Editing Pangenesis (section)

== Early history ==

Pangenesis was similar to ideas put forth by [[Hippocrates]], [[Democritus]] and other pre-Darwinian scientists in proposing that the whole of parental organisms participate in heredity (thus the prefix ''pan'').<ref name="Zirkle 1935">{{cite journal |last1=Zirkle |first1=Conway |author-link=Conway Zirkle |year=1935 |title=The Inheritance of Acquired Characters and the Provisional Hypothesis of Pangenesis |journal=[[The American Naturalist]] |volume=69 |issue=724 |pages=417–445 |doi=10.1086/280617 |bibcode=1935ANat...69..417Z |s2cid=84729069 }}</ref> Darwin wrote that Hippocrates' pangenesis was "almost identical with mine—merely a change of terms—and an application of them to classes of facts necessarily unknown to the old philosopher."<ref name="Deichmann 2010">Deichmann, Ute. (2010). ''Darwinism, Philosophy, and Experimental Biology''. Springer. pp. 41-42. {{ISBN|978-90-481-9901-3}}</ref>

The historian of science [[Conway Zirkle]] wrote that:

{{blockquote |The hypothesis of pangenesis is as old as the belief in the inheritance of acquired characters. It was endorsed by [[Hippocrates]], [[Democritus]], [[Galen]], [[Clement of Alexandria]], [[Lactantius]], [[St. Isidore of Seville]], [[Bartholomeus Anglicus]], [[St. Albert the Great]], [[St. Thomas of Aquinas]], [[Pietro de' Crescenzi|Peter of Crescentius]], [[Paracelsus]], [[Jerome Cardan]], [[Levinus Lemnius]], [[Nicolas Venette|Venette]], [[John Ray]], [[Georges-Louis Leclerc, Comte de Buffon|Buffon]], [[Charles Bonnet|Bonnet]], [[Pierre Louis Maupertuis|Maupertuis]], [[Albrecht von Haller|von Haller]] and [[Herbert Spencer]].<ref name="Zirkle 1935"/>}}

Zirkle demonstrated that the idea of inheritance of acquired characteristics had become fully accepted by the 16th century and remained immensely popular through to the time of Lamarck's work, at which point it began to draw more criticism due to lack of hard evidence.<ref name="Zirkle 1935"/> He also stated that pangenesis was the only scientific explanation ever offered for this concept, developing from Hippocrates' belief that "the semen was derived from the whole body."<ref name="Zirkle 1935"/> In the 13th century, pangenesis was commonly accepted on the principle that semen was a refined version of food unused by the body, which eventually translated to 15th and 16th century widespread use of pangenetic principles in medical literature, especially in gynecology.<ref name="Zirkle 1935"/> Later pre-Darwinian important applications of the idea included hypotheses about the origin of the differentiation of races.<ref name="Zirkle 1935"/>

A theory put forth by [[Pierre Louis Maupertuis]] in 1745 called for particles from both parents governing the attributes of the child, although some historians have called his remarks on the subject cursory and vague.<ref>{{cite book |author=Mayr, Ernst |author-link=Ernst Mayr |date=1981 |title=The Growth of Biological Thought |publisher=Harvard University Press |isbn=978-0674364462 |pages=328, 646}}</ref><ref name=":2">{{Cite book |title=Charles Darwin: A Scientific Biography |last=de Beer |first=Gavin |publisher=Doubleday & Company |year=1965 |location=Garden City, New York |pages=205}}</ref>

In 1749, the French naturalist [[Georges-Louis Leclerc, Comte de Buffon]] developed a hypothetical system of heredity much like Darwin's pangenesis, wherein 'organic molecules' were transferred to offspring during reproduction and stored in the body during development.<ref name=":2"/><ref>Hull, David L. (1988). ''Science as a Process: An Evolutionary Account of the Social and Conceptual Development of Science''. University of Chicago Press. p. 86. {{ISBN |0-226-36051-2}} "As Darwin was to discover many years later, Buffon had devised a system of heredity not all that different from his own theory of pangenesis."</ref> Commenting on Buffon's views, Darwin stated, "If Buffon had assumed that his organic molecules had been formed by each separate unit throughout the body, his view and mine would have been very closely similar."<ref name="Zirkle 1935"/>

