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Contemporary Perspectives on the Meaning, Roles, and Implications of Chance in Evolution

Grant Ramsey, Charles H. Pence, eds. (2016) Chance in Evolution. The University of Chicago Press, Chicago & London. ISBN: 978-0-226-40188-1, 359 pages, price: USD 45 (paperback)

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  1. Preformationism was the view that either the sperm or the ova contain a fully differentiated individual, which merely grows during embryonic development.

  2. Statisticalism is the thesis that evolutionary factors such as selection, drift, and mutation should not be seen as causes of evolutionary changes. It was defended in a series of papers by Walsh, Lewens, Ariew, and Matthen. According to the statisticalists, parameters representing selection, drift, etc. offer only statistical information about some (actual or expected) values, but these statistical values do not represent causes. Causalism, contrarily, is the thesis that the evolutionary factors should be viewed as causes.

  3. According to which chance events have determinate causes, but those causes are unknown to us, so we must treat their outcomes probabilistically.

  4. Speciation always requires the reproductive isolation of the variants that will become separate species. In the sympatric model, reproductive isolation occurs without geographical isolation. In the allopatric model, what causes reproductive isolation is, precisely, the presence of some geographical barrier.

  5. Other authors (e.g., Desmond and Moore, Darwin’s Sacred Cause) have connected his theory of common origin with his anti-slavery views. Ruse also cites passages (pp. 129–130) in which Darwin speaks of the progress of civilizations (of “civilized” and “lower” races).

  6. However, Ruse does show that, in other places, Darwin does seem to look for such absolute criteria under which humans would be most improved (such as the amount of differentiation and specialization of the parts).

  7. Ruse attributes the view that all ecological niches will tend to become occupied, and thus that high intelligence was inevitable somewhere, to both Gould and Conway Morris. He does not (explicitly at least) attribute them the view that some organisms are better/more perfect than others for occupying better niches (no one is cited when this is said). Gould, in fact, is characterized as an anti-progress thinker.

  8. McShea and Brandon, and (again) Gould, are put forth as examples of authors who have argued for a (non-selective) trend towards an increase of complexity. However, Ruse is careful not to attribute them the view that this counts as progress in any sense. It does count as such for the other author cited as holding this view, Herbert Spencer.

  9. Very often (and Merlin does this), the example of drawing balls from an urn is used to illustrate this. Suppose there are 50 red and 50 black balls in an urn. If every particular ball has the same probability of being sampled, the sampling process is called indiscriminate. If, on the other hand, red balls are more slippery and black balls are stickier (so that each black ball has a greater probability of being sampled than each red ball) the process is discriminate. Additionally, if after sampling a ball from the urn it is returned to it, then the process is called “with replacement.” If they are not, it is without replacement. In processes without replacement, the probabilities of some events may change over time. For instance, suppose one indiscriminately samples a ball and gets a red one. Then the probability of getting a red one at the second turn will be P(Red) = 49/99. If one gets another red ball, then in the third turn P(red) = 48/98 and P(black) = 50/98, despite each particular ball still having the same probability of being sampled.

  10. Assuming, of course that the transformation c1 → c2 and c2 → c1 both have the same cost (are equally likely to happen). If one drops this (standard) assumption, (b) might be preferred to (a) despite involving a greater number of transformations.

  11. In cladistic taxonomy, the criterion to group species together is not morphological similarity but rather ancestry: species A and B belong to a category that C does not only if they share a common ancestor that is not an ancestor of C. In other words, only monophyletic groups (groups that include an ancestor and only and all its descendants) should get their own taxonomic categories (not all monophyletic groups will get a name, though).

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Correspondence to Ariel Jonathan Roffé.

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Roffé, A.J. Contemporary Perspectives on the Meaning, Roles, and Implications of Chance in Evolution. Sci & Educ 27, 1003–1016 (2018).

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