The last common ancestor with humans and old-world monkeys lived around 29 million years ago.

Around 25 to 29 million years ago, Old World monkeys, including species like baboons and macaques, branched off from the common ancestor shared with apes. Unlike their ape cousins, Old World monkeys retained their tails and adapted to a wider range of habitats, from forests to savannas. Baboons, known for their ground-dwelling behavior, exhibit strong social structures and advanced communication. However, they lack the opposable thumbs and tool use that evolved in the ape lineage. This branching marked a key evolutionary moment, setting the stage for the development of the tailless apes, including gibbons and later great apes.