Editing Death (section)

== In biology ==
{{Stages_of_death}}
[[File:Earthworm.jpg|thumb|[[Earthworm]]s are soil-dwelling detritivores.]]

Death plays a role in [[extinction]], which is generally considered to be the death of the last individual of a [[species]].<ref>{{cite journal |last1=Purvis |first1=Andy |last2=Jones |first2=Kate E. |last3=Mace |first3=Georgina M. |title=Extinction |journal=BioEssays |date=10 November 2000 |volume=22 |issue=12 |pages=1123–1133 |doi=10.1002/1521-1878(200012)22:12<1123::AID-BIES10>3.0.CO;2-C |pmid=11084628 }}</ref> After death, the remains of a former organism become part of the [[biogeochemical cycle]], during which animals may be [[necrophagy|consumed]] by a [[predator]] or a [[scavenger]].<ref>{{cite book |doi=10.1016/b0-12-226865-2/00032-8 |chapter=Biogeochemical Cycles |title=Encyclopedia of Biodiversity |date=2001 |last1=Falkowski |first1=Paul G. |pages=437–453 |isbn=978-0-12-226865-6 }}</ref> [[Organic material]] may then be further [[decomposition|decomposed]] by [[detritivore]]s, organisms that recycle [[detritus]], returning it to the environment for reuse in the [[food chain]], where these chemicals may eventually end up being consumed and assimilated into the cells of an organism.<ref>{{Cite book |last=Wetzel |first=Robert |title=Limnology: Lake and River Ecosystems |date= 2001 |publisher=Elsevierda |isbn=978-0-12-744760-5 |edition=3rd |page=700}}</ref> Examples of detritivores include [[earthworm]]s, [[woodlice]], and [[millipede]]s.<ref>{{Cite journal |last1=Lindsey-Robbins |first1=Josephine |last2=Vázquez-Ortega |first2=Angélica |last3=McCluney |first3=Kevin |last4=Pelini |first4=Shannon |date=December 13, 2019 |title=Effects of Detritivores on Nutrient Dynamics and Corn Biomass in Mesocosms |journal=Insects |volume=10 |issue=12 |page=453 |doi=10.3390/insects10120453 |pmid=31847249 |pmc=6955738 |doi-access=free }}</ref>

[[Microorganism]]s also play a vital role, raising the temperature of the decomposing matter as they break it down into yet simpler molecules.<ref>{{Cite journal |last1=Rousk |first1=Johannes |last2=Bengston |first2=Per |date=March 14, 2014 |title=Microbial regulation of global biogeochemical cycles |journal=Frontiers in Microbiology |volume=5 |page=103 |doi=10.3389/fmicb.2014.00103 |pmid=24672519 |pmc=3954078 |doi-access=free }}</ref> Not all materials need to be fully decomposed. [[Coal]], a [[fossil fuel]] formed over vast tracts of time in [[swamp]] ecosystems, is one example.<ref>{{Cite book |last=George |first=McGhee |title=Carboniferous Giants and Mass Extinction: The Late Paleozoic Ice Age World |publisher=Columbia University Press |year=2018 |isbn=978-0-231-18097-9 |pages=98–102}}</ref>

=== Natural selection ===
{{Main|Competition (biology)|Natural selection}}
[[File:Desecased Cowbird on the street.jpg|thumb|Dead [[Scrub blackbird]] in Lima, Perú]]
The contemporary [[history of evolutionary thought|evolutionary theory]] sees death as an important part of the process of [[natural selection]]. It is considered that organisms less [[adaptation|adapted]] to their environment are more likely to die, having produced fewer offspring, thereby reducing their contribution to the [[gene pool]]. Their genes are thus eventually bred out of a population, leading at worst to [[extinction]] and, more positively, making the process possible, referred to as [[speciation]]. Frequency of [[biological reproduction|reproduction]] plays an equally important role in determining species survival: an organism that dies young but leaves numerous offspring displays, according to [[Charles Darwin|Darwinian]] criteria, much greater [[Darwinian fitness|fitness]] than a long-lived organism leaving only one.<ref>{{Cite journal |last=Gregory |first=T. Ryan |date=June 2009 |title=Understanding Natural Selection: Essential Concepts and Common Misconceptions |journal=Evolution: Education and Outreach |language=en |volume=2 |issue=2 |pages=156–175 |doi=10.1007/s12052-009-0128-1 |doi-access=free }}</ref><ref>{{Cite journal |last=Haldane |first=J. B. S. |author-link=J. B. S. Haldane |date=December 1957 |title=The cost of natural selection |journal=[[Journal of Genetics]] |volume=55 |issue=3 |pages=511–524 |doi=10.1007/BF02984069 }}</ref>

Death also has a role in [[Competition (biology)|competition]], where if a species out-competes another, there is a risk of death for the population, especially in the case where they are directly fighting over resources.<ref>{{Cite journal |last1=Case |first1=Ted J. |last2=Gilpin |first2=Micheal E. |date=August 1, 1974 |title=Interference Competition and Niche Theory |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=71 |issue=8 |pages=3073–3077 |bibcode=1974PNAS...71.3073C |doi=10.1073/pnas.71.8.3073 |pmc=388623 |pmid=4528606 |doi-access=free}}</ref>

