Gorilla

Gorilla

Overview
Gorillas are the largest extant species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of primate
Primate
A primate is a mammal of the order Primates , which contains prosimians and simians. Primates arose from ancestors that lived in the trees of tropical forests; many primate characteristics represent adaptations to life in this challenging three-dimensional environment...

s. They are ground-dwelling, predominantly herbivorous ape
Ape
Apes are Old World anthropoid mammals, more specifically a clade of tailless catarrhine primates, belonging to the biological superfamily Hominoidea. The apes are native to Africa and South-east Asia, although in relatively recent times humans have spread all over the world...

s that inhabit the forest
Forest
A forest, also referred to as a wood or the woods, is an area with a high density of trees. As with cities, depending where you are in the world, what is considered a forest may vary significantly in size and have various classification according to how and what of the forest is composed...

s of central Africa
Africa
Africa 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...

. Gorillas are divided into two species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 and either four or five subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...

. The DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...

 of gorillas is highly similar to that of a human
Human evolutionary genetics
Human 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...

, from 95–99% depending on what is counted, and they are the next closest living relatives to human
Human
Humans are the only living species in the Homo genus...

s after the bonobo
Bonobo
The bonobo , Pan paniscus, previously 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...

 and chimpanzee
Chimpanzee
Chimpanzee, 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:...

.

Gorillas' natural habitats cover tropical or subtropical forests in Africa
Africa
Africa 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...

.
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Encyclopedia
Gorillas are the largest extant species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of primate
Primate
A primate is a mammal of the order Primates , which contains prosimians and simians. Primates arose from ancestors that lived in the trees of tropical forests; many primate characteristics represent adaptations to life in this challenging three-dimensional environment...

s. They are ground-dwelling, predominantly herbivorous ape
Ape
Apes are Old World anthropoid mammals, more specifically a clade of tailless catarrhine primates, belonging to the biological superfamily Hominoidea. The apes are native to Africa and South-east Asia, although in relatively recent times humans have spread all over the world...

s that inhabit the forest
Forest
A forest, also referred to as a wood or the woods, is an area with a high density of trees. As with cities, depending where you are in the world, what is considered a forest may vary significantly in size and have various classification according to how and what of the forest is composed...

s of central Africa
Africa
Africa 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...

. Gorillas are divided into two species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 and either four or five subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...

. The DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...

 of gorillas is highly similar to that of a human
Human evolutionary genetics
Human 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...

, from 95–99% depending on what is counted, and they are the next closest living relatives to human
Human
Humans are the only living species in the Homo genus...

s after the bonobo
Bonobo
The bonobo , Pan paniscus, previously 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...

 and chimpanzee
Chimpanzee
Chimpanzee, 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:...

.

Gorillas' natural habitats cover tropical or subtropical forests in Africa
Africa
Africa 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...

. Although their range covers a small percentage of Africa, gorillas cover a wide range of elevations. The mountain gorilla
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 three National Parks: Mgahinga, in south-west Uganda; Volcanoes, in north-west Rwanda; and Virunga in the eastern Democratic...

 inhabits the Albertine Rift
Albertine Rift montane forests
The Albertine Rift montane forests ecoregion, of the Tropical moist broadleaf forest Biome, are in the heart of Afromontane tropical Africa.-Location and description:...

 montane cloud forest
Cloud forest
A cloud forest, also called a fog forest, is a generally tropical or subtropical evergreen montane moist forest characterized by a persistent, frequent or seasonal low-level cloud cover, usually at the canopy level. Cloud forests often exhibit an abundance of mosses covering the ground and...

s of the Virunga Volcanoes
Virunga Mountains
The 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...

, ranging in altitude from 2200–4300 m (7,217.8–14,107.6 ft). Lowland gorillas live in dense forests and lowland swamps and marshes as low as sea level
Sea level
Mean sea level is a measure of the average height of the ocean's surface ; used as a standard in reckoning land elevation...

