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Chicken or the egg

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Revision as of 00:00, 23 May 2022 by 220.233.220.95 (talk) (→Ancient paradox: I answered it)(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff) Philosophical paradox This article is about the philosophical dilemma. For the dish combining both chicken meat and eggs, see oyakodon.
Illustration from Tacuina sanitatis, 14th century
A chick hatching from an egg

The chicken or the egg causality dilemma is commonly stated as the question, "which came first: the chicken or the egg?" The dilemma stems from the observation that all chickens hatch from eggs and all chicken eggs are laid by chickens. "Chicken-and-egg" is a metaphoric adjective describing situations where it is not clear which of two events should be considered the cause and which should be considered the effect, to express a scenario of infinite regress, or to express the difficulty of sequencing actions where each seems to depend on others being done first. Plutarch posed the question as a philosophical matter in his essay "The Symposiacs", written in the 1st century CE.

The chicken was first

Scientific resolutions

Although the question is typically used metaphorically, evolutionary biology provides literal answers, made possible by the Darwinian principle that species evolve over time, and thus that chickens had ancestors that were not chickens, similar to a view expressed by the Greek philosopher Anaximander when addressing the paradox.

If the question refers to eggs in general, the egg came first. The first amniote egg—that is, a hard-shelled egg that could be laid on land, rather than remaining in water like the eggs of fish or amphibians—appeared around 312 million years ago. In contrast, chickens are domesticated descendants of red junglefowl and probably arose little more than eight thousand years ago, at most.

If the question refers to chicken eggs specifically, the answer is still the egg, but the explanation is more complicated. The process by which the chicken arose through the interbreeding and domestication of multiple species of wild jungle fowl is poorly understood, and the point at which this evolving organism became a chicken is a somewhat arbitrary distinction. Whatever criteria one chooses, an animal nearly identical to the modern chicken (i.e., a proto-chicken) laid a fertilized egg that had DNA making it a modern chicken due to mutations in the mother's ovum, the father's sperm, or the fertilised zygote.

It has been suggested that the actions of a protein found in modern chicken eggs may make the answer different. In the uterus, chickens produce ovocleidin-17 (OC-17), which causes the formation of the thickened calcium carbonate shell around their eggs. Because OC-17 is expressed by the hen and not the egg, the bird in which the protein first arose, though having hatched from a non-reinforced egg, would then have laid the first egg having such a reinforced shell: the chicken would have preceded this first 'modern' chicken egg. However, the presence of OC-17 or a homolog in other species, such as turkeys and finches suggests that such eggshell-reinforcing proteins are common to all birds, and thus long predate the first chickens.

See also

References

  1. "Essays and Miscellanies, by Plutarch". Project Gutenberg. Retrieved 2020-07-07.
  2. O'Brien, Carl Séan (2015). The Demiurge in Ancient Thought. Cambridge, England: Cambridge University Press. p. 106. ISBN 978-1-107-07536-8.
  3. ^ Cite error: The named reference Fabry was invoked but never defined (see the help page).
  4. Cite error: The named reference paradox was invoked but never defined (see the help page).
  5. Benton, Michael J.; Donoghue, Philip C. J. (2007-01-01). "Paleontological Evidence to Date the Tree of Life". Molecular Biology and Evolution. 24 (1): 26–53. doi:10.1093/molbev/msl150. ISSN 0737-4038. PMID 17047029.
  6. Miao, Y-W; Peng, M-S; Wu, G-S; Ouyang, Y-N; Yang, Z-Y; Yu, N; Liang, J-P; Pianchou, G; Beja-Pereira, A (2012-12-05). "Chicken domestication: an updated perspective based on mitochondrial genomes". Heredity. 110 (3): 277–282. doi:10.1038/hdy.2012.83. ISSN 1365-2540. PMC 3668654. PMID 23211792.
  7. Sorensen, Roy A. (1992). "The Egg came before the chicken". Mind. 101 (403): 541–542. doi:10.1093/mind/101.403.541.
  8. Breyer, Melissa (2013-02-11). "Finally answered! Which came first, the chicken or the egg?". Mother Nature Network. Retrieved 2017-07-11.
  9. ^ Zushi, Yo (27 February 2017). "Which came first: the chicken or the egg?". NewStatesman.com.
  10. ^ "Which came first, the chicken or the egg? British scientists claim to have solved the mystery". NBCnews.com. 14 July 2010.
  11. Mann, Karlheinz; Mann, Matthias (2013). "The proteome of the calcified layer organic matrix of turkey (Meleagris gallopavo) eggshell". Proteome Sci. 11 (1): 40. doi:10.1186/1477-5956-11-40. PMC 3766105. PMID 23981693.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  12. Mann, Karlheinz (2015). "The calcified eggshell matrix proteome of a songbird, the zebra finch (Taeniopygia guttata)". Proteome Sci. 13: 29. doi:10.1186/s12953-015-0086-1. PMC 4666066. PMID 26628892.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  13. Hincke, Maxwell T.; Nys, Yves; Gautron, Joel (2010). "The Role of Matrix Proteins in Eggshell Formation". The Journal of Poultry Science. 47 (3): 208–219. doi:10.2141/jpsa.009122.

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