A simple, small, autonomous family‐based group, the definition of which may be no more than the fact that its members feel closely enough related not to intermarry. There are no specialized or formalized institutions or groups which can be recognized as economic, political, or religious, for the band itself is the organization that undertakes all roles. Leadership and the division of labour is usually by age or sex differentiations. This simple form of human social organization flourished for most of prehistory. Bands consist of a family or a series of families, usually ranging from 20 to 50 people.