, with western lowland 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...

s living in Central West African countries and eastern lowland gorilla
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...

s living in the Democratic Republic of the Congo
Democratic Republic of the Congo
The Democratic Republic of the Congo is a state located in Central Africa. It is the second largest country in Africa by area and the eleventh largest in the world...

 near its border with Rwanda
Rwanda
Rwanda or , officially the Republic of Rwanda , is a country in central and eastern Africa with a population of approximately 11.4 million . Rwanda is located a few degrees south of the Equator, and is bordered by Uganda, Tanzania, Burundi and the Democratic Republic of the Congo...

.

Etymology


The American physician and missionary Thomas Staughton Savage
Thomas S. Savage
Thomas 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 Wyman
Jeffries Wyman
Jeffries 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 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 95,000 individuals...

 (they called it Troglodytes gorilla) in 1847 from specimens obtained in Liberia
Liberia
Liberia , officially the Republic of Liberia, is a country in West Africa. It is bordered by Sierra Leone on the west, Guinea on the north and Côte d'Ivoire on the east. Liberia's coastline is composed of mostly mangrove forests while the more sparsely populated inland consists of forests that open...

. The name was derived from the Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 word "Γόριλλαι" (Gorillai), a "tribe of hairy women" described by Hanno the Navigator
Hanno the Navigator
Hanno the Navigator was a Carthaginian explorer c. 500 BC, best known for his naval exploration of the African coast...

, a Carthaginian
Carthage
Carthage , implying it was a 'new Tyre') is a major urban centre that has existed for nearly 3,000 years on the Gulf of Tunis, developing from a Phoenician colony of the 1st millennium BC...

 navigator and possible visitor (circa 480 BC) to the area that later became Sierra Leone
Sierra Leone
Sierra Leone , officially the Republic of Sierra Leone, is a country in West Africa. It is bordered by Guinea to the north and east, Liberia to the southeast, and the Atlantic Ocean to the west and southwest. Sierra Leone covers a total area of and has an estimated population between 5.4 and 6.4...

.

Evolution and classification


The closest relatives of gorillas are chimpanzees and humans, all of the Hominidae having diverged from a common ancestor 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 copies
Gene copy number
Copy-number variations —a form of structural variation—are alterations of the DNA of a genome that results in the cell having an abnormal number of copies of one or more sections of the DNA. CNVs correspond to relatively large regions of the genome that have been deleted or duplicated on certain...

 each gene has. Richard Dawkins in his book The Ancestor’s Tale (Boston: Houghton Mifflin, 2004) proposes that gorillas are descended from Australopithecus Robustus (parnthropus) type species. For instance Paranthropus aethiopicus has characteristic gorilla-like crests on its skull (see Homininae
Homininae
Homininae is a subfamily of Hominidae, which includes humans, gorillas and chimpanzees, and some extinct relatives; it comprises all those hominids, such as Australopithecus, that arose after the split from orangutans . Our family tree, which has 3 main branches leading to chimpanzees, humans and...

). In other words the ancestors of gorillas are Paranthropus. 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. The separate species and subspecies developed from a single type of gorilla during the Ice Age
Ice age
An ice age or, more precisely, glacial age, is a generic geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental ice sheets, polar ice sheets and alpine glaciers...

, when their forest habitats shrank and became isolated from each other.

Primatologists
Primatology
Primatology is the scientific study of primates. It is a diverse discipline and researchers can be found in academic departments of anatomy, anthropology, biology, medicine, psychology, veterinary sciences and zoology, as well as in animal sanctuaries, biomedical research facilities, museums and zoos...

 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
      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 95,000 individuals...

       (Gorilla gorilla)
      • Western lowland 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
        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
      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 5,000 individuals. The mountain gorilla has only about 700 individuals...

       (Gorilla beringei)
      • Mountain gorilla
        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 three National Parks: Mgahinga, in south-west Uganda; Volcanoes, in north-west Rwanda; and Virunga in the eastern Democratic...

         (Gorilla beringei beringei)
      • Eastern lowland gorilla
        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 trinomen
Trinomen
In 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. The first two parts alone form the binomen or species name. All three names are typeset in italics, and...

, is the Bwindi population of the mountain gorilla, sometimes called the Bwindi gorilla.

