ABSTRACT
Evolution in the broad sweep of phylogeny can be comprehended with absolutely no knowledge of the genetic processes by which evolution occurs. Central to genetic considerations is the realization that evolution is a phenomenon of populations rather than individuals. Organic evolution is a population phenomenon consisting of changes in the frequencies of genes that constitute the gene pools of local populations. Functional studies of intraspecific nervous system variations that are grounded in genetics have barely begun but include J. P. Hegmann’s work with speed of neural conduction and investigations related to the topography of visual pathways within a number of different mammalian species. The source of continuity and of change across evolutionary time is samplings of genes. For each generation the genes of a sexually reproducing local population are reshuffled into new and usually unique genotypes.
