on The Origin Of Species

• https://eurekalert.org/pub_releases/2020-03/sjcu-ood031620.php
• https://phys.org/news/2020-03-darwin-evolution-theories-cambridge.html

X1\ (talk) 07:20, 18 March 2020 (UTC)

Just add this one as well https://royalsocietypublishing.org/doi/10.1098/rspb.2019.2702 2A00:1FA0:8CF:BC1C:E032:5418:CC1B:AE5D (talk) 13:34, 20 March 2020 (UTC)

  A discussion is taking place to address the redirect Origin of the species. The discussion will occur at Wikipedia:Redirects for discussion/Log/2020 August 28#Origin of the species until a consensus is reached, and readers of this page are welcome to contribute to the discussion. Soumya-8974 ^talk _contribs ^subpages 10:07, 28 August 2020 (UTC)

  A discussion is taking place to address the redirect TOoS. The discussion will occur at Wikipedia:Redirects for discussion/Log/2020 August 28#TOoS until a consensus is reached, and readers of this page are welcome to contribute to the discussion. Soumya-8974 ^talk _contribs ^subpages 10:09, 28 August 2020 (UTC)

I think it would be useful to point out in the article that The Origin did not explain stabilizing selection and continued to exclude it from the book even after Darwin read Matthew's description of it in 1860.

Darwin's confusion on this point can be seen in the first two sentences of The Origin:

WHEN we look to the individuals of the same variety or sub-variety of our older cultivated plants and animals, one of the first points which strikes us, is, that they generally differ much more from each other, than do the individuals of any one species or variety in a state of nature. When we reflect on the vast diversity of the plants and animals which have been cultivated, and which have varied during all ages under the most different climates and treatment, I think we are driven to conclude that this greater variability is simply due to our domestic productions having been raised under conditions of life not so uniform as, and somewhat different from, those to which the parent-species have been exposed under nature.

It can be seen here that Darwin attributes the greater variation amongst individuals of domestic varieties compared to their progenitor populations in nature as being due to their "conditions of life (environment) [being] not so uniform as, and somewhat different from those [... of] the parent species".

Patrick Matthew in Naval Timber and Arboriculture had seen the role of stabilizing selection in making domesticated populations less varied than their counterparts in nature:

Man’s interference, by preventing this natural process of selection among plants, independent of the wider range of circumstances to which he introduces them, has increased the difference in varieties.

It is clear from this that Matthew sees that preventing natural selection can increase variation. The corollary is that natural selection can decrease variation and does so in nature. This is stabilizing selection. The fact that Matthew was describing stabilizing selection is illustrated by this passage from the advert for his book in the Encyclopedia Britannica:

In embracing the philosophy of plants, the interesting subject of species and variety is considered,– the principle of the natural location of vegetables is distinctly shown,– the principle also which in the untouched wild “keeps unsteady nature to her law,” inducing conformity in species, and preventing deterioration of breed, is explained,– and the causes of the variation and deterioration of cultivated forest trees is pointed out.

The phrase "keeps unsteady nature to her law" is from Milton's Arcades. Whether or not Milton was referring to stasis or conformity within species is not clear to me but it is clear that Matthew was providing an explanation for that phenomenon in his book. In the first passage from Matthew above he inserts the clause "independent of the wider range of circumstances to which [man] introduces them". This shows Matthew recognized that in addition to "preventing [the] natural process of selection" domestication may also expose individuals to a wider range of circumstances. He is making it clear that it is the prevention of natural selection not the wider range of circumstances, as the Origin's first sentences argue, which is responsible for the phenomenon of increased variation in domesticated varieties.

In the third edition of The Origin Darwin includes a historical sketch in which he states that in 1831 Matthew published "precisely the same view on the origin of species as that" propounded in The Origin. Given that Darwin had by now definitely read Matthew's Naval Timber and Arboriculture it is not clear why he does not modify The Origin to remove his erroneous explanation of increased variation on domestication and replace it with Matthew's very much more satisfying explanation. Either he (and also his network of colleagues) still failed to appreciate the argument even after reading it or they had no wish to change The Origin to conform to Matthew's earlier work on a central aspect relating to the operation of natural selection as this would detract considerably from Darwin's status.

Darwin did not describe the stabilizing role of natural selection in The Origin and this should be made clear in the article about The Origin because stabilizing selection is an important component of the dynamics of natural selection. It is interesting to me that among the many instances in the Origin where Darwin favours use and disuse over, or as well as, natural selection there is a high proportion of cases of disuse as opposed to use. Reduction of eyes in animals living in darkness and loss of wings in insects and birds where they are no longer needed are frequently mentioned as cases where disuse instead of or as well as natural selection is suggested. Perhaps this is because the loss of a character is more likely to be brought about by the loss of stabilizing selection than by the action of directional selection. As Darwin did not understand stabilizing selection it is not a surprise that he seeks an explanation not involving natural selection at all or sees a diminished role for it. Of course directional selection can be evoked to explain loss of useless characters (the character may take energy to make and maintain or it may get in the way) but it is less central than stabilizing selection to the explanation.

I think this is a substantial deficit in The Origin's value as a description of natural selection and it would make sense to briefly mention it at the top of the article and then discuss it more fully say in the description of Chapter 1 in the section "Variation under domestication and under nature".

I would be interested in views on this. Gourdiehill (talk) 18:02, 25 March 2024 (UTC)