Final answer:
An opposable thumb is a thumb that can move across the palm of the hand and touch the tips of the other fingers. It allows primates, including humans, to grasp and hold objects with precision and strength.
Step-by-step explanation:
An opposable thumb is a thumb that can move across the palm of the hand and touch the tips of the other fingers. It allows primates, including humans, to grasp and hold objects with precision and strength. For example, primates like bonobos and capuchin monkeys have opposable thumbs, which give them manual dexterity and the ability to perform complex tasks. Opposable thumbs are a primate trait and are not found in any other group of mammals. They are an important adaptation that allows primates to interact with their environment in unique ways.