As multicellularity evolves and the organisms become more complex, the individual elements whether cells, individual insects in colonies, or individual computers in complex networks, tend to specialize and become simpler.
To those steeped in Object Oriented design, this should be familiar; you've seen something similar in many a refactoring process.
Specialization is possible because the larger organism provides a simpler, more stable, environment within which the elements collaborate.
Specialization is necessary because behavior that is too general places an expensive maintenance burden on the elements and exposes too much "surface area" to predatory attack.
From Cyberyota's four principles.