with males or dominant over them, even to the extent that females can coerce reluctant males into mating with them. At the top of the hierarchy is a coalition of high-ranking females and males typically headed by an old, experienced matriarch who acts as the decision-maker and leader of the group. Female bonobos typically earn their rank through experience, age, and ability to forge alliances with other females in their group, rather than physical intimidation, and top-ranking females will protect immigrant females from male harassment. While bonobos are often called matriarchal, and while every community is dominated by a female, some males will still obtain a high rank and act as coalitionary partners to the alpha female, often taking initiative in coordinating the groups movements. These males may outrank not only the other males in the group, but also many females. Certain males alert the group to any possible threats, protecting the group from predators such as pythons and leopards. Aggressive encounters between males and females are rare, and males are tolerant of infants and juveniles. A male derives his status from the status of his mother. The mother–son bond often stays strong and continues throughout life. While social hierarchies do exist, and although the son of a high ranking female may outrank a lower female, rank plays a less prominent role than in other primate societies. Relationships between different communities are often positive and affiliative, and bonobos are not a territorial species. Bonobos will also share food with others, even unrelated strangers. Bonobos exhibit paedomorphism (retaining infantile physical characteristics and behaviours), which greatly inhibits aggression and enables unfamiliar bonobos to freely mingle and cooperate with each other. Males engage in lengthy friendships with females and, in turn, female bonobos prefer to associate with and mate with males who are respectful and easygoing around them. Because female bonobos can use alliances to rebuff coercive and domineering males and select males at their own leisure, they show preference for males who are not aggressive towards them. Aging bonobos lose their playful streak and become noticeably more irritable in old age. Both sexes have a similar level of aggressiveness. Bonobos live in a male philopatric society where the females immigrate to new communities while males remain in their natal troop. However, it is not entirely unheard of for males to occasionally transfer into new groups. Additionally, females with powerful mothers may remain