In 1801, [[Erasmus Darwin]] advocated a hypothesis of pangenesis in the third edition of his book ''[[Zoonomia]]''.<ref>Deichmann, Ute. (2010). ''Darwinism, Philosophy, and Experimental Biology''. Springer. p. 42. {{ISBN |978-90-481-9901-3}} "Among the other authors were Buffon, who proposes "organic molecules" with affinities to various organs, and, in particular, Erasmus Darwin, who in 1801 anticipated his grandson's concept of pangenesis, suggesting that small particles were given off by parts of the bodies of both parents; and that they are circulated in the blood, ending in the sexual organs from where they could be combined during reproduction in order to form the nucleus of an offspring."</ref> In 1809, [[Jean-Baptiste Lamarck]] in his ''[[Philosophie Zoologique]]'' put forth evidence for the idea that characteristics acquired during the lifetime of an organism, from either environmental or behavioural effects, may be passed on to the offspring. Charles Darwin first had significant contact with [[Lamarckism]] during his time at the [[University of Edinburgh Medical School]] in the late 1820s, both through [[Robert Edmond Grant]], whom he assisted in research, and in Erasmus's journals.<ref>{{cite book |last1=Browne |first1=E. Janet |title=Charles Darwin: Vol. 1, Voyaging |date=1995 |publisher=Jonathan Cape |location=London |isbn=978-1-84413-314-7 |pages=72–88}}</ref> Darwin's first known writings on the topic of Lamarckian ideas as they related to inheritance are found in a notebook he opened in 1837, also entitled ''Zoonomia''.<ref>{{Cite book |title=The Cambridge companion to Darwin |url=https://archive.org/details/cambridgecompani00hodg_248 |url-access=limited |publisher=Cambridge University Press |others=Hodge, M. J. S. (Michael Jonathan Sessions), 1940-, Radick, Gregory. |year=2003 |isbn=978-0511077692 |location=Cambridge, UK |pages=[https://archive.org/details/cambridgecompani00hodg_248/page/n55 40]–41 |oclc=57383252}}</ref> Historian Jonathan Hodge states that the theory of pangenesis itself first appeared in Darwin's notebooks in 1841.<ref>{{Cite book |title=The Cambridge companion to Darwin |url=https://archive.org/details/cambridgecompani00hodg_248 |url-access=limited |date=2003 |publisher=Cambridge University Press |others=Hodge, M. J. S. (Michael Jonathan Sessions), 1940-, Radick, Gregory. |isbn=978-0511077692 |location=Cambridge, UK |pages=[https://archive.org/details/cambridgecompani00hodg_248/page/n78 63] |oclc=57383252}}</ref>

In 1861, the Irish physician [[Henry Freke]] developed a variant of pangenesis in his book ''Origin of Species by Means of Organic Affinity''.<ref>[[Alexander Macalister|Macalister, Alexander]]. (1870). ''Reviews and Bibliographical Notices''. In ''[[Irish Journal of Medical Science|Dublin Quarterly Journal of Medical Science]], Volume 50''. Fannin and Company. p. 131</ref> Freke proposed that all life was developed from microscopic organic agents which he named ''granules'', which existed as 'distinct species of organizing matter' and would develop into different biological structures.<ref>{{Cite book |url=https://play.google.com/store/books/details?id=a944AAAAMAAJ&rdid=book-a944AAAAMAAJ&rdot=1 |title=On the origin of species by means of organic affinity |last=Freke |first=Henry |date=1861 |publisher=Longman and Co.}}</ref>

Four years before the publication of ''Variation'', in his 1864 book ''Principles of Biology'', [[Herbert Spencer]] proposed a theory of "physiological units" similar to Darwin's gemmules, which likewise were said to be related to specific body parts and responsible for the transmission of characteristics of those body parts to offspring.<ref name="Deichmann 2010"/> He supported the [[Lamarckism|Lamarckian]] idea of transmission of acquired characteristics.

Darwin had debated whether to publish a theory of heredity for an extended period of time due to its highly speculative nature. He decided to include pangenesis in ''Variation'' after sending a 30-page manuscript to his close friend and supporter [[Thomas Huxley]] in May 1865, which was met by significant criticism from Huxley that made Darwin even more hesitant.<ref name="Geison69"/> However, Huxley eventually advised Darwin to publish, writing: "Somebody rummaging among your papers half a century hence will find Pangenesis & say 'See this wonderful anticipation of our modern Theories—and that stupid ass, Huxley, prevented his publishing them'"<ref>{{citation |url=https://www.darwinproject.ac.uk/letter/DCP-LETT-4875.xml |title=Letter 4875 – Huxley, T. H. to Darwin, C. R., 16 July (1865) |publisher= Darwin Correspondence Project }}</ref> Darwin's initial version of pangenesis appeared in the first edition of ''Variation'' in 1868, and was later reworked for the publication of a second edition in 1875.