Editing Modularity (section)

===Modularity in biology===
As in some of the other disciplines, the term modularity may be used in multiple ways in biology. For example, it may refer to organisms that have an indeterminate structure wherein modules of various complexity (e.g., leaves, twigs) may be assembled without strict limits on their number or placement. Many plants and [[Sessility (zoology)|sessile]] (immobile) [[invertebrate]]s of the [[benthic zone]]s  demonstrate this type of modularity (by contrast, many other organisms have a determinate structure that is predefined in [[embryogenesis]]).<ref>Andrews, J. 1998. [https://www.annualreviews.org/doi/abs/10.1146/annurev.micro.52.1.105 Bacteria as modular organisms]. ''[[Annual Review of Microbiology]]'', 52:105–126.</ref> The term has also been used in a broader sense in biology to refer to the reuse of [[homologous structure]]s across individuals and species. Even within this latter category, there may be differences in how a module is perceived. For instance, evolutionary biologists may focus on the module as a [[morphology (biology)|morphological]] component (subunit) of a whole organism, while [[developmental biologist]]s may use the term module to refer to some combination of lower-level components (e.g., [[gene]]s) that are able to act in a unified way to perform a function.<ref>Bolker, J. A. 2000. [https://academic.oup.com/icb/article-pdf/40/5/770/369180/i0003-1569-040-05-0770.pdf "Modularity in development and why it matters to Evo-Devo"]. ''American Zoologist'', 40: 770–776.</ref> In the former, the module is perceived a basic component, while in the latter the emphasis is on the module as a collective.

Biology scholars have provided a list of features that should characterize a module (much as Fodor did in ''The Modularity of Mind''<ref name=fodor1983>Fodor, J. 1983. ''The Modularity of Mind''. Cambridge, Massachusetts: MIT Press.</ref>). For instance, Rudy Raff<ref name=Raff>Raff, R. A. 1996. ''The Shape of Life''. Chicago: Chicago University Press.</ref> provides the following list of characteristics that developmental modules should possess:
# discrete genetic specification
# hierarchical organization
# interactions with other modules
# a particular physical location within a developing organism
# the ability to undergo transformations on both developmental and evolutionary time scales

To Raff's mind, developmental modules are "dynamic entities representing localized processes (as in morphogenetic fields) rather than simply incipient structures&nbsp;... (...&nbsp;such as organ rudiments)".<ref name=Raff/>{{rp|326}} Bolker, however, attempts to construct a definitional list of characteristics that is more abstract, and thus more suited to multiple levels of study in biology. She argues that:
# A module is a biological entity (a structure, a process, or a pathway) characterized by more internal than external integration
# Modules are biological individuals<ref>Hull, D. L. 1980. [http://www.joelvelasco.net/teaching/167/Hull%201980%20-%20Individuality%20and%20Selection.pdf Individuality and selection]. Annual Review of Ecology and Systematics, 11:311–332</ref><ref>Roth, V. L. 1991. [https://onlinelibrary.wiley.com/doi/pdf/10.1046/j.1420-9101.1991.4020167.x Homology and hierarchies: Problems solved and unresolved]. Journal of Evolutionary Biology, 4:167–194</ref> that can be delineated from their surroundings or context, and whose behavior or function reflects the integration of their parts, not simply the arithmetical sum. That is, as a whole, the module can perform tasks that its constituent parts could not perform if dissociated.
# In addition to their internal integration, modules have external connectivity, yet they can also be delineated from the other entities with which they interact in some way.

Another stream of research on modularity in biology that should be of particular interest to scholars in other disciplines is that of [[Günter Wagner]] and [[Lee Altenberg]]. Altenberg's work,<ref>Altenberg, L. 1995. [http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.39.3876&rep=rep1&type=pdf "Genome growth and the evolution of the genotype-phenotype map"]. In ''Evolution and Biocomputation: Computational Models of Evolution'', ed. Wolfgang Banzhaf and Frank H. Eeckman. Lecture Notes in Computer Science vol. 899. Springer-Verlag, pp. 205–259.</ref> Wagner's work,<ref>Wagner, G. 1996. "Homologues, natural kinds and the evolution of modularity". ''American Zoologist'', 36:36–43.</ref> and their joint writing<ref>Wagner, G. and Altenberg, L. 1996a. "Perspective: complex adaptations and the evolution of evolvability". ''Evolution'', 50:967–976.</ref> explores how natural selection may have resulted in modular organisms, and the roles modularity plays in evolution. Altenberg's and Wagner's work suggests that modularity is both the result of evolution, and facilitates evolution—an idea that shares a marked resemblance to work on modularity in technological and organizational domains.