Chimpanzees live in large communities that can range in size from 15 to 120 members. While a community may be big, the social structure constantly changes with individuals breaking off into smaller sub groups, many times with 6 or fewer chimps. Although, every once in a while there will be a gathering of the larger community and chimps will get together to play, breed and groom.
According to The Jane Goodall Institute, relationships between chimpanzees can last a lifetime. The site notes that mother-daughter relationships can be particularly strong as mothers stay with their young until around the age of seven. Siblings and pairs of male friends can also be seen together, and communication between smaller groups is common with chimps calling out longer distances through the pant hoot, a type of verbal communication.
Grooming is one of the most important behaviors to keep chimp communities close. By grooming the primates develop their friendships, and calm and reassure others in their group.
And, like elephants and people, chimpanzees also mourn the loss of their loved ones.