This is a very wide-ranging topic but the elements listed are those particularly important for any sociobiological approach to the functioning of societies. Religion has been in the past, and still is in a number of countries, the main cohesive force holding populations, particularly genetically disparate ones, together in one system. Patterns of sexual behaviour (often strongly influenced by religious beliefs and prescriptions) in different societies have determined the organisational character of the society - from the nuclear family (now apparently in decline) in most Western countries and the extended family of earlier periods which still survives over a large part of the third world. Both religion and patterns of sexual behaviour as cohesive forces have been, and increasingly will be, radically challenged by science, both as a mode of thought and as the source of technologies which change the environment in which societies operate, both at the societal level and at the level of the individual human being. A sociobiology of societies has to be founded on a sociobiology of the individuals forming the society, where the validity of the insights of evolutionary psychology is for consideration, and on a biologizing of sociology, the interpretation of social forms in the light of evolutionary thinking. The survival of populations (interpreted as gene pools) and of societal forms are interlocked; a sociobiology of societies, biological sociology, can start to consider the conditions and forces which over long periods determine the relative success or failure of nations and social systems.