Editing Spontaneous generation (section)

=== Pre-Socratic philosophers ===

Active in the 6th and 5th centuries BCE, early Greek philosophers, called ''physiologoi'' in antiquity (Greek: φυσιολόγοι; in English, physical or [[Natural philosophy|natural philosophers]]), attempted to give natural explanations of [[phenomena]] that had previously been ascribed to the agency of the gods.<ref>{{cite book | last=Guthrie |first=William Keith Chambers |author-link=W. K. C. Guthrie |title=The Presocratic Tradition from Parmenides to Democritus |date=June 1965 |page=13 |publisher=Cambridge University Press |isbn=0-317-66577-4 |url=https://archive.org/details/historyofgreekph0002unse}}</ref> The ''physiologoi'' sought the material principle or ''[[arche]]'' (Greek: ἀρχή) of things, emphasizing the rational unity of the external world and rejecting theological or mythological explanations.<ref name="seyffert480">{{cite book |last=Seyffert |first=Oskar |year=2017 |origyear=1894 |title=Dictionary of Classical Antiquities |publisher=Norderstedt Hansebooks |page=480 |isbn=978-3337196868 |url=https://archive.org/details/dictionaryofclas00seyfrich/page/n3/mode/2up }}</ref>

[[Anaximander]], who believed that all things arose from the elemental nature of the universe, the ''[[Apeiron (cosmology)|apeiron]]'' (ἄπειρον) or the "unbounded" or "infinite", was likely the first western thinker to propose that life developed spontaneously from nonliving matter. The [[substance theory|primal chaos]] of the ''apeiron,'' eternally in motion, served as a platform on which elemental opposites (e.g., ''wet and dry'', ''hot and cold'') generated and shaped the many and varied things in the world.<ref>{{cite book |title=The Legacy of Parmenides: Eleatic Monism and Later Presocratic Thought |author=Curd, Patricia |year=1998 |publisher=[[Princeton University Press]] |page=77 |isbn=0-691-01182-6 |url=https://books.google.com/books?id=x2JX1ulXzogC&pg=PA77}}</ref> According to [[Hippolytus of Rome]] in the third century CE, Anaximander claimed that fish or fish-like creatures were first formed in the "wet" when acted on by the heat of the sun and that these aquatic creatures gave rise to human beings.<ref>{{cite book |last1=Kahn |first1=Charles H. |author-link = Charles H. Kahn |title=Anaximander and the Origins of Greek Cosmology |date=1994 |publisher=Hackett Publishing |isbn=0872202550 |pages=247 |url=https://archive.org/details/anaximanderorigi00kahn/page/n9/mode/2up}}</ref> The Roman author [[Censorinus]], writing in the 3rd century, reported:

{{quote|text=Anaximander of Miletus considered that from warmed up water and earth emerged either fish or entirely fishlike animals. Inside these animals, men took form and embryos were held prisoners until puberty; only then, after these animals burst open, could men and women come out, now able to feed themselves.<ref>[[Censorinus]], ''[https://archive.org/details/b30335978/page/n11/mode/2up?view=theater De Die Natali]'', IV, 7</ref>}}

The Greek philosopher [[Anaximenes of Miletus|Anaximenes]], a pupil of Anaximander, thought that air was the element that imparted life and endowed creatures with motion and thought. He proposed that plants and animals, including human beings, arose from a primordial terrestrial slime, a mixture of earth and water, combined with the sun's heat. The philosopher [[Anaxagoras]], too, believed that life emerged from a terrestrial slime. However, Anaximenes held that the seeds of plants existed in the air from the beginning, and those of animals in the [[Aether (classical element)|aether]]. Another philosopher, [[Xenophanes]], traced the origin of man back to the transitional period between the fluid stage of the Earth and the formation of land, under the influence of the Sun.<ref>{{cite book |last=Osborn |first=Henry Fairfield |author-link=Henry Fairfield Osborn |title=From the Greeks to Darwin: An outline of the development of the evolution idea|url=https://archive.org/details/fromgreekstodar01osbogoog |date=1894 |publisher=Macmillan |location=New York}}</ref>

In what has occasionally been seen as a prefiguration of a concept of [[natural selection]], [[Empedocles]] accepted the spontaneous generation of life, but held that different forms, made up of differing combinations of parts, spontaneously arose as though by trial and error: successful combinations formed the individuals present in the observer's lifetime, whereas unsuccessful forms failed to reproduce.<ref>{{cite journal |last=Zirkle |first=Conway |author-link=Conway Zirkle |title=Natural Selection before the "Origin of Species" |journal=Proceedings of the American Philosophical Society |date=1941 |volume=84 |issue=1 |pages=71–123 |jstor=984852 |url=https://www.jstor.org/stable/984852 |access-date=4 January 2023 |archive-date=31 March 2023 |archive-url=https://web.archive.org/web/20230331015709/https://www.jstor.org/stable/984852 |url-status=live }}</ref>