An Evolutionary Psychology
Charles Darwin's experimental research in psychology is surprisingly little known and less understood. One can read the most thorough available histories ( Boakes, 1984; Richards, 1987) and not even find a reference to Darwin's many behavioral experiments or to the theoretical approach that motivated his work (see Reed, 1982c and forthcoming for further historical discussion). This is all the more unfortunate, as Darwin's work still offers important insights.
Darwin treated both behavior and awareness as integral parts of animal life and as subject to the same evolutionary pattern of variation and selection as all other aspects of the living world. He rejected his friend Huxley's theory of animals as automata, and he believed not only that animals had mental states but that these states could be known through a combination of observation, experiment, and ecological analysis. Darwin did not explicitly develop the core ideas of ecological psychology, the concepts of ecological resources for behavior and awareness (what I here term affordances and information), but he came surprisingly close to doing so. Many of the ideas discussed in this chapter are, at the very least, implicit throughout his work on behavior and evolution. Moreover, Darwin invented several basic experimental procedures for analyzing how animals regulate their encounters with their surroundings. It is this Darwin, the experimental behaviorist and evolutionist, who is surprisingly still unknown, more than a century after his death. A convenient overview of his efforts at creating an experimental and evolutionary science of behavior can be found by reviewing his studies of earthworm activities and awareness, as I now proceed to do.
Earthworms spend most of their time burrowing in the ground. Because worms are covered with a layer of sensitive skin, this habitat can be challenging for them. Worms whose skin becomes desiccated through heat or evaporation will die. Worms avoid desiccation through a number of behavioral adaptations that were first studied by Charles Darwin ( 1881; see Reed, 1982c). This case is so interesting in part because earthworms have neither separate sensory organs (although one might well count their entire epi-