The Gaia hypothesis initially proposed that life, or the biosphere, regulates the climate and atmospheric composition. This idea evolved into Gaia theory, which clarifies that it's not the biosphere alone, but the entire system—life, air, oceans, and rocks—that does the regulating to maintain conditions favourable for life. Microorganisms are recognized as playing a leading and fundamental role in this self-regulating system. The regulation is an automatic, emergent property of the system, not involving foresight, planning, or teleology. Humans are considered a part of Gaia, but not its owners, managers, or stewards.
The Tissue of Gaia from the Symbiotic Earth collection
Lynn Margulis / Hummingbird Films
Lynn Margulis revolutionised biology with her notion of symbiosis, proposing that life evolves through cooperative relationships rather than competition. Her endosymbiotic theory explains how complex cells originated via symbiotic mergers of simpler organisms. Additionally, she co-developed with James Lovelock the Gaia hypothesis, indicating how Earth functions as a self-regulating system where life interacts with the environment to maintain planetary habitability.