Table of Contents
Symbiogenesis deals with the idea that new biological structures, species, or higher-level groups can arise through long-term, intimate cooperation between different organisms. Instead of evolution occurring only through gradual change within a single lineage, symbiogenesis emphasizes that merging and integration of formerly independent organisms can be a powerful evolutionary force.
In this chapter, the focus is on how “living together” can fundamentally shape the origin and evolution of life, especially by forming new, more complex units from simpler partners. The later subsections will consider:
- how widespread and varied coexistence among organisms is (“Life Means Living Together”),
- how different kinds of interactions (competition, symbiosis, commensalism, antibiosis) can have evolutionary consequences,
- and how one particularly far‑reaching form of symbiogenesis — the endosymbiotic origin of eukaryotic cells from prokaryotic ancestors — likely created an entirely new level of cellular complexity.
Symbiogenesis thus connects ecology (interactions among organisms) with evolutionary biology (origin of new forms) and helps explain why cooperation, alongside competition, is central to the history of life.