Evolution of multicellularity

A yeast cell divides, but its daughters stay attached. A branching cluster grows, then pieces break off and grow into new clusters. Researchers evolved this life cycle in the lab by repeatedly keeping fast-settling yeast. How does a cell group go further and become a lasting organism, with different cells doing different jobs?[1] [2] [3]

In a body, a cell may multiply while the organism fails to survive or reproduce. How did cell groups evolve coordinated development and specialized work despite that possible conflict? Laboratory snowflake yeast supplies an early step: attached daughters form clusters that grow and release smaller offspring clusters. Favoring fast-settling clusters changed their reproductive life cycle, evidence of group selection. Starting a body from one cell, a single-cell bottleneck, can align descendants' interests, but mutations can introduce differences. Nor is that starting point universal: animals that bud or split can pass many cells into the next individual. Explaining stable complex bodies must accommodate these different life cycles, rather than assume one safeguard removes all conflict.[1] [3]

Several transitions and cooperation mechanisms are understood. The conditions producing stable, complex organisms are still incomplete.[1] [2]

Experiments and comparisons explain particular routes. A general account must also accommodate lineages lacking familiar conflict-limiting features, rather than presume conflict disappears.[1] [2]

It explains how life built bodies from cells that once reproduced on their own.[1] [2]

This would connect how bodies develop with why their cellular cooperation survives competing reproductive interests.[1]