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. More recently, a third subspecies has been claimed to exist in one of the species. There is now agreement that there are two species, each with two subspecies. Until recently, gorillas were considered to be a single species, with three subspecies: the western lowland gorilla, the eastern lowland gorilla and the mountain gorilla. Human gene sequences differ only 1.6% on average from the sequences of corresponding gorilla genes, but there is further difference in how many copies each gene has. The closest relatives of gorillas are the other two Homininae genera, chimpanzees and humans, all of them having diverged from a common ancestor about 7 million years ago. The species name was derived from Ancient Greek Γόριλλαι (gorillai) 'tribe of hairy women', as described by Hanno. They called it Troglodytes gorilla, using the then-current name of the chimpanzee genus. The American physician and missionary Thomas Staughton Savage and naturalist Jeffries Wyman first described the western gorilla in 1847 from specimens obtained in Liberia. Skins of gorillai women, brought back by Hanno, are reputed to have been kept at Carthage until Rome destroyed the city 350 years later at the end of the Punic Wars, 146 BC. It is unknown whether what the explorers encountered were what we now call gorillas, another species of ape or monkeys, or humans. Members of the expedition encountered 'savage people, the greater part of whom were women, whose bodies were hairy, and whom our interpreters called Gorillae'.

500 BC), a Carthaginian explorer on an expedition to the west African coast to the area that later became Sierra Leone.

The word 'gorilla' comes from the history of Hanno the Navigator ( c. However, conservation efforts have been successful in some areas where they live. There are many threats to their survival, such as poaching, habitat destruction, and disease, which threaten the survival of the species. Both species are classified as Critically Endangered by the IUCN all subspecies are classified as Critically Endangered with the exception of the mountain gorilla, which is classified as Endangered. There are thought to be around 316,000 western gorillas in the wild, and 5,000 eastern gorillas. 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 Congo near its border with Rwanda. The mountain gorilla inhabits the Albertine Rift montane cloud forests of the Virunga Volcanoes, ranging in altitude from 2,200 to 4,300 metres (7,200 to 14,100 ft).

Although their range covers a small percentage of Sub-Saharan Africa, gorillas cover a wide range of elevations. Gorillas' natural habitats cover tropical or subtropical forest in Sub-Saharan Africa.

1957), who is still alive at the advanced age of 65 years. Gorillas tend to live 35–40 years in the wild. The Eastern gorilla is distinguished from the Western by darker fur colour and some other minor morphological differences. They tend to live in troops, with the leader being called a silverback. Gorillas are the largest living primates, reaching heights between 1.25 and 1.8 metres, weights between 100 and 270 kg, and arm spans up to 2.6 metres, depending on species and sex. The DNA of gorillas is highly similar to that of humans, from 95 to 99% depending on what is included, and they are the next closest living relatives to humans after chimpanzees and bonobos. The genus Gorilla is divided into two species: the eastern gorilla and the western gorilla, and either four or five subspecies. Gorillas are herbivorous, predominantly ground-dwelling great apes that inhabit the tropical forests of equatorial Africa.

Silverback meaning