Editing Wilhelm Johannsen

{{short description|Danish botanist and geneticist}}
{{Use dmy dates|date=May 2024}}
{{Infobox scientist
|name              = Wilhelm Ludvig Johannsen
|image             = Wilhelm Johannsen 1857-1927.jpg
|birth_date        = {{birth date|1857|02|03|df=y}}
|birth_place       = [[Elsinore]], [[Denmark]]
|death_date        = {{death date and age|1927|11|11|1857|02|03|df=y}}
|death_place       = [[Copenhagen]], Denmark
|field             = [[Genetics]]<br/>[[Plant physiology]]
|work_institution  = [[University of Copenhagen]]
|alma_mater        = [[University of Copenhagen]]
|doctoral_advisor  =
|doctoral_students =
|known_for         = proving the constancy of the [[genome]]<br/>Coining [[gene]], [[genotype]] and [[phenotype]]
|prizes            =
|footnotes         =
}}

'''Wilhelm Johannsen''' (3 February 1857 – 11 November 1927) was a [[Denmark|Danish]] pharmacist, [[botanist]], [[Plant physiology|plant physiologist]], and [[geneticist]]. He is best known for coining the terms [[gene]], [[phenotype]] and [[genotype]], and for his 1903 [[Mutationism#Johannsen.27s .22pure line.22 experiments.2C 1903|"pure line" experiments]] in [[genetics]].

==Biography==
Johannsen was born in [[Copenhagen]].  While very young, he was apprenticed to a [[pharmacist]] and worked in [[Denmark]] and Germany beginning in 1872 until passing his pharmacist's exam in 1879. In 1881, he became assistant in the chemistry department at the [[Carlsberg Laboratory]] under the chemist [[Johan Kjeldahl]]. Johannsen studied the [[metabolism]] of [[dormancy]] and [[germination]] in [[seed]]s, [[tuber]]s and [[bud]]s. He showed that [[dormancy]] could be broken by various [[anesthetic]] compounds, such as [[diethyl ether]] and [[chloroform]].

In 1892, he was appointed lecturer at [[Royal Veterinary and Agricultural University]] and later became professor of [[botany]] and [[plant physiology]]. He taught plant physiology.<ref>[[Eugenius Warming|Warming, Eug.]] & W. Johannsen (1895) Den almindelige Botanik (General Botany): En Lærebog, nærmest til Brug for Studerende og Lærere. 3rd edn, [[Copenhagen|Kjøbenhavn]]. 4th edn by Warming and Johannsen 1900-01). German edn 1907-09: Lehrbuch der allgemeinen Botanik (from the 4th edn, by E. P. Meinecke). Berlin, Borntraeger. 667 pp.</ref> His best-known research concerned so-called ''pure lines'' of the self-fertile [[common bean]]. He was able to show that even in [[population]]s [[homozygote|homozygous]] for all traits, i.e. without genetic variation, seed size followed a [[normal distribution]]. This was attributable to resource provision to the mother plant and to the position of seeds in [[Legume|pod]]s and of pods on the plant. This led him to coin the terms ''[[phenotype]]'' and ''[[genotype]]''.

Johannsen's findings led him to oppose contemporary [[Darwinism|Darwinists]], most notably [[Francis Galton]] and [[Karl Pearson]], who held the occurrence of [[normal distribution|normal distributed]] trait variation in [[population]]s as proof of gradual genetic variation on which selection could act.<ref>{{cite journal | last1 = Roll-Hansen | first1 = Nils | year = 1979 | title = The Genotype Theory of Wilhelm Johannsen and its Relation to Plant Breeding and the Study of Evolution | journal = Centaurus | volume = 22 | issue = 3| pages = 201–235 | doi = 10.1111/j.1600-0498.1979.tb00589.x | bibcode = 1979Cent...22..201R }}</ref> Only with the [[Modern synthesis (20th century)|modern synthesis]], was it established that variation needed to be [[heritable]] to act as the raw material for [[Selection (biology)|selection]].

