Macaques, such as Japanese monkeys, are common monkeys living widely in Asia. They have diversified greatly into twenty-one living species. I am investigating their diversity, mechanisms, and the history of how their traits have evolved. By means of ecological segregation, they share common habitats, forest type, geographical conditions and life styles of terrestriality vs. arboreality. Macaques have survived climate changes in glacial periods, which likely had a great influence on their phylogeny and morphology. Macaque morphology has been shaped not only by their fundamental life activities, such as feeding or positional behavior, but also by the communication in their societies which varies greatly among species.