Some variations that distinguish the classifications of gorilla include varying density, size, hair color, length, culture, and facial widths. There are now thought to be over 100,000 western lowland gorillas in the wild, with 4,000 in zoos; eastern lowland gorillas have a population of 4,000 in the wild and 24 in zoos. Mountain gorillas are the most severely endangered, with an estimated population of about 620 left in the wild and none in zoos.

Physical characteristics



Gorillas move around by knuckle-walking
Knuckle-walking
Knuckle-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....

, although they sometimes walk bipedally for short distances while carrying food or in defensive situations. Adult males, also called silverbacks, range in height 1.65 –, and in weight 140–200 kg (308.6–440.9 lb). Adult females are often half the size of a silverback, averaging about 1.4 metre tall and 100 kg (220 lb). Occasionally, a silverback of over 1.8 metre and 230 kg (507.1 lb) has been recorded in the wild. Obese gorillas in captivity have reached a weight of 270 kg (595.2 lb). Gorillas have a facial structure which is described as mandibular prognathism, that is, their mandible
Mandible
The mandible pronunciation or inferior maxillary bone forms the lower jaw and holds the lower teeth in place...

 protrudes farther out than the maxilla
Maxilla
The 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 (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...

. Adult males also have a prominent sagittal crest
Sagittal crest
A 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 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. The eastern gorilla also has a longer face and broader chest than the western gorilla.

Almost all gorillas share the same blood type
Blood type
A blood type is a classification of blood based on the presence or absence of inherited antigenic substances on the surface of red blood cells . These antigens may be proteins, carbohydrates, glycoproteins, or glycolipids, depending on the blood group system...

 (B) and, like humans, have individual finger prints.
Their eye color is dark brown, framed by a black ring around the iris. Similar to humans, the leading cause of death in gorillas is cardiovascular disease.

Behavior and ecology



Range and habitat


Gorillas have a patchy distribution. The range of the two species is separated by the Congo river
Congo River
The Congo River is a river in Africa, and is the deepest river in the world, with measured depths in excess of . It is the second largest river in the world by volume of water discharged, though it has only one-fifth the volume of the world's largest river, the Amazon...

 and its tributarie
Tributary
A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...

s. 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
Montane
In biogeography, montane is the highland area located below the subalpine zone. Montane regions generally have cooler temperatures and often have higher rainfall than the adjacent lowland regions, and are frequently home to distinct communities of plants and animals.The term "montane" means "of the...

 forests to swamps. Eastern gorilla live in montane and submontane forests ranging 650–4000 m (2132-13,123 ft). Mountain gorillas live in the montane forests at the higher ends of the elevation range while eastern lowland gorillas live in submotane forests at the lower ends of the elevation range. In addition, eastern lowland gorillas live in montane bamboo forests as well as lowland forests ranging from 600–3308 m (1969-10,853 ft) in elevation. Western gorillas live in both lowland swamp forests and montane forests and live in elevations ranging from sea level to 1600 m (5249 ft). Western lowland gorillas live in swamp and lowland forests ranging up to 1600 m (5249 ft) and Cross River gorillas live in low-lying and submontane forests ranging 150–1600 m (492–5249 ft).

Food and foraging


Gorillas have synchronized activities. During the day they alternate between rest periods and travel or feeding periods. There are dietary differences between and within the species. Mountain gorillas mostly mostly foliage such as leaves, stems, pith, and shoots of terrestrial herbaceous vegetation. High quality, high protein, low fiber, and low tannin
Tannin
A tannin is an astringent, bitter plant polyphenolic compound that binds to and precipitates proteins and various other organic compounds including amino acids and alkaloids.The term tannin refers to the use of...

 foods from certain species are preferred and fruit makes up a very small part of their diet. Bamboo
Bamboo
Bamboo is a group of perennial evergreens in the true grass family Poaceae, subfamily Bambusoideae, tribe Bambuseae. Giant bamboos are the largest members of the grass family....

 is also a favored food item and gorillas will spend much time digging to unearth the tender shoots. Little competition exists between mountain gorilla groups for resources since they rely on food that is readily available and easily accessed. They have small home ranges that range from 3–15 km2 (1.16–5.79 mi2), and they move only 500 m (0.311 mi) or less on an average day. Despite eating a few species in each habitat, mountain gorillas have a flexible diet and can occupy a wide variety of habitats in their range.