He created the terms ''[[phenotype]]'' and ''[[genotype]]'', first using them in his book in German as ''Elemente der exakten Erblichkeitslehre'' (Elements of the exact theory of heredity).<ref>{{cite book |last1=Johannsen |first1=W. |title=Elemente der exakten Erblichkeitslehre |trans-title=Elements of the exact theory of heredity |date=1909 |publisher=Gustav Fischer |location=Jena, Germany |page=123 |url=https://www.biodiversitylibrary.org/item/15717#page/133/mode/1up |language=German}}  Johannsen distinguished between an organism's outward appearance (which he designated as its "phenotype") and its inherent genetic heritage (which he designated as its "genotype").  He stressed that an organism's appearance need not correspond exactly to its genetic heritage.  So on p. 123 he defines "phenotype":  ''"Darum könnte man den statistisch hervortretenden Typus passend als Erscheinungstypus bezeichnen oder, kurz und klar, als "Phaenotypus". 1) … Ein gebener Phaenotypus mag Ausdruck einer biologischen Einheit sein; er braucht es aber durchaus nicht zu sein.  1) Von φαίν-ομαι, scheinen."''  (Therefore one could designate the statistically prominent type appropriately as a type of appearance or, clearly and concisely, as a "phenotype".  1)  … A given phenotype may be an expression of a biological unit; but it definitely need not be so.  1) From φαίν-ομαι, to appear.)</ref><ref>{{cite book |last1=Johannsen |first1=W. |title=Elemente der exakten Erblichkeitslehre |trans-title=Elements of the exact theory of heredity |date=1909 |publisher=Gustav Fischer |location=Jena, Germany |page=130 |url=https://www.biodiversitylibrary.org/item/15717#page/140/mode/1up |language=German}}  Johannsen coins the term "genotype" on p. 130, where he stresses the distinction between phenotype and genotype:  ''"Die Art, wie die Phaenotypen sich manifestieren, … der abgeleitete Begriff genotypischer Unteschied wird uns aber vielfach von Nutzen sein."''   (The way that the phenotype manifests itself, whether it shows itself by traits that [can be] examined qualitatively or quantitatively, says absolutely nothing beforehand about the genes.  Very conspicuous phenotypic differences could show themselves where no genotypic difference is present, and there are also cases where in the case of genotypic variety, the phenotypes are alike.  Thus it is precisely of the greatest importance to separate clearly the concept of phenotype (a type of appearance) from the concept of genotype (one might say a type of plan).  We will admittedly not be able to operate with this latter concept  – a genotype just does not appear in pure form; the derived concept of a genotypic difference will, however, often be of use to us.)</ref> This book was based in large part on ''Om arvelighed i samfund og i rene linier'' ("On heredity in society and in pure lines")<ref>Johannsen, W. (1903) Om arvelighed i samfund og i rene linier. Oversigt over det [[Kongelige Danske Videnskabernes Selskab]]s Forhandlinger, vol. 3: 247-270. German ed. ''Erblichkeit in Populationen und in reinen Linien'' (1903) Gustav Fischer, Jena. [http://caliban.mpiz-koeln.mpg.de/~stueber/johannsen/erblichkeit/index.html Scanned full text.] {{Webarchive|url=https://web.archive.org/web/20090530140510/http://caliban.mpiz-koeln.mpg.de/~stueber/johannsen/erblichkeit/index.html |date=30 May 2009 }}</ref> and in his book ''Arvelighedslærens Elementer''.<ref>Johannsen, W.L. (1905) Arvelighedslærens elementer (The Elements of Heredity). Copenhagen.</ref> It was in this book Johannsen also introduced the term ''[[gene]]''.<ref>{{cite book |last1=Johannsen |first1=W. |title=Elemente der exakten Erblichkeitslehre |trans-title=Elements of the exact theory of heredity |date=1909 |publisher=Gustav Fischer |location=Jena, Germany |page=124 |url=https://www.biodiversitylibrary.org/item/15717#page/134/mode/1up |language=German}}  From p. 124:  ''"Dieses "etwas" in den Gameten bezw. in der Zygote, … – kurz, was wir eben Gene nennen wollen – bedingt sind."''  (This "something" in the gametes or in the zygote, which has crucial importance for the character of the organism, is usually called by the quite ambiguous term ''Anlagen'' [primordium, from the German word ''Anlage'' for "plan, arrangement; rough sketch"].  Many other terms have been suggested, mostly unfortunately in closer connection with certain hypothetical opinions.  The word "pangene", which was introduced by Darwin, is perhaps used most frequently in place of ''Anlagen''.  However, the word "pangene" was not well chosen, as it is a compound word containing the roots ''pan'' (the neuter form of Πας all, every) and ''gen'' (from γί-γ (ε)ν-ομαι, to become).  Only the meaning of this latter [i.e., ''gen''] comes into consideration here; just the basic idea – [namely,] that a trait in the developing organism can be determined or is influenced by "something" in the gametes – should find expression.  No hypothesis about the nature of this "something" should be postulated or supported by it.  For that reason it seems simplest to use in isolation the last syllable ''gen'' from Darwin's well-known word, which alone is of interest to us, in order to replace, with it, the poor, ambiguous word ''Anlage''.  Thus we will say simply "gene" and "genes" for "pangene" and "pangenes".  The word gene is completely free of any hypothesis; it expresses only the established fact that in any case many traits of the organism are determined by specific, separable, and thus independent "conditions", "foundations", "plans" – in short, precisely what we want to call genes.)</ref> This term was coined in opposition to the then common ''pangene'' that stemmed from [[Charles Darwin|Darwin's]] theory of [[pangenesis]]. The book became one of the founding texts of genetics.

