Darwin (1859) stated that the origin of taxa was natural selection acting upon variants within a population to yield differential reproduction of the most adapted (Mayr, 1982). As briefly described in the preceding chapter, the theoretical principle I shall elaborate here is that the origin of categories in higher brain function is somatic selection among huge numbers of variants of neural circuits contained in networks created epigenetically in each individual during its development; this selection results in differential amplification of populations of synapses in the selected variants. In other words, I shall take the view that the brain is a selective system more akin in its workings to evolution than to computation or information processing. The elaboration of this view will be an exercise in population thinking (Mayr, 1982), which considers that variance in a population is real and that individuality provides the basis for selection. This exercise in neural Darwinism (Edelman, 1985a) must nevertheless be grounded in quite specific mechanisms that requie explicit description in terms of our knowledge of the nervous system. (Edelman, 1987, p. 25)
[HOME] [NEXT]Just as Darwin's view eliminated the need for creation by design, showing how taxa can be evolved (bottom-up) from populations through natural selection, so this selectionist view of the brain eliminates the need to create perceptual categories from the top down. Synaptic changes in linked neural maps leading to such categories are perhaps the most exquisite result of epigenetic processes creating form from place Topobiology at a minute scale reaches its highest point of evolutionary sophistication in complex brains containing many such maps, and its principles provide a central basis for the workings of such brains. (Edelman, 1988, p. 207)