Do Monkeys Have Thumbs?

monkeys-thumbs Credit: shankar s./CC-BY 2.0

Old World monkeys from Africa and Asia, as well as some lemurs and lorises, have thumbs. New World monkeys from Central and South America lack opposable thumbs.

In fact, the spider monkey lacks a fifth digit entirely, having only four digits on each hand. It does, however, have five digits on each foot. Monkeys that lack opposable thumbs employ a different kind of grip as an adaptation for living high in trees. They use their whole hand in a strong grip to hold onto branches. The ability of Old World monkeys to touch the tips of their other fingers with their thumb is called a "precision grip."