In speculating about the causes of social interaction, there are three readily identifiable causes of social interaction: requirement, desire, and need.
Requirement: All humans live within the confines of a sovereign nation, even if they live in isolated and unregulated areas. At some point these days, government agents, scientists, tourists, or people who are just lost, will impose some form of social interaction on others, no matter how isolated. At minimum, there will be social interaction with family, the tribe, and other tribes of humans who live in the same areas. Required social interaction can be seen as interaction that is imposed on the individual.
Humans in developed countries must interact with government authorities, neighbors, co-workers, clients, customers, and a host of others. It does not matter whether we are isolated and stay mostly alone, or whether we spend all of our waking hours in the presence of others, some form of interaction will be imposed on us.
Desire: Whether it is desire for romantic love, parental love, love of family and friends or love of attention. Desire for love is a strong driving force which compels humans to interact with others on a personal basis. Desire for safety, companionship, community, and support compels most of us to live in areas where access to organized sources of social interaction are readily available. Desire for something better, something bigger, or something different motivates us to travel away from our homes of origin.
Need: Many humans are driven by an infinite list and range of needs. Whether there is need to trade craft, skill or labor for those essentials that cannot be independently obtained, or whether there is need to prey on other humans and to do them harm, need is the overriding and most powerful force that drives humans into social interaction with each other.
In speculating about how desire, need, and requirement are identifiable as causes of social interaction, the levels of isolation and independence in living can help to identify the differences in how social interactions happen within the contexts of desire, need, and requirement.
In parts of the world where humans live in the maximum conditions of independence, isolation and self regulation, family and tribal alliances are strong. Need outweighs desire and requirement in most dealings. Requirement is imposed based on time tested survival, governance, and spiritual knowledge that may not have changed in centuries. Desire develops within an extremely limited and homogeneous culture, where there is much agreement about beliefs, rules, and regulations, and thus what is desirable. Racial and ethnic homogeneity within and between the tribes, tribal alliances, and agreement about the major issues in life are at the maximum in the extremely isolated and independent.
Where humans live in medium conditions of independence, isolation, and self regulation, alliances are based on mutual need and support, but with greater differences in all aspects of life. We may tend to think that the vast grain growing regions of the Midwest contain homogeneous people of one race, descended from one European culture, and in agreement on everything, but that is far from the case. Access to better technology allows for work and social interactions in far away places. Advances in delivery of government oversight, intervention and services allows for better prevention and response to disasters or medical crises. Advances in communication allow for social interaction in a vast array of new arenas. As a result, traditional racial, spiritual, economic, behavioral,cultural and ethnic homogeneity is fractured.
Desires expand beyond the simple things in life. Needs are expanded as the processes involved in making adequate farming income becomes more complicated. Requirement becomes more complex and difficult to meet. Fractures in family, community, and homogeneity become profound divisions over time.
Where humans live in maximum conditions of dependency for the necessities of life, highly populated and well developed urban and suburban areas are the setting. There is maximum diversity in all aspects of life. Even when there are pockets of ethnic homogeneity, far more interaction and cooperation with people from all parts of the world is still needed in order to satisfy need, desire, and requirement. New forms of alignment and alliance are created. These alliances ebb and flow on lines of religion, political leanings, educational level, work place, distance from immediate and extended family, economic standing, and ethnicity. Social interaction may then be seen as a far more fluid and volatile entity in the urban and suburban environment. The components of desire, requirement and need become far more varied, rapidly changing, and complex.