Lynn Margulis’s foremost scientific contribution is the Serial Endosymbiosis Theory. This theory now has ample evidence to show that all animals, fungi, and plants descend from an ancient series of bacterial mergers to form the eukaryotic or nucleated cell. Moreover, sexual reproduction itself only evolved after the long evolution of the nucleated cell. Margulis’s central contribution to the Gaia hypothesis in collaboration with James Lovelock was her addition of deep time, or “Big History,” in tracing the Gaian system to its emergence in the bacterial biosphere of early life. Writing with her son Dorion Sagan, Margulis presented her ideas to general readers in a series of popular volumes. They write in What is Life?: “Chance mutations, blind and undirected, are touted as the leading source of evolutionary novelty. We […] do not entirely agree. Great gaps in evolution have been leaped by symbiotic incorporation of previously refined components.”

*Text by Bruce Clark in Critical Zone, Fieldbook, 2020, ZKM