Behaviorists, aspiring to be seen as rigorous scientists, followed in the footsteps of physicists. They considered the person as a mechanism. In presenting humanism as an antithesis to this behavioristic thesis and interactionism as a synthesis, we have gone beyond a passive model to an active and then an interactive model, beyond dealing with only input information to dealing with stored information and then fedback information. We have presented in chapters 2, 3, and 4 progressively more and more sophisticated models of the person. However, they are still mechanistic models. The person is still considered as an information-processing system. Note that Miller, Galanter, and Pribram sought inspiration in the analogy with the computer.

The next two chapters focus on human development - from animal to human - phylogenetic development (Chapter 5) and from child to adult - ontogenetic development (Chapter 6). They shift our focus from physics to biology. Darwin's theory of phylogenetic development and Piaget's theory of ontogenetic development place the person firmly where s/he belongs within the field of biology rather than physics, as an organism rather than a mechanism.

This chapter of our story opens in a quiet country home in an English village. Our next major character is seen puttering about in his greenhouse and muttering about in his study. It was in this place and in this manner - apart from a famous voyage around the world aboard the H.M.S. Beagle - that Charles Darwin spent most of his life. Yet this uneventful life of this unassuming man in this unspectacular setting had a greater impact on our world than did the lives of some of the more flamboyant figures - the Caesars, the Napoleons, the Hitlers - who have stomped around our globe.

Darwin created a revolution. Not that shoddy shift in political personnel that typically passes for a revolution, but a real revolution - a change in our view of ourselves. After carefully collecting and collating evidence for 17 years, Darwin gently but firmly told us that we are not a special creation of God with an exclusive soul but an animal on the same scale as our dogs and our cows. After the inevitable violent reaction - Scopes v. State of Tennessee, Professor Huxley v. Bishop Wilberforce - we swallowed this bitter pill. Indeed, we now find it not only palatable but sweet. Most of us feel better as raised apes than as fallen angels.

Psychologists are often criticized for spending so much time working with animals. They tend to defend themselves in terms of practical advantages. You need not make appointments with animals, or establish rapport with them, or pay them for their services. You can cage animals, shock them, and interbreed them. Animals have simpler nervous systems than humans and can, therefore, be better studied by our as-yet-simple tools. Animals take less time to mature than humans and, thus it is easier to study the effect of early experience on late behavior. Experimenters tend to prefer subjects who are unlikely to outlive them.

Darwin provides a better answer. I study the behavior of rats because I am interested in the behavior of humans. Since rat and man both developed according to the same principles, as expounded in the theory of evolution, some insight into man can be gained by the study of the rat. Just as we get some insight into a single organism by tracing the development of that organism (ontogenetic approach), we can get some insight into a species by tracing the development of that species (phylogenetic approach).

Alfred Russel Wallace (1823-1913) had discovered the principle of natural selection at the same time as Darwin. Indeed, he published the same theory in the same issue of the same journal [DESMOND & MOORE, Pages 466-471]. Most people assumed, as did I, that he does not get as much credit as Darwin, because he did not spend 17 years accumulating empirical evidence for the theory. However, it is now clear that he had done his homework. The main reason he does not get as much credit is because he subsequently abandoned the theory. He could see no way in which adaptation to a hunter-gatherer society could explain the sophisticated modern mind. How could a species, which evolved by adapting to a hunter-gatherer society, deal with the dramatic shifts to an agricultural society, then to an industrial society, and now to an information society?

We are all familiar with the basic principles of the theory of evolution. Here, however, is a Rip Van Winkle special by way of reminder. There are individual differences from individual to individual within any species. Because of certain environmental conditions, the individuals at one end of a particular scale have some advantage over the others. Because of this advantage, they are more likely to survive. Because they are more likely to survive, they are more likely to reproduce. Because traits are inherited, the next generation of this species will be, on the average, further along toward the desirable end of this scale. This generation, in turn, breeds another generation even further along, and so on and so on.

Let's take a concrete example. Giraffes differ in the length of their necks. The longer-necked giraffes are better able to feed off the leaves in high trees and are thus more likely to survive and reproduce. Since long-necked giraffes tend to have long-necked babies, the next generation will have, on the average, longer necks, and the next generation even longer necks, and so on. Note that no giraffe grows a longer neck during its lifetime by stretching it to reach leaves and then passes its longer neck on to its progeny. This is Lamarck's erroneous concept of the inheritance of acquired characteristics.

Whereas most of us are familiar with the initial reaction to the theory of evolution, we may not be as familiar with its subsequent history. It suffered a decline, because many malicious or simply silly people misused the theory as a rationalization for an extreme interpretation of capitalism as a survival-of-the-fittest principle applied to the social sphere and as an argument for eugenics - the "improvement" of the species by pruning out the unfit [DEGLER].^₁ Social scientists were so horrified by this interpretation of the theory of evolution that they swung to the other extreme of denying any influence of our evolutionary past on our present behavior. Their Standard Social Science Model (SSSM), which underlies the social sciences, including communication studies, assumes that the mind is a "tabula rasa", a blank slate on which culture writes.

The debunking of those false arguments has resulted in a revival of the principle of natural selection as a basic principle for the psychological and social sciences. A spate of recent books by evolutionary psychologists [e. g. BARKOW ET AL, PINKER 2002, WILSON 1998] argue that the human mind, which has evolved over thousands of years to enable us to survive in the harsh arena of our environment, is a medium which determines how the message of culture is received and interpreted. This "tabula" is far from "rasa". Much has been written on this slate over evolutionary times. We cannot deny human nature. They argue therefore that we need to ground our sociology in psychology and our psychology in turn in biology. This inevitably leads to natural selection and the "natural selection" of Charles Darwin, superficially an unlikely candidate, as an important contributor to the psychology of communication.

We tend to think of the theory of evolution as a biological rather than a psychological theory - as concerned with the development of structure rather than of function. Perhaps the emphasis has been on structure because, with the death of an organism, structure survives but function fades. Much evidence for evolution is therefore based on structure (skeletons) or the imprint of structure (fossils). However, the giraffe survives not only because it has a long neck but also because it can use it. The structure-function relationship is a chicken-and-egg problem. We do not know whether an egg is one chicken's way of producing another chicken or whether, as Samuel Butler suggested, a chicken is one egg's way of producing another egg. We do not know whether birds have wings because they fly or fly because they have wings. Modern evolutionary psychology is exploring the evolution of function as well as structure, of the mind as well as of the body. Let us look in turn at the work of three evolutionary psychologists - Paul Ekman, Robin Dunbar, and Steven Pinker - who have continued the work of Darwin by exploring the psychology of communication.