Why do people like to form groups?

People like to form groups for the sole purpose of survival. it is an inherited trait and evidences can be seen when an infant cries and seeks the parent's attention by crying. this means, the baby needs to with somebody, a parent. and when he grows up, he gets acquainted with people around him and later his neighbors and classmates. This tendency is called socialization. and its either one joins a group because they need to or they want to in order to have preservation in one's status and role