Also in 1905, Johannsen was appointed professor of [[plant physiology]] at the [[University of Copenhagen]], becoming vice-chancellor in 1917. In December 1910, Johannsen was invited to give an address before the [[American Society of Naturalists]]. This talk was printed in the [[American Naturalist]].<ref>{{Cite journal | doi = 10.1086/279202 | title = The Genotype Conception of Heredity | journal = The American Naturalist | volume = 45 | issue = 531 | pages = 129–59 | year = 1911 | last1 = Johannsen | first1 = W. | jstor=2455747 | pmid = 24691957 | pmc = 4258772 }}</ref> In 1911, he was invited to give a series of four lectures at [[Columbia University]].<ref>{{cite journal | last1 = Anon | year = 1911 | title = Professor Johannsen's Columbia Lectures | journal = Science | volume = 34 | issue = 876| page = 484 | jstor=1637692 | doi=10.1126/science.34.876.484| pmid = 17793952 }}</ref>

Johannsen was a corresponding member of the [[Academy of Natural Sciences of Philadelphia]] (elected 1915). He was elected to the [[American Philosophical Society]] in 1916.<ref>{{Cite web |title=APS Member History |url=https://search.amphilsoc.org/memhist/search?creator=Wilhelm+L.+Johannsen&title=&subject=&subdiv=&mem=&year=&year-max=&dead=&keyword=&smode=advanced |access-date=2023-10-23 |website=search.amphilsoc.org}}</ref>

==References==
{{Reflist}}

==Sources==
*Anker, Jean (1932) Wilhelm Johannsen, pp.&nbsp;177–180 in: Meisen, V. Prominent Danish Scientists through the Ages. University Library of Copenhagen 450th Anniversary. Levin & Munksgaard, Copenhagen.
* Roll-Hansen, Nils (1983) The Death of Spontaneous Generation and the Birth of the Gene: Two Case Studies of Relativism. Social Studies of Science 13 (4): 481–519. {{JSTOR|284846}}
*Kim, Kyung-Man (1991) On the Reception of Johannsen's Pure Line Theory: Toward a Sociology of Scientific Validity. Social Studies of Science 21 (4): 649–679. {{JSTOR|285343}}

==External links==
*[https://web.archive.org/web/20070905100436/http://www.wjc.ku.dk/ Wilhelm Johannsen Centre for Functional Genome Research]
*[https://web.archive.org/web/20030620045935/http://www.wjc.ku.dk/wilhelm/index.php?subpage=gallery Image gallery]
*[https://web.archive.org/web/20070622123242/http://www.wjc.ku.dk/library/video/original.avi 6 min silent movie showing Johannsen in action as teacher and scientist]

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[[Category:20th-century Danish botanists]]
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[[Category:Agriculture educators]]
[[Category:Danish science writers]]
[[Category:University of Copenhagen alumni]]
[[Category:Academic staff of the University of Copenhagen]]
[[Category:People from Helsingør]]
[[Category:Carlsberg Laboratory staff]]
[[Category:Plant physiologists]]
[[Category:Danish geneticists]]
[[Category:Rectors of the University of Copenhagen]]
[[Category:19th-century Danish botanists]]
[[Category:Members of the Royal Society of Sciences in Uppsala]]
[[Category:International members of the American Philosophical Society]]