The instinct that bound our ancestors together is likely the biological product of a process that selects for qualities that improve the chances of the group’s survival. There are two important factors responsible for our advanced social behavior: the traits cooperativeness, empathy and willingness to network are heritable qualities. A reproduction scheme that builds this type of interdependence is necessary for a group to compete successfully, and fits well fits well into those hereditary aspects of human behavior that lead to what has been called “resistance to change” that will be discussed later…
Because of our intense and inherent affinity for those who are similar to our “group” we react instantly to people who appear different from those in our group. For example, threatening faces activate a primitive of the human brain and this reaction has been studied intensively with brain imaging. If a test subject is shown the face of someone with a decidedly different face an area is activated that perceives a threat is approaching. This happened so fast that the subject could not help himself. However, if a viewer is given clues to allow them to think of the person as someone who is potentially helpful, and benign, a more rational part of the brain can suppress the threatening feelings. Sapolsky-Biology
An implication of this fact is that a human’s sense of relatedness can be manipulated. Another example of such manipulation is the sociological concept of pseudokinship and the idea of “bands of brothers.” Military rituals throughout human cultures build such a bond. The unprecedented pseudo kinship of American troops in World War II underscores the strength of this bond. The flip side of pseudokinship is pseudospeciation, where enemies are portrayed as hardly counting as human. Sapolsky-Why Zebras Don’t Get Ulcers