Like most animals, the articulates are, above all, individualists: they work for themselves without aid from their brothers, and their existence seems to have no other end than self-protection. Some, however, establish family societies which practice the most perfect communism. .Then there is established among the members of each society a division of labor which renders the individuals collectively responsible. A fertile female or a royal couple are given the reproductive functions, the others are neuters, ordinarily sterile, which provide for the needs of the entire society, and their functions are divided according to their age and their special aptitudes. Thus, each individual depends closely upon the others in order to preserve its life. Communism is substituted for individualism with such strength that it becomes a vital need.

How has this substitution taken place? That is the problem which we are going to try to solve.

This presents two aspects ; the one historical and evolutional, upon which comparative biology sheds light; the other psycho-physiological, belonging to the domain of observation and experiment.