Editing Spontaneous generation (section)

== Antiquity ==

=== 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 |orig-date=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>

=== Aristotle ===
{{further|Aristotle's biology}}

In [[Aristotle's biology|his biological works]], the natural philosopher [[Aristotle]] theorized extensively the reproduction of various animals, whether by [[sexual reproduction|sexual]], [[parthenogenesis|parthenogenetic]], or spontaneous generation. In accordance with his fundamental theory of [[hylomorphism]], which held that every physical entity was a compound of matter and form, Aristotle's basic theory of sexual reproduction contended that the [[semen|male's seed]] imposed form, the set of characteristics passed down to offspring on the "matter" ([[menstrual blood]]) supplied by the female. Thus female matter is the ''[[Four causes#Matter|material cause]]'' of generation—it supplies the matter that will constitute the offspring—while the male semen is the ''[[Four causes#Agent|efficient cause]]'', the factor that instigates and delineates the thing's existence.<ref name=Leroi2014>{{cite book |last=Leroi |first=Armand Marie |author-link=Armand Marie Leroi |title=The Lagoon: How Aristotle Invented Science |title-link=Aristotle's Lagoon |publisher=Bloomsbury |date=2014 |isbn=978-1-4088-3622-4 |pages=215–221}}</ref><ref>{{cite book |editor-last=Brack |editor-first=André |title=The Molecular Origins of Life |year=1998 |publisher=Cambridge University Press |isbn=978-0-521-56475-5 |page=[https://archive.org/details/molecularorigins0000brac/page/1 1] |chapter=Introduction |chapter-url=http://assets.cambridge.org/97805215/64755/excerpt/9780521564755_excerpt.pdf |url=https://archive.org/details/molecularorigins0000brac/page/1 }}</ref> Yet, Aristotle proposed in the ''[[History of Animals]]'', many creatures form not through sexual processes but by spontaneous generation:

{{quote|Now there is one property that animals are found to have in common with plants. For some plants are generated from the seed of plants, whilst other plants are self-generated through the formation of some elemental principle similar to a seed; and of these latter plants some derive their nutriment from the ground, whilst others grow inside other plants ... So with animals, some spring from parent animals according to their kind, whilst others grow spontaneously and not from kindred stock; and of these instances of spontaneous generation some come from putrefying earth or vegetable matter, as is the case with a number of insects, while others are spontaneously generated in the inside of animals out of the secretions of their several organs.<ref name="HistAnimV">{{cite book |author=Aristotle |author-link=Aristotle |others=translated by D'Arcy Wentworth Thompson |title=History of Animals |url=https://ebooks.adelaide.edu.au/a/aristotle/history/complete.html |orig-year=c. 343 BCE |year=1910 |publisher=Clarendon Press |location=Oxford |chapter=Book V |chapter-url=http://ebooks.adelaide.edu.au/a/aristotle/history/book5.html |isbn=978-90-6186-973-3 |access-date=7 January 2009 |archive-date=8 May 2018 |archive-url=https://web.archive.org/web/20180508025913/https://ebooks.adelaide.edu.au/a/aristotle/history/ |url-status=dead }}</ref>|Aristotle|''[[History of Animals]]'', Book V, Part 1}}

According to this theory, living things may come forth from nonliving things in a manner roughly analogous to the "enformation of the female matter by the agency of the male seed" seen in sexual reproduction.<ref name=Lehoux2017p22>{{cite book |last1=Lehoux |first1=Daryn |title=Creatures Born of Mud and Slime: The Wonder and Complexity of Spontaneous Generation |date=2017 |publisher=Johns Hopkins University Press |location=Baltimore |page=22 |isbn=9781421423814 |url=https://books.google.com/books?id=E749DwAAQBAJ}}</ref> Nonliving materials, like the seminal fluid present in sexual generation, contain ''[[pneuma]]'' (πνεῦμα, "breath"), or "[[vital heat]]". According to Aristotle, ''pneuma'' had more "heat" than regular air did, and this heat endowed the substance with certain vital properties:

{{quote|The power of every soul seems to have shared in a different and more divine body than the so called [four] elements ... For every [animal], what makes the seed generative inheres in the seed and is called its "heat". But this is not fire or some such power, but instead the ''pneuma'' that is enclosed in the seed and in foamy matter, this being analogous to the element of the stars. This is why fire does not generate any animal{{nbsp}}... but the heat of the sun and the heat of animals does, not only the heat that fills the seed, but also any other residue of [the animal's] nature that may exist similarly possesses this vital principle.|Aristotle|''[[Generation of Animals]]'', 736b29ff.<ref>{{cite book |last1=Lehoux |first1=Daryn |title=Creatures Born of Mud and Slime: The Wonder and Complexity of Spontaneous Generation |date=2017 |publisher=Johns Hopkins University Press |location=Baltimore |page=23}}</ref>}}

