Suspended animation

Suspended animation is the temporary (short- or long-term) slowing or stopping of biological function so that physiological capabilities are preserved. It may be either hypometabolic or ametabolic in nature. It may be induced by either endogenous, natural or artificial biological, chemical or physical means. In its natural form, it may be spontaneously reversible as in the case of species demonstrating hypometabolic states of hibernation. When applied with therapeutic intent, as in deep hypothermic circulatory arrest (DHCA), usually technologically mediated revival is required. Suspended animation is understood as the pausing of life processes by exogenous or endogenous means without terminating life itself. Breathing, heartbeat and other involuntary functions may still occur, but they can only be detected by artificial means. For this reason, this procedure has been associated with a lethargic state in nature when animals or plants appear, over a period, to be dead but then can wake up or prevail without suffering any harm. This has been termed in different contexts hibernation, dormancy or anabiosis (the latter in some aquatic invertebrates and plants in scarcity conditions). In July 2020, marine biologists reported that aerobic microorganisms (mainly), in "quasi-suspended animation", were found in organically-poor sediments, up to 101.5 million years old, below the seafloor in the South Pacific Gyre (SPG) ("the deadest spot in the ocean"), and could be the longest-living life forms ever found. This condition of apparent death or interruption of vital signs may be similar to a medical interpretation of suspended animation. It is only possible to recover signs of life if the brain and other vital organs suffer no cell deterioration, necrosis or molecular death principally caused by oxygen deprivation or excess temperature (especially high temperature). Some examples of people that have returned from this apparent interruption of life lasting over half an hour, two hours, eight hours or more while adhering to these specific conditions for oxygen and temperature have been reported and analysed in depth, but these cases are not considered scientifically valid.