Lowland gorillas have a more diverse diet. The diet of the eastern lowland gorilla varies seasonally. Leaves and pith are staples of their diet but they also eat fruits when they are available and fruits can make up as much as 25% of their diet. Since fruit is relatively scarce, gorillas must travel farther each day and have home ranges that vary from 2.7–6.5 km2 (1.04 to 2.51 mi2) with day ranges 154–2280 m (0.096–1.42 mi). Eastern lowland gorillas will also eat insects, preferably ants. Western lowland gorillas do not have much access to high quality terrestrial herbs, although some areas in their range are rich in aquatic herbs. These gorillas depend on fruits more than the others and they are more dispersed across their range. Western lowland gorillas travel the farthest of the gorillas and have the largest home ranges. They travel 1105 m (0.687 mi) per day on average and have home ranges 7–14 km2 (2.70–5.41 mi2). Termites and ants also are a staple of the western lowland gorilla’s diet.

Gorillas rarely drink water "because they consume succulent vegetation that is almost half water as well as morning dew", although both mountain and lowland gorillas have been observed drinking.

One possible predator of gorillas is the leopard
Leopard
The leopard , Panthera pardus, is a member of the Felidae family and the smallest of the four "big cats" in the genus Panthera, the other three being the tiger, lion, and jaguar. The leopard was once distributed across eastern and southern Asia and Africa, from Siberia to South Africa, but its...

. Gorilla remains have been found in leopard scat but it is possible that this may be the result of scavenging. When the group is attacked by humans, leopards, or other gorillas, an individual silverback will protect the group, even at the cost of his own life. George Schaller reported that a silverback gorilla and a leopard were both found dead from mutually inflicted wounds.

Social structure



Gorillas live in groups called troops. Troops tend to be made of one adult male or silverback, multiple adult females and their offspring. However, multi-male troops also exist. Silverbacks are typically more than 12 years of age and named for the distinctive patch of silver hair on their back which comes with maturity. They also have large canine teeth which also come with maturity. Both males and females tend to emigrate from their natal groups. For mountain gorillas, females disperse from their natal troops more than males. Mountain gorillas and western lowland gorillas also commonly transfer to second new groups. Mature males tend to also leave their groups and establish their own troops by attracting emigrating females. However, male mountain gorillas sometimes stay in their natal troops and become subordinate to the silverback. If the silverback dies, these males may be able to become dominant or mate with the females. This behavior has not been observed in eastern lowland gorillas. In a single male group, when the silverback dies, the females and their offspring disperse and find a new troop. Without a silverback to protect them, the infants will likely fall victim to infanticide
Infanticide (zoology)
In animals, infanticide involves the killing of young offspring by a mature animal of its own species, and is studied in zoology, specifically in the field of ethology. Ovicide is the analogous destruction of eggs. Although human infanticide has been widely studied, the practice has been observed...

. Joining a new group is likely to be a tactic against this. However while gorilla troops usually disband after the silverback dies, female eastern lowlands gorillas and their offspring have been recorded staying together until a new silverback transfers into the group. This likely serves as protection from leopards. All male troops have also been recorded.

The silverback is 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. Younger males subordinate to the silverback, known as blackbacks, may serve as backup protection. Blackbacks are aged between 8 and 12 years of age and lack the silver back hair. The bond a silverback has with his females forms the core of gorilla social life. Bonds between them are maintained by grooming and close proximity. Having strong relationships with males is important for females as males give them mating opportunities and protection from predators and infanticidal outside males. However aggressive behaviors between males and females are common although they rarely lead to serious injury. Relationships between females may vary. Maternally related females in a troop associate closely and tend to have friendly interactions. Otherwise, females usually have little friendly interactions and commonly act aggressive towards each other. Aggressive interactions between females tend to be centered around social access to males with males intervening in fights between females. Male gorillas have weak social bonds, particularly in multi-male groups with apparent dominance hierarchies and strong competition for mates. However, males in all-male groups tend to have friendly interactions and socialize through play, grooming and close proximity, and occasionally they even engage in homosexual interactions.

