Scientists establish the age of a rock or fossil based on natural radioactive decay and certain elements such as potassium and carbon, this is used to make reliable “clocks” to date ancient events.
(Sorry if not all is accurate hope it helps)
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.
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An intrauterine device, also known as intrauterine contraceptive device or coil, is a small, often T-shaped birth control device that is inserted into the uterus to prevent pregnancy. IUDs are one form of long-acting reversible birth control.