Each band is composed of clans. Unlike other baboons, males remain in the same clan for life. Males have a harem of females, which they defend from other males. The females are ruled by aggression and remain by the male's side at all times. Young males acquire harems by befriending sexually immature females, who the other males are not yet interested in, and so are met with little resistance.
Hamadryas baboons are diurnal and spend most of their time on the ground.
After a gestation period of 165-174 days, females give birth to one infant. The ancient Egyptians considered hamadryas baboons to be the sacred attendants of Thoth, the scribe to the gods.