Nesting



Gorillas construct nests for daytime and night use. Day nests tend to be simple aggregations of branches and leaves on the ground while night nests are more elaborate constructions in trees. The nests may be 2 to 5 ft (0.6096 to 1.5 m) in diameter and are constructed by individuals. The young nest with the mother but construct nests after three years of age, initially close to that of their mother. Gorilla nests are distributed arbitrarily and use of tree species for site and construction appears to be opportunistic. Nest building by great apes is now considered to be not just animal architecture but as an important instance of tool use.

Reproduction and parenting



A female’s first ovulatory cycle occurs when she is six years of age and is followed by a two year long period of adolescent infertility. The estrous cycle last 30–33 days with outward ovulation signs subtle compared to that of chimpanzees. The gestation period lasts 8.5 months. 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 incite copulation by pursing their lips and slowly approaching a male while establishing prolonged eye contact. If the male does not respond, then she will try to attract his attention by reaching towards him or slapping the ground. In multi-male groups, solicitation indicates female preference. However females can be coerced to mate with multiple males. Males incite copulation by approaching a female and displaying at her or touching her and giving a "train grunt". Recently, gorillas have been observed engaging in face-to-face sex, a trait that was once considered unique to humans and the bonobo
Bonobo
The bonobo , Pan paniscus, previously 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...

.

Gorilla infants are vulnerable and dependant and thus mothers, their primary caregivers, are important to their survival. Gorilla mothers invest years caring for their offspring. Male gorillas are not active in caring for the young. However they do play a role in socializing them as they will associate with older infants and juveniles. The silverback has a largely supportive relationship with the infants in his troop. He will shield them from intragroup aggression. Infants remain in contact with their mothers for the first five months and mothers stay near the silverback for protection. Infants will suckle at least once per hour and will sleep with their mothers in the same nest. Infants begin to break contact with their mothers after five months but only for brief period each time. By 12 months, infants venture up to five meters (16.4 ft) from their mothers. At around 18–21 months, the distance between mother and offspring increases and they regularly spend time away from each other. In addition, nursing decreases to once every two hours. Infants spend only half of their time with their mothers by 30 months. Gorillas enter their juvenile period at their third year and this lasts until their sixth year. At this time, gorillas are weaned and they sleep in a separate nest from their mothers. After their offspring are weaned, females begin to ovulate and soon become pregnant again. Conflicts in weaning between mother and offspring is minimized as the young has many play partners including the silverback. 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's
Dallas Zoo
Dallas Zoo is a zoo located south of downtown Dallas, Texas in Marsalis Park. Established in 1888, it is the oldest and largest zoological park in Texas and is managed by the non-profit Dallas Zoological Society. The zoo is home to 1,800 animals representing 406 species...

 Jenny
Jenny (gorilla)
Jenny 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.

Communication


Twenty-five distinct vocalization
Animal communication
Animal communication is any behavior on the part of one animal that has an effect on the current or future behaviour of another animal. The study of animal communication, is sometimes called Zoosemiotics has played an important part in the...

s are recognized, many of which are used primarily for group communication within dense vegetation. Sounds classified as grunts and barks are heard most frequently while traveling, and indicate the whereabouts of individual group members. They may also be used during social interactions when discipline is required. Screams and roars signal alarm or warning, and are produced most often by silverbacks. Deep, rumbling belches suggest contentment and are heard frequently during feeding and resting periods. They are the most common form of intragroup communication. Severe aggression
Aggression
In psychology, as well as other social and behavioral sciences, aggression refers to behavior between members of the same species that is intended to cause humiliation, pain, or harm. Ferguson and Beaver defined aggressive behavior as "Behavior which is intended to increase the social dominance of...

 is rare in stable groups, but when two mountain gorilla groups meet, the two silverbacks can sometimes engage in a fight to the death, using their canines to cause deep, gaping injuries. The entire sequence has nine steps: (1) progressively quickening hooting, (2) symbolic feeding, (3) rising bipedally, (4) throwing vegetation, (5) chest-beating with cupped hands, (6) one leg kick, (7) sideways running, two-legged to four-legged, (8) slapping and tearing vegetation, and (9) thumping the ground with palms to end display.

