Chimp friendships curb stealing

A controlled experiment at Ngamba Island found that chimpanzees were less likely to steal food from closely bonded groupmates than from more distant individuals, and that victims reacted more angrily to friends but forgave them faster. This suggests selective restraint and reciprocal expectations exist in chimp friendships. — If friendship‑based restraint and forgiveness predate humans, debates about whether cooperation is cultural or evolved should account for biological building blocks of moral behavior.