An overview : identity from bacteria to belief -- The prokaryotes : viruses, hyperparasites and the origin of group identity -- Sensory systems (light, odor, pheromones) in communities of oceanic microbes -- Subjugation of the individual : prokaryotic group living : blooms, slime and mats -- Animal group identity : from slime to worms, emergence of the brain -- Group identity in aquatic animals : learning to belong -- Development of tetrapod group identity, the smell of self -- Origin of primate group identity : vision and the great ERV invasion -- Human group identity : language and a social mind