Intelligence


Gorillas are considered highly intelligent. A few individuals in captivity, such as Koko
Koko (gorilla)
Koko is a female western 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 language
Sign language
A 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 language
Animal language
Animal language is the modeling of human language in non human animal systems. While the term is widely used, researchers agree that animal languages are not as complex or expressive as human language....

 for a discussion). Like the other great apes, gorillas can laugh, grieve, have "rich emotional lives," develop strong family bonds, can make and use tools, and can think about the past and future. Some researchers believe that gorillas have spiritual feelings or religious sentiments. Gorillas have been shown to have cultures in different areas revolving around different methods of food preparation, and gorillas will show individual color preferences
Color preferences
In the psychology of color, color preferences are the tendency for an individual or a group to prefer some colors over others, including a favorite color.-Introduction:...

.

Tool use



The following observations were made by a team led by Thomas Breuer of the Wildlife Conservation Society
Wildlife Conservation Society
The Wildlife Conservation Society based at the Bronx Zoo was founded in 1895 as the New York Zoological Society and currently manages some of wild places around the world, with over 500 field conservation projects in 60 countries, and 200 scientists on staff...

 in September 2005. Gorillas are now known to use tool
Tool
A tool is a device that can be used to produce an item or achieve a task, but that is not consumed in the process. Informally the word is also used to describe a procedure or process with a specific purpose. Tools that are used in particular fields or activities may have different designations such...

s in the wild. A female gorilla in the Nouabalé-Ndoki National Park
Nouabalé-Ndoki National Park
Nouabal-Ndoki National Park is a national park in the Republic of the Congo. Established in 1993, north of Congo, it is mostly populated with elephants, apes, ranging from Western Lowland Gorillas to chimpanzees and bongo. It is of pristine tropical rainforest with no human habitation within it...

 in the Republic of Congo was recorded using a stick as if to gauge the depth of water whilst crossing a swamp
Swamp
A swamp is a wetland with some flooding of large areas of land by shallow bodies of water. A swamp generally has a large number of hammocks, or dry-land protrusions, covered by aquatic vegetation, or vegetation that tolerates periodical inundation. The two main types of swamp are "true" or swamp...

. 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 40 years previously chimpanzee
Chimpanzee
Chimpanzee, 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 ape
Ape
Apes are Old World anthropoid mammals, more specifically a clade of tailless catarrhine primates, belonging to the biological superfamily Hominoidea. The apes are native to Africa and South-east Asia, although in relatively recent times humans have spread all over the world...

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 Navigator
Hanno the Navigator
Hanno the Navigator was a Carthaginian explorer c. 500 BC, best known for his naval exploration of the African coast...

, 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 who 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
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 physician and missionary Thomas Staughton Savage obtained the first specimens (the skull and other bones) during his time in Liberia
Liberia
Liberia , officially the Republic of Liberia, is a country in West Africa. It is bordered by Sierra Leone on the west, Guinea on the north and Côte d'Ivoire on the east. Liberia's coastline is composed of mostly mangrove forests while the more sparsely populated inland consists of forests that open...

 in Africa
Africa
Africa 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...

. The first scientific description of gorillas dates back to an article by Savage and the naturalist Jeffries Wyman
Jeffries Wyman
Jeffries 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 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 95,000 individuals...

. Other species of gorilla are described in the next couple of years.

Explorer Paul du Chaillu
Paul du Chaillu
Paul 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
Africa
Africa 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...

 from 1856 to 1859. He brought dead specimens to the UK in 1861.

