Final answer:
Orangutans are the type of ape that has a solitary social system. They are arboreal and exhibit sexual dimorphism, with males being much larger. Despite occasional social behaviors, they predominantly live alone, unlike other African great apes like gorillas and chimpanzees.
Step-by-step explanation:
The type of ape that typically has a solitary social system is the orangutan. While other apes such as gorillas and chimpanzees live in family groups, orangutans generally prefer a solitary lifestyle. This behavior has been observed across the two species native to Indonesia, the Bornean orangutan (P. pygmaeus) and the Sumatran orangutan (P. abelii), as well as the newly identified species from Sumatra, the Tapanuli orangutan (Pongo tapanuliensis).
Orangutans are highly arboreal, spending much of their time in trees, and they exhibit significant sexual dimorphism, with males being much larger than females and possessing distinctive cheek and throat pouches upon maturity. Despite earlier assumptions that orangutans are reclusive, studies, such as those by Dutch primatologist Carel van Schaik, show that they can be more social than initially thought, particularly in instances of tool use and passing down skills to offspring. Nevertheless, compared to other great apes that live in central Africa, such as gorillas, chimpanzees, and bonobos, orangutans have a distinct social structure that emphasizes their solitary nature.