Death

=== Natural selection ===
{{Main|Competition (biology)|Natural selection}}

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 |issn=1936-6434 |s2cid=4508223}}</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 |url=https://link.springer.com/article/10.1007/BF02984069 |journal=[[Journal of Genetics]] |volume=55 |issue=3 |pages=511–524 |doi=10.1007/BF02984069 |s2cid=32233460 |via=SpringerLink |access-date=16 February 2023 |archive-date=17 August 2023 |archive-url=https://web.archive.org/web/20230817195526/https://link.springer.com/article/10.1007/BF02984069 |url-status=live }}</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 |issn=0027-8424 |pmc=388623 |pmid=4528606 |doi-access=free}}</ref>