ABSTRACT
All living things actively respond to the environment in which they exist; indeed, this may be close to a definition of what it means to be alive. We, descendants of the first land-living vertebrates, have a number of specialised senses that have evolved to sustain survival – to make and maintain adaptive contact with the environment. Receptors for sources of energy in the terrestrial environment that have proved beneficial for survival have evolved and become specialised for the needs of each species. Through the action of their senses, living things seek shelter from the elements and other organisms as well as sustenance and sexual partners in order to survive and reproduce. Thus, environmental features that afford protection can be identified and exploited. Sensitivity to the visual, auditory, olfactory, and tactile characteristics of other living things permits identification of foods as well as potential mates or rivals.
