1 - The Evolution of Human Communication Systems

Abstract

This chapter discusses some of the basic elements of modern evolutionary theory as it applies within biology. This theory seeks to account for changes that take place within populations of plants and animals over time. The individuals making up such populations at a given moment display wide variability in both phenotype as well as genotype. There are two main forces in evolution: variation created by random factors and a filter, whose properties are determined by factors that may be subsumed under the rubric of natural selection, which maintains or alters distributions of characteristics in various ways. One of the outcomes of the gradual accrual of divergent characteristics is the radiation of species, that is, the development of populations that do not interbreed. Such populations may be separated in time or may be coextant. The barriers to interbreeding involve a number of factors termed as isolating mechanisms. The biochemical evidence derives from three basic types of comparisons. One involves combining single strands from the DNA of two species. Such strands will recombine except at those points at which they are chemically different. A second method involves comparing the sequencing of amino acids in various types of protein molecules, such as those found in the blood. Finally, the immunological approach involves injecting a protein, such as serum–albumin, taken from one species into an animal from another species. This will result in antibodies being produced.