They're considered to be human like hands. They have a thumb like humans which allows them to grip onto trees and maneuver better. It also helps them with their grip onto branches and trees because they rarely come down from up there, so they need to be able to grip tightly even a sleep. I would say it's natural selection due to evolution.
Answer:
Complex organisms evolved from more simple organisms
Explanation:
<em>Fossil records support the fact that complex organisms evolved from more simple organisms.</em>
<u>Fossils are remains of organisms that have been naturally preserved in rock forms. </u>
The study of fossilized remains of organisms has enabled scientists to establish the fact that earlier organisms are simple types and more complex organisms arose from them through a gradual process of change, otherwise known as evolution. Carbon dating of fossils enables scientists to establish the year the organism existed.