The first systematic study was not conducted until the 1920s, when Carl Akeley
Carl Akeley
Carl Ethan Akeley was a taxidermist, sculptor, biologist, conservationist, inventor, and nature photographer, noted for his contributions to American museums, most notably to the Field Museum of Natural History and the American Museum of Natural History...

 of the American Museum of Natural History
American Museum of Natural History
The American Museum of Natural History , located on the Upper West Side of Manhattan in New York City, United States, 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 Yerkes
Robert Yerkes
Robert Mearns Yerkes was an American psychologist, ethologist, and primatologist best known for his work in intelligence testing and in the field of comparative psychology....

 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 World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, George Schaller
George Schaller
George 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 Leakey
Louis Leakey
Louis Seymour Bazett Leakey was a British 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 Fossey
Dian Fossey
Dian Fossey was an American zoologist who undertook an extensive study of gorilla groups over a period of 18 years. She studied them daily in the mountain forests of Rwanda, initially encouraged to work there by famous anthropologist 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 endangered
Endangered species
An 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...

, and have been subject to intense poaching
Poaching
Poaching is the illegal taking of wild plants or animals contrary to local and international conservation and wildlife management laws. Violations of hunting laws and regulations are normally punishable by law and, collectively, such violations are known as poaching.It may be illegal and in...

 for a long time. Threats to gorilla survival include habitat destruction
Habitat destruction
Habitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms that previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity mainly for the purpose of...

 and the bushmeat
Bushmeat
Bushmeat initially referred to the hunting of wild animals in West and Central Africa and is a calque from the French viande de brousse. Today the term is commonly used for meat of terrestrial wild animals, killed for subsistence or commercial purposes throughout the humid tropics of the Americas,...

 trade. In 2004, a population of several hundred gorillas in the Odzala National Park
Odzala National Park
Odzala 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...

, Republic of Congo was essentially wiped out by the Ebola virus
Ebola virus
Ebola virus causes severe disease in humans and in nonhuman primates in the form of viral hemorrhagic fever. EBOV is a Select Agent, World Health Organization Risk Group 4 Pathogen , National Institutes of Health/National Institute of Allergy and Infectious Diseases Category A Priority Pathogen,...

. A 2006 study published in Science
Science (journal)
Science is the academic journal of the American Association for the Advancement of Science and is one of the world's top scientific journals....

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 extinction
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...

." Conservation efforts include the Great Ape Survival Project
Great Apes Survival Project
The 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 Programme
United Nations Environment Programme
The United Nations Environment Programme coordinates United Nations environmental activities, assisting developing countries in implementing environmentally sound policies and practices. It was founded as a result of the United Nations Conference on the Human Environment in June 1972 and has its...

 and the UNESCO
UNESCO
The United Nations Educational, Scientific and Cultural Organization is a specialized agency of the United Nations...

, and also an international treaty, the Agreement on the Conservation of Gorillas and Their Habitats
Gorilla agreement
The 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 Species
Bonn Convention
The Convention on the Conservation of Migratory Species of Wild Animals aims to conserve terrestrial, marine and avian migratory species throughout their range...

. The Gorilla Agreement
Gorilla agreement
The 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 Kong
King Kong
King Kong is a fictional character, a giant movie monster resembling a gorilla, that has appeared in several movies since 1933. These include the groundbreaking 1933 movie, the film remakes of 1976 and 2005, as well as various sequels of the first two films...

, and pulp fiction such as the stories of Tarzan
Tarzan
Tarzan is a fictional character, an archetypal feral child raised in the African jungles by the Mangani "great apes"; he later experiences civilization only to largely reject it and return to the wild as a heroic adventurer...

 and Conan the Barbarian
Conan the Barbarian
Conan the Barbarian is a fictional sword and sorcery hero that originated in pulp fiction magazines and has since been adapted to books, comics, several films , television programs, video games, roleplaying games and other media...

 have featured gorillas as physical opponents to the titular protagonists.

See also


  • List of apes – notable individual apes
  • List of fictional apes
  • Bili ape
    Bili Ape
    Bili Ape, also Bondo Mystery Ape, is the name given to a large chimpanzee that inhabits Bili Forest in the Democratic Republic of the Congo....


External links