Animal radical on the left (side-form of
犬, dog) - used broadly for non-canine mammals too. Anchors
猴 in the mammal family alongside
狗 (dog),
猫 (cat),
狼 (wolf),
狐 (fox),
猪 (pig).
犭 became the default 'mammal' radical, which is why monkeys end up here.
