Overview
- The Science paper released Thursday reconstructs a 30-year record at Ngogo in Kibale National Park and documents at least 24 attacks from 2018 to 2024 with seven adult males and 17 juveniles killed, plus 14 disappearances.
- Researchers trace the break to June 24, 2015 when two subgroups clashed and then avoided each other for six weeks, followed by patrols in 2016–2017, a full split by 2018, and a turn to juvenile killings beginning in 2021.
- By 2018 the single community had separated into a smaller western group with 10 adult males and 22 adult females and a larger central group with 30 adult males and 39 adult females, and all observed attacks came from the western side.
- The team highlights likely drivers that weakened cross-group ties, including an exceptional community size of about 200 individuals, the earlier absorption of a neighbor, deaths of well-connected adults in 2014, and a 2017 epidemic that removed a last bridging male.
- Permanent, violent splits in chimpanzees are described as extremely rare, with genetic clues suggesting events like this about once every 500 years, and the case invites cautious insight into how group identity and frayed relationships alone can fuel collective violence.