Dormancy in the Origin, Evolution and Persistence of Life on Earth
Life has existed on Earth for most of the planet’s history, yet major gaps and unresolved questions remain about how it first arose and persisted. Early Earth posed numerous challenges for life, including harsh and fluctuating environments.
Today, many organisms cope with such conditions by entering a reversible state of reduced metabolic activity, a phenomenon known as dormancy. This process protects inactive individuals and minimizes the risk of extinction by preserving information that stabilizes life-system dynamics.
Here, we develop a framework for understanding dormancy on early Earth, beginning with a primer on dormancy theory and its core criteria. We hypothesize that dormancy-like mechanisms acting on chemical precursors in a prebiotic world may have facilitated the origin of life. Drawing on evidence from phylogenetic reconstructions and the fossil record, we demonstrate that dormancy is prevalent across the tree of life and throughout deep time.
These observations lead us to consider how dormancy might have shaped nascent living systems by buffering stochastic processes in small populations, protecting against large-scale planetary disturbances, aiding dispersal in patchy landscapes and facilitating adaptive radiations. Given that dormancy is a fundamental and easily evolved property on Earth, it is also likely to be a feature of life elsewhere in the universe.
Examples of ancient dormancy. Dormancy is prevalent among extant lineages, but is also common in Earth’s fossil record. (A) Sporocarps of slime moulds preserved in amber 100 million years ago (Ma) [28]. (B) Resting eggs from aquatic crustaceans (Daphnia) have been recovered from 130 Ma sediments [29]. (C) Some bacteria related to Bacillus form long-lived endospores that have been resuscitated from permafrost dated to >1 Ma [30]. (D) Cryptospores related to primitive plants have been dated to 450 Ma [31]. Panel (B) image is courtesy of J. Haney and panel (C) image is courtesy of D. Schwartz. — Proc Biol Sci. via PubMed
Dormancy in the origin, evolution and persistence of life on Earth, Proc Biol Sci. via PubMed (open access)
Astrobiology
