The number of adult makes seems to determine the size of the range they can control. By 1990, make numbers and range size had both increased again. Adult females do not permanently pair with males. She will mate promiscuously with many different males. In this situation, the male has exclusive mating rights to that female, which obviously increases his chance of producing offspring.
Family ties are very close.
Infants are born after 8 months pregnancy, well-formed and able to cling tightly to the mother's belly. Normally births are single, but 2 instances of twins has been observed at Gombe. The infant nurses for 3 years and is then gradually weaned during the fourth and fifth years. However, it a female accompanied by tow or even three dependent offspring, spaced 4-5 years apart. Even after reaching adulthood at 11-12 years, a son or doughter will continue to spend a lot for time with its mother for the rest of her life.