Part and whole

Accepting multilevel selection has profound implications. It means we can no longer regard the individual as a privileged level of the biological hierarchy. Adaptations can potentially evolve at any level, from genes to ecosystems. Moreover, the balance between levels of selection is not fixed but can itself evolve - and when between-group selection becomes sufficiently strong compared with within-group selection in a given population, a major transition occurs and the group becomes a higher-level organism in its own right.

-- from Survival of the selfless by David Sloan Wilson and Edward O. Wilson. [Image: flock of starlings, U.K.]