, a well known and iconic figure in American fantasy, and the most famous barbarian in fiction.Conan is often associated with the fantasy subgenre of sword-and-sorcery and heroic fantasy...
have featured gorillas as physical opponents to the titular protagonists.
External links