Gorillas, the largest of the living primates, are ground-dwelling herbivores that inhabit the forests of Africa. Gorillas are divided into two species and (still under debate as of 2008) either four or five subspecies. The DNA of gorillas is 98%–99% identical to that of a human, and they are the next closest living relatives to humans after the two chimpanzee 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 Gorilla inhabits the Albertine Rift montane cloud forests of the Virunga Volcanoes, 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 level.

Etymology

The American physician and missionary Thomas Staughton Savage first described the Western Gorilla (he called it Troglodytes gorilla) in 1847 from specimens obtained in Liberia. The name was derived from the Greek word 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.

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 copies each gene has.

Primatologists continue to explore the relationships between various gorilla populations. The species and subspecies listed here are the ones upon which most scientists agree.Fact: date=July 2008

• 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.

Physical characteristics

Gorillas move around by knuckle-walking. 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 mandible protrudes farther out than the maxilla.