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  Panspermia (Greek, ‘seeds of all’) is the idea that life on Earth was seeded from from elsewhere in the universe. The term was coined by the Swedish chemist Svante Arrhenius in his book Worlds in the Making (1908). He proposed that life had arrived on the Earth in the form of spores or microorganisms, which had been carried through space by solar winds and radiation from a distant planet. The theory was initially popular, presumably because it provided a distraction from the controversial ideas of evolution and biopoiesis, and it has been cultivated by sf authors who have proposed that the seed may have been delivered intentionally. It is possible that panspermia could have occurred, and the lack of a fossil record pertaining to the earliest period of life on Earth means that the the theory can be neither proven nor refuted. However, it is difficult to imagine how a living organism, even in the form of a spore, could survive the rigours of radiation and vacuum for the time required to travel to Earth. Furthermore, it seems unlikely that such a seed would have arrived to find suitable conditions for its growth on a world which had previously borne no life. Finally, the concept of panspermia does not provide an alternative for either biopoiesis or evolution because the life which the seed represents must have appeared from non-living matter at some stage and, after arriving on Earth, must have evolved to produce the biodiversity which is extant today. RB

See also biogenesis.Further reading Francis Crick, Life Itself; , Fred Hoyle, Lifecloud.



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