Diverse natural systems in the universe from stars to organisms have finite “life cycles” (durations of existence). In my review, I attempt to answer fundamental but little explored questions about birth-death cycles, including “why do they exist?”, “what do they have in common?”, and “how/why do they vary?” Various physical and biological systems have life cycles because they cannot avoid “death”, metaphorically speaking. Thus, if their type is to persist, they must replace themselves. All systems with life cycles are dissipative structures with a generative phase of growth and increasing order driven by energy uptake/use and a degenerative phase of degrowth and decreasing order driven by entropy production and accidental damage. Life cycles vary in rapidity and duration, often in relation to system size. The life cycles of living systems also differ from those of non-living systems in using information to regulate their birth and death, at least in part. Living systems are born via self-production, whereas non-living systems are “born” de novo. Thus, living systems perpetuate themselves by means of branching ancestor–descendant lineages, thereby enabling the cumulative evolution of their relatively high levels of diversity and complexity. Living systems (from cells to societies) are also extraordinary in having multi-layered compound cycles, i.e., “cycles within cycles”. Based on my comparative analysis of living and non-living systems across the universe, I propose a preliminary, multi-mechanistic theory of life cycles and their origins.
Douglas S. Glazier (Thu,) studied this question.