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Evolution above the Species Level (Rensch, 1960)

Bernhard Rensch

"Mutations causing positive allometric growth [JLJ - allometry: The disproportionate growth of a part or parts of an organism as the organism changes in size, American Heritage Dictionary] of certain tissues will be especially important, as an increase of cell number may mean the first step of differentiation and the formation of new organs... such an increase of a tissue may not serve any special function at first. Later on ... the 'superfluous' tissue may be 'employed' by a new function in the course of subsequent evolution."

JLJ - Rensch puts your High School biology teacher to shame with his detailed knowledge of, well, all things biological. Of particular interest is the concept of evolutionary experimentation in light of the 'natural' selection which formed humans and other animals.

Reflect for a minute - evolution must have produced a mind boggling number of living creatures, each slightly different from parent or parents, and each an individual study in how a machine can evolve a plan, experimentally of course, to 'select' a stance with enough practically useful, transformable and adaptable potential to effectively 'play' a complex game of strategy.

Perhaps, as I believe, if we use evolutionary experimentation to construct a diagnostic test of the adaptive capacity to mobilize coercion, and evolve our diagnostic test only where it needs to be evolved, we can do just that.

p.226-228 Positive allometry, and sometimes negative allometry, as well, causes the development of excessive structures, some of which are referred to as luxuriant or overspecialized structures, because their special function is unknown or does not seem to correspond to the amount of material needed for their construction.

p.275 new organs usually do not arise as something absolutely new but result from differentiations and organ systems that evolved long ago (such as neurons, blood vessels, and inducing agents), and that the evolution of new organs is not directed towards a certain aim.  This is quite obvious from the numerous 'detours' in development, in which certain structures had more or less completely to change their function once or several times (compare Dohrn, 1875; Kleinenberg, 1886).

p.279 Summing up, we may state that the evolution of new structural types and of new organs needs no other explanation than specific and generic differentiation, i.e. the combined effect of mutation and selection.

p.281 the problem of progressive evolution, observed in so many phylogenetic branches, needs a consideration of its own. I have proposed referring to it as anagenesis, whereas the normal branching of lines of descent should be distinguished as kladogenesis.

p.284 Huxley (1954) defined biological progress as an unrestricted type of improvement permitting further improvement. Similarly Simpson (1949) emphasized that 'progress that broadens the chances of further progress' and 'progress in adaptability' are the most important characters of evolutionary progress.

p.289-290 Mutations causing positive allometric growth [JLJ - allometry: The disproportionate growth of a part or parts of an organism as the organism changes in size, American Heritage Dictionary] of certain tissues will be especially important, as an increase of cell number may mean the first step of differentiation and the formation of new organs... such an increase of a tissue may not serve any special function at first. Later on ... the 'superfluous' tissue may be 'employed' by a new function in the course of subsequent evolution.

p.291 Franz (1935) regarded an improved working efficiency as an essential character of evolutionary progress.

p.297 definite evolutionary progress is possible only by a progress that broadens, rather than narrows, the chances of further progress. Simpson (1949) therefore emphasized that 'progress in adaptability' is one of the characteristics of evolutionary progress, and in this context J.S. Huxley (1954) spoke of 'nonrestrictive improvement' permitting further improvement.

p.298 First H. Spencer and later Plate, Sewertzoff, Beurlen, J.S. Huxley, and Simpson regarded an increased independence of and a better control over the environment as typical characters [JLJ - characteristics? or indicators?] of evolutionary progress, enabling the progressive types to extend their ranges of distribution and to produce more diversified forms... As stressed by Plate, there are numerous exceptions to this statement.

p.299 Anagenesis, then, is only one of the possible types of evolution, and it was caused by characters representing selectable advantages of a more general importance.

p.326-327 Whether a certain sensation out of several simultaneous ones is selected, and whether our attention is focused on this special sensation, depends on its intensity, its emotional accent (positive or negative), and its assimilability (i.e., its equality or similarity to sensations experienced previously)... In the process of association, dominant, intense, and positively accented mental images will gain supremacy and repress other less intense or less pleasant ones, so that a sequence of associations proceeding in a certain direction results. 'We cannot think the way we would like to, but our thinking is determined by the kind and constellation of associations at any moment' (Ziehen, 1924, p. 498). [JLJ - I would say that we attend as part of a strategy to maintain a stance or advance a position in the face of both the known and the unknown. We look for cues which suggest certain classifications apply or do not apply, and which suggest certain changes in position are appropriate.]