Chimpanzees and bonobos maintain tight inner circles of preferred grooming partners inside their wider social networks, mirroring the layered friendship structures that scientists long assumed were ...

Friendship, it turns out, may run deeper in chimpanzees than a simple preference for grooming partners. A new study from the University of California, Berkeley has found that chimpanzees steal less ...

Female chimpanzees that forge strong, grooming-rich friendships with other females dramatically boost their infants’ odds of making it past the perilous first year—no kin required. Three decades of ...