young males have been observed to leave their natal groups anywhere from two to four years of age. however, one study showed that most juveniles left before they were three, which is before most males reach sexual maturity. this contrasts with an earlier study in which juveniles were observed to leave later, at sexual maturity, indicating that there may be variation between groups. the reason young males leave their natal group is also contested. dominant males have been observed to act aggressively toward younger males in captivity. however, observations of wild patas monkeys has shown young males leaving the group in which they were born without any aggressive behavior from the adult male. the juveniles, in the time shortly before they leave, spend increasingly less and less time with the adult females in the group. however, juvenile males do not change the amount of time they spend near the adult male. this may indicate weakening of matrilineal ties, rather than male aggression, as the main reason juveniles disperse from their natal group.