Editing Hierarchy (section)

=== Biology ===
{{Main|Biological organisation#Fundamentals}}

Empirically, when we observe in nature a large proportion of the (complex) biological systems, they exhibit hierarchic structure.<ref>{{Cite journal |last=Simon |first=Herbert A. |date=1962 |title=The Architecture of Complexity |url=https://www.jstor.org/stable/985254 |journal=Proceedings of the American Philosophical Society |volume=106 |issue=6 |pages=467–482 |jstor=985254 |issn=0003-049X |access-date=2022-06-24 |archive-date=2022-06-24 |archive-url=https://web.archive.org/web/20220624110921/https://www.jstor.org/stable/985254 |url-status=live }}</ref> On theoretical grounds we could expect complex systems to be hierarchies in a world in which complexity had to evolve from simplicity.<ref>{{Cite web |title=Artificial Intelligence - foundations of computational agents -- 2 Agent Architectures and Hierarchical Control |url=https://artint.info/html/ArtInt_33.html |access-date=2022-06-24 |website=artint.info |archive-date=2022-07-04 |archive-url=https://web.archive.org/web/20220704035951/http://artint.info/html/ArtInt_33.html |url-status=live }}</ref> [[Systems theory|System]] hierarchies analysis performed in the 1950s,<ref>{{harvnb|Evans|1951}}</ref><ref>{{harvnb|Evans|1956}}</ref> laid the empirical foundations for a [[Branches of science|field]] that would become, from the 1980s, '''hierarchical ecology'''.<ref>{{harvnb|Margalef|1975}}</ref><ref>{{harvnb|O'Neill|1986}}</ref><ref>{{harvnb|Wicken|Ulanowicz|1988}}</ref><ref>{{harvnb|Pumain|2006}}</ref><ref>{{harvnb|Jordan|Jørgensen|2012}}</ref>

The theoretical foundations are summarized by [[thermodynamics]].
When [[biological systems]] are modeled as [[physical system]]s, in the most general abstraction, they are [[Thermodynamic system#Open system|thermodynamic open systems]] that exhibit [[self-organisation|self-organised]] behavior, and the [[Set theory|set/subset]] relations between [[dissipative structures]] can be characterized{{by whom|date=November 2021}} in a hierarchy.

Other hierarchical representations related to biology include [[ecological pyramids]] which illustrate energy flow or [[trophic levels]] in [[ecosystems]], and [[Taxonomy (general)|taxonomic]] hierarchies, including the [[Linnean classification]] scheme and [[phylogenetic trees]] that reflect inferred patterns of evolutionary relationship among living and extinct species.