It strikes me that there's a somewhat fuzzy continuum in both directions. The concept of a coherent identity is largely a factor of how aligned the interests of the component entities are. This ranges all the way from individual genes or DNA sequences, through cells and sub-agents in the brain, past the individual human and up through family, community, nation, company, religion, species and beyond.

Coalitions of entities with interests that are more aligned will tend to have a stronger sense of identity. Shifting incentives may lead to more or less alignment of interests and so change the boundaries where common identity is perceived. A given entity may form part of more than one overlapping coalition with a recognizable identity and shifting loyalties between coalitions are also significant.