Eastern gorilla
Grauer's gorillas and mountain gorillas were previously thought to be two of the three subspecies of one single species, the gorilla ("Gorilla gorilla"). However, genetic research has shown that the two eastern subspecies are far more closely related than the western subspecies: the western lowland gorilla ("G. gorilla gorilla"), which justified the separate classification. The two eastern subspecies are now classified as "G. beringei".
Bornean orangutan
The Bornean orangutan is the third-heaviest living primate after the two species of gorilla, and the largest truly arboreal (or tree-dwelling) animal alive today. Body weights broadly overlap with the considerably taller "Homo sapiens", but the latter is considerably more variable in size. By comparison, the Sumatran orangutan is similar in size but, on average, is marginally lighter in weight. A survey of wild orangutans found that males weigh on average , ranging from , and long; females average , ranging from , and long. While in captivity, orangutans can grow considerably overweight, up to more than . The heaviest known male orangutan in captivity was an obese male named "Andy", who weighed in 1959 when he was 13 years old.