Social behavior characterizes the interactions that occur among individuals.
These can be aggressive, mutualistic, cooperative, altruistic, and parental.
When individuals interact repeatedly, social relationships develop and these can form among strangers, relatives,
members of the same or opposite sex, and members of the same or different generations.
Sets of consistent social relationships produce social systems or social organizations that can be variations
on monogamous or polygamous themes of reproduction and involve various types of helpers in cooperative relationships.