facis de necessitate virtute .




“Pleiotropy” is a term almost exclusive to genetics where it refers to the phenomenon of a single gene affecting multiple traits.  Paaby & Rockman (2013)[1] point out that “At its essence, pleiotropy implies a mapping from one thing at the genetic level to multiple things at a phenotypic level. [and] The natures of the things differ in different contexts.” 


“The term pleiotropy is derived from the Greek words pleio, which means “many,” and tropic, which means “affecting.” Genes that affect multiple, apparently unrelated, phenotypes are thus called pleiotropic genes” …. (Pleiotropy should not be confused with polygenic traits, in which multiple genes converge to result in a single phenotype) (examples of genetic pleiotropy).  


This is, however a rich concept that can used fruitfully to think about connections in general:



W. H. Auden once wrote that “Language is the mother, not the handmaiden, of thought; words will tell you things you never thought or felt before” (quoted in A&O notes).  


This extraordinary power of words may be attributable to its pleiotropy (see “The Problem with Words”).  Every word exits in mind at the center of an intuitive mind-map in which more-or-less of all it might refer to are perceived (almost) simultaneously.


IS a WORD a kind of GENE?   Like genes, they have consequences which constitute their meaning.  Can I say that words are pleiotropic… have multiple meanings any one of which can—like an evolutionarily adaptive trait—strike out in a new direction when their environment changes?   (adapted from https://neilgreenberg.com/ao-words/ ) 


WORDS have MEANING—and like everything else we discuss in A&O meaning relies on connectedness:  for example, the words poets choose have more-or-less meaning.  Robert Pogue Harrison reviewed a translation of Canti by Giacomo Leopardi (in NYRB February 10, 2011) & commented on a very significant element for all writers to consider:

An …”exasperating feature of Leopardi’s poetry for the English translator is its systematic deployment of common words. Leopardi sheds light on this practice in his notebooks, where he draws a distinction between what he called parole and termini, words and terms. Parole are words that have been in circulation through the ages and contain a number of associations, connotations, and latent meanings. Termini, by contrast, are unhistorical, univocal, often technical terms that do not connote, only denote. By preserving their metaphorical and sensory history, parole come with a host of “accessory images,” whereas termini “offer only a single idea of the object signified.” Leopardi elaborates: “If I call a plant or animal by the Linnaean name, I have aroused none of these [accessory] images, even though the thing itself is clearly indicated.”   

                                                            [See A&O notes on connections and ambiguity]






Pleiotropy also discussed in Molecular Pathology:  as in Christine M. Koellner, … W. Edward HighsmithJr., (2020, Essential Concepts in Molecular Pathology (Second Edition),

[i] Perspectives: Anecdotal, Historical  and  Critical Commentaries on Genetics. One  Hundred Years of Pleiotropy: A Retrospective. Frank W. Stearns (2010)  Genetics 186:767–773. DOI: 10.1534/genetics.110.122549  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2975297/

“Pleiotropy is defined as the phenomenon in which a single locus affects two or more distinct phenotypic traits. The term was formally introduced into the literature by the German geneticist Ludwig Plate in 1910, 100 years ago. Pleiotropy has had an important influence on the fields of physiological and medical genetics as well as on evolutionary biology. Different approaches to the study of pleiotropy have led to incongruence in the way that it is perceived and discussed among researchers in these fields. Furthermore, our understanding of the term has changed quite a bit since 1910, particularly in light of modern molecular data. This review traces the history of the term “pleiotropy” and reevaluates its current place in the field of genetics.”


[ii] The many faces of pleiotropy. Annalise B. Paaby and Matthew V. Rockman (2013) Trends Genet. Author manuscript; available in PMC 2014 Feb 1.Trends Genet. 2013 Feb; 29(2): 66–73.  Published online 2012 Nov 7. doi: 10.1016/j.tig.2012.10.010  PMID: 23140989  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3558540/   

“Pleiotropy is the well-established phenomenon of a single gene affecting multiple traits. It has long played a central role in theoretical, experimental, and clinical research in genetics, development, molecular biology, evolution, and medicine. In recent years, genomic techniques have brought data to bear on fundamental questions about the nature and extent of pleiotropy. However, these efforts are plagued by conceptual difficulties derived from disparate meanings and interpretations of pleiotropy. Here, we describe distinct uses of the pleiotropy concept and explain the pitfalls associated with applying empirical data to them. We conclude that for any question about the nature or extent of pleiotropy, the appropriate answer is always, “What do you mean?”