=== Evolution of aging and mortality ===
{{Main|Evolution of ageing}}

Inquiry into the evolution of aging aims to explain why so many living things and the vast majority of animals weaken and die with age. However, there are exceptions, such as ''[[Hydra (genus)|Hydra]]'' and the jellyfish ''[[Turritopsis dohrnii]]'', which research shows to be [[biological immortality|biologically immortal]].<ref>{{Cite web |last=National Institute on Aging |date=2020 |title=The National Institute on Aging: Strategic Directions for Research, 2020–2025 |url=https://www.nia.nih.gov/about/aging-strategic-directions-research |access-date=February 16, 2023 |website=National Institute on Aging |archive-date=4 June 2020 |archive-url=https://web.archive.org/web/20200604212742/https://www.nia.nih.gov/about/aging-strategic-directions-research |url-status=live }}</ref>

Organisms showing only [[asexual reproduction]], such as bacteria, some [[protist]]s, like the [[euglenoid]]s and many [[amoebozoan]]s, and [[unicellular]] organisms with [[sexual reproduction]], [[Colony (biology)|colonial]] or not, like the [[Volvocales|volvocine]] algae ''[[Pandorina]]'' and ''[[Chlamydomonas]],'' are "immortal" at some extent, dying only due to external hazards, like being eaten or meeting with a fatal accident. In [[multicellular]] organisms and also in [[multinucleate]] [[ciliates]]<ref>{{cite book |doi=10.1093/acprof:oso/9780199657148.003.0002 |chapter=The diversity of sexual cycles |title=The Evolution of Sex Determination |date=2014 |last1=Beukeboom |first1=Leo W. |last2=Perrin |first2=Nicolas |pages=18–36 |isbn=978-0-19-965714-8 }}</ref> with a [[Weismann barrier|Weismannist development]], that is, with a division of labor between mortal [[somatic cells|somatic (body) cells]] and "immortal" [[germ cell|germ (reproductive) cells]], death becomes an essential part of life, at least for the somatic line.<ref name=Gilbert>{{cite book|last=Gilbert |first=S.F. |year=2003 |title=Developmental biology |edition=7th |place=Sunderland, Mass |publisher=Sinauer Associates |pages=34–35 |isbn=978-0-87893-258-0}}</ref>

The ''[[Volvox]]'' algae are among the simplest organisms to exhibit that division of labor between two completely different cell types, and as a consequence, include the death of somatic line as a regular, genetically regulated part of its [[Biological life cycle|life history]].<ref name=Gilbert /><ref>{{cite journal|doi=10.1007/s00497-010-0158-4 |pmid=21174128 |pmc=3098969 |title=Evolution of reproductive development in the volvocine algae |last=Hallmann |first=A. |journal=Sexual Plant Reproduction |date=June 2011 |volume=24 |issue=2 |pages=97–112}}</ref>

=== Grief in animals ===
Animals have sometimes shown grief for their partners or "friends". When two [[chimpanzee]]s form a bond together, [[Intimate relationship|sexual]] or [[Platonic love|not]], and one of them dies, the surviving chimpanzee will show signs of grief, ripping out their hair in anger and starting to cry; if the body is removed, they will resist, they will eventually go quiet when the body is gone, but upon seeing the body again, the chimp will return to a violent state.<ref>{{Cite journal |last=Brown |first=Arthur E. |date=March 1879 |title=Grief in the Chimpanzee |journal=The American Naturalist |volume=13 |issue=3 |pages=173–175 |doi=10.1086/272298 |jstor=2448772 |bibcode=1879ANat...13..173B |jstor-access=free}}</ref>

Furthermore, anthropologist Barbara J. King has suggested that one way to evaluate the expression of grief in animals is to look for altered behaviors such as social withdrawal, disrupted eating or sleeping, expression of affect, or increased stress reactions in response to the death of a family member, mate, or friend.<ref name=":1">{{cite book |last1=King |first1=Barbara J. |title=How Animals Grieve |date=2014 |publisher=University of Chicago Press |isbn=978-0-226-15520-3 }}{{page needed|date=November 2024}}</ref> These criteria do not assume the ability to anticipate death, understand its finality, or experience emotions equivalent to those of humans, but at the same time do not rule out the possibility of those abilities existing in some animals or that different kinds of emotional experiences might constitute grief.<ref>{{cite journal |last1=King |first1=Barbara J |title=Animal mourning: Précis of How animals grieve (King 2013) |journal=Animal Sentience |date=2016 |volume=1 |issue=4 |doi=10.51291/2377-7478.1010 |doi-access=free }}</ref> Based on these criteria, King gives examples of observed potential mourning behaviors in animals such as cetaceans, apes and monkeys, elephants, domesticated animals (including dogs, cats, rabbits, horses, and farmed animals), giraffes, peccaries, donkeys, prairie voles, and some species of birds.<ref name=":1" /><ref>{{Cite journal |last=King |first=Barbara J. |date=2019 |title=The ORCA'S SORROW |journal=Scientific American |volume=320 |issue=3 |pages=30–35 |doi=10.1038/scientificamerican0319-30 |jstor=27265108 |pmid=39010370 }}</ref>

===Cell death===
{{excerpt|Cell death}}