Gorillas are the largest species of primates. Gorillas are ground-dwelling, predominantly herbivorous apes that inhabit the forests of centralAfrica. Gorillas are divided into two species and (still under debate as of 2008) either four or five subspecies. The DNA of gorillas is highly similar to that of a human, between 95 and 99% depending on what is counted, and they are the next closest living relatives to humans after the two chimpanzee species.
Gorillas' natural habitats cover tropical or subtropical forests in Africa. Although their range covers a small percentage of Africa, gorillas cover a wide range of elevations. The Mountain Gorilla inhabits the Albertine Rift montane cloud forests of the Virunga Volcanoes, ranging in altitude from 2,200–4,300 metres (7,200–14,100 ft). Lowland Gorillas live in dense forests and lowland swamps and marshes as low as sea level, with Western Lowland Gorillas living in Central West African countries and Eastern Lowland Gorillas living in the Democratic Republic of the Congonear its border with Rwanda.
Etymology:
The American physician and missionary Thomas Staughton Savage and naturalist Jeffries Wyman first described the Western Gorilla (they called it Troglodytes gorilla) in 1847 from specimens obtained in Liberia. The name was derived from the Greek word "Γόριλλαι" (Gorillai), a "tribe of hairy women" described by Hanno the Navigator, a Carthaginian navigator and possible visitor (circa 480 BC) to the area that later became Sierra Leone.
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 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. The separate species and subspecies developed from a single type of gorilla during the Ice Age, when their forest habitats shrank and became isolated from each other.
Primatologists 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 (Gorilla gorilla)
§ Western Lowland Gorilla (Gorilla gorilla gorilla)
§ Cross River Gorilla (Gorilla gorilla diehli)
§ Eastern Gorilla (Gorilla beringei)
§ Mountain Gorilla (Gorilla beringei beringei)
§ Eastern Lowland Gorilla (Gorilla beringei graueri)
The proposed third subspecies of Gorilla beringei, which has not yet received a trinomen, 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, although they sometimes walk bipedally for short distances while carrying food or in defensive situations. Adult males also called as silverbacks range in height 1.65–1.75 metres (5 ft 5 in–5 ft 9 in), and in weight 140–200 kg (310–440 lb). Adult females are often half the size of a silverback, averaging about 1.4 metres (4 ft 7 in) tall and 100 kg (220 lb). Occasionally, a silverback of over 1.8 metres (5 ft 11 in) and 230 kg (510 lb) has been recorded in the wild. 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 mandibleprotrudes farther out than the 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 type (B) and, like humans, have individual finger prints. Their eye color is dark brown, framed by a black ring around the iris. 
Intelligence:
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 tools 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 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 chimpanzees had been seen using tools in the wild, famously 'fishing' for termites. Great apes 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.
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