This paper is an attempt to arrive at a species-specific characterization of human consciousness by considering its value as a biological adaptation. The analysis considers conscious phenomena in animals to motivate the distinction between self-consciousness and consciousness; the distinction is substantiated with neurological data. The relation between self-consciousness and language is considered in the light of the evolution of human language. Finally, a mechanism is postulated, based on current neurobiological knowledge, which makes it possible to account for self-consciousness as an epiphenomenon of language.

This paper discusses, first, the selective pressures which led to the two basic types of animal eyes, compound vs. camera eyes. Secondly, it considers what is the significance of the apparent similarity of the wiring patterns in the vertebrate retina and in the optic lobe of the compound eye. No discussion of these matters can be found in the literature since 1915. The present treatment, while it is admittedly only suggestive, is nevertheless open to experimental verification.

Using the results of an optical analysis, a digital computer technique was developed to analyze the relative excitation produced by arbitrary figures at the rhabdom of the receptors of a compound eye. This technique was applied to several sets of figures for the honeybee (Apis mellifera) and a reasonable agreement was found with behavioral data. Similarly, the significance of a fixed cutoff angle for a visual field was investigated. It is concluded that overlap between neighboring ommatidia is highly significant for visual processing in the apposition eye, contrary to the assumptions of the mosaic theory.