Gorillas have evolved a number of adaptations that allow them to survive in the rainforests of Central Africa. Their social nature, herbivorous habits and secretive nature are among their most important adaptations, but they do have others, such as their expressive faces.
Gorillas form groups of up to 12 and the largest males, called silverbacks, lead and protect the group. Gorillas derive protection from their social nature, but it also helps them to find more food. In order for such societies to function well, gorillas have had to evolve a number of different ways to communicate. In addition to body language and vocalizations, gorillas, like the other great apes, have very expressive faces that allow them to convey emotions, desires and needs to other apes in their group.
By existing almost solely on vegetation, gorillas do not have to expend energy chasing or fighting with prey. Nor do they have to relocate if their prey leaves; the trees and plants that provide their food are a stationary resource. However, herbivorous foods provide fewer calories per unit of time spent acquiring the food than animal-based foods do.
Gorillas are very secretive animals, despite their large and formidable size. If they smell, see or hear a threat, they often move off quietly to avoid detection.