Aristotle drew an analogy between the "foamy matter" (τὸ ἀφρῶδες, ''to aphrodes'') found in nature and the "seed" of an animal, which he viewed as being a kind of foam itself (composed, as it was, from a mixture of water and ''pneuma''). For Aristotle, the generative materials of male and female animals (semen and menstrual fluid) were essentially refinements, made by male and female bodies according to their respective proportions of heat, of ingested food, which was, in turn, a byproduct of the elements earth and water. Thus any creature, whether generated sexually from parents or spontaneously through the interaction of vital heat and elemental matter, was dependent on the proportions of ''pneuma'' and the various elements which Aristotle believed comprised all things.<ref>{{cite book |last1=Lehoux |first1=Daryn |title=Creatures Born of Mud and Slime |date=2017 |publisher=Johns Hopkins University Press |pages=26–28}}</ref> While Aristotle recognized that many living things emerged from [[Putrefaction|putrefying]] matter, he pointed out that the putrefaction was not the source of life, but the byproduct of the action of the "sweet" element of water.<ref>{{cite book |author=Aristotle |author-link=Aristotle |others=translated by Arthur Platt |title=On the Generation of Animals |url=https://ebooks.adelaide.edu.au/a/aristotle/generation/complete.html |access-date=2009-01-09 |orig-year=c. 350 BCE |year=1912 |publisher=Clarendon Press |location=Oxford |chapter=Book III |chapter-url=http://ebooks.adelaide.edu.au/a/aristotle/generation/book3.html |isbn=90-04-09603-5 |archive-date=2015-09-10 |archive-url=https://web.archive.org/web/20150910034528/https://ebooks.adelaide.edu.au/a/aristotle/generation/complete.html |url-status=dead }}</ref>

{{quote|Animals and plants come into being in earth and in liquid because there is water in earth, and air in water, and in all air is vital heat so that in a sense all things are full of soul. Therefore living things form quickly whenever this air and vital heat are enclosed in anything. When they are so enclosed, the corporeal liquids being heated, there arises as it were a frothy bubble.|Aristotle|''[[Generation of Animals]]'', Book III, Part 11}}

With varying degrees of observational confidence, Aristotle theorized the spontaneous generation of a range of creatures from different sorts of inanimate matter. The [[testacea]]ns (a genus which for Aristotle included [[bivalvia|bivalves]] and snails), for instance, were characterized by spontaneous generation from mud, but differed based upon the precise material they grew in—for example, [[clam]]s and [[scallop]]s in sand, [[oyster]]s in slime, and the [[barnacle]] and the [[limpet]] in the hollows of rocks.<ref name=HistAnimV/>

=== Latin and early Christian sources ===

Athenaeus dissented towards spontaneous generation, claiming that a variety of [[anchovy]] did not generate from [[roe]], as Aristotle stated, but rather, from [[sea foam]].<ref>{{cite book |author=Athenaeus of Naucratis |author-link=Athenaeus |editor-last=Yonge |editor-first=C. D. |title=The deipnosophists, or, Banquet of the learned of Athenæus |url=http://digicoll.library.wisc.edu/cgi-bin/Literature/Literature-idx?type=article&did=Literature.AthV1.i0010&id=Literature.AthV1&isize=M&pview=hide |series=University of Wisconsin Digital Collection |volume= I |publisher=Henry G. Bohn |location=London |pages=433–521 |chapter=Book VII |archive-url=https://web.archive.org/web/20121021022851/http://digicoll.library.wisc.edu/cgi-bin/Literature/Literature-idx?type=article&did=Literature.AthV1.i0010&id=Literature.AthV1&isize=M&pview=hide |archive-date=21 October 2012 |chapter-url=http://digicoll.library.wisc.edu/cgi-bin/Literature/Literature-idx?type=article&did=LITERATURE.ATHV1.I0010&isize=M&pview=hide }}</ref>

As the dominant view of philosophers and thinkers continued to be in favour of spontaneous generation, some Christian [[Theology|theologians]] accepted the view. The Berber theologian and philosopher [[Augustine of Hippo]] discussed spontaneous generation in ''[[City of God (book)|The City of God]]'' and ''The Literal Meaning of Genesis'', citing Biblical passages such as "Let the waters bring forth abundantly the moving creature that hath life" ({{bibleverse||Genesis|1:20|KJV|}}) as decrees that would enable ongoing creation.<ref name="irisfry">{{cite book |last=Fry |first=Iris |title=The Emergence of Life on Earth |url=https://books.google.com/books?id=6KoRvUeUUuEC |chapter=Chapter 2: Spontaneous Generation – Ups and Downs |access-date=2009-01-21 |year=2000 |publisher=[[Rutgers University Press]] |isbn=978-0-8135-2740-6}}</ref>