3 Common Myths About Evolutionary Psychology

The following is an interesting conversation between Richard Dawkins and David M. Buss.


The following extract is taken from David M. Buss' book Evolutionary Psychology: The New Science of the Mind.

Misconception 1. Human Behaviour Is Genetically Determined

Genetic determinism is the doctrine that argues that behavior is controlled exclusively by genes, with little or no role for environmental influence.

Much of the resistance to applying evolutionary theory to the understanding of human behavior stems from the misconception that evolutionary theory implies genetic determinism. Contrary to this misunderstanding, evolutionary theory represents a truly interactionist framework.

Human behavior cannot occur without two ingredients: (1) evolved adaptations and (2) environmental input that triggers the development and activation of these adaptations.

Consider calluses as an illustration. Calluses cannot occur without an evolved callus-producing adaptation, combined with the environmental influence of repeated friction to the skin. Therefore to invoke evolutionary theory as an explanation for calluses, we would never say “calluses are genetically determined and occur regardless of  input from the environment.” Instead, calluses are the result of a specific form of interaction between an environmental input (repeated friction to the skin) and an adaptation that is sensitive to repeated friction and contains instructions to grow extra new skin cells when the skin experiences repeated friction.

Indeed, the reason that adaptations evolve is that they afford organisms tools to grapple with the problems posed by the environment. So notions of genetic determinism—behaviors caused by genes without input or influence from the environment—are simply false. They are in no way implied by the evolutionary theory or by evolutionary psychology.

Misconception 2: If It’s Evolutionary, We Cannot Change It

A second misunderstanding is that evolutionary theory implies that human behavior is impervious to change.

Consider the simple example of calluses again. Humans can and do create physical environments that are relatively free of friction. These friction-free environments mean that we have designed change—a change that prevents the activation of the underlying callus-producing mechanisms. Knowledge of these mechanisms and the environmental input that triggers their activation give us the power to decrease callus production.

In a similar manner, knowledge of our evolved social psychological adaptations along with the social inputs that activate them gives us power to alter social behavior, if that is the desired goal.

Consider the following example. There is evidence that men have lower thresholds than women for inferring sexual intent. When a woman smiles at a man, male observers are more likely than female observers to infer that the woman is sexually interested. This sexual over-perception bias is most likely part of an evolved psychological adaptation in men that motivates them to seek casual sexual opportunities.

Knowledge of this mechanism, however, allows for the possibility of change. Men, for example, can be educated with the information that they have lower thresholds for inferring sexual intent when a woman smiles at them. This knowledge can then be used by men, in principle, to reduce the number of times they act on their faulty inferences of sexual interest and decrease the number of unwanted sexual advances they make toward women.

Knowledge about our evolved psychological adaptations along with the social inputs that they were designed to be responsive to, far from dooming us to an unchangeable fate, can have the liberating effect of paving the way for changing behavior in areas in which change is desired. This does not mean that changing behavior is simple or easy. More knowledge about our evolved psychology, however, gives us more power to change.

Misconception 3: Current Mechanisms Are Optimally Designed

The concept of adaptation, the notion that mechanisms have evolved functions, has led to many outstanding discoveries over the past century. This does not mean, however, that the current collection of adaptive mechanisms that make up humans is in any way “optimally designed.”

An engineer might cringe at some of the ways that our mechanisms are structured, which sometimes appear to be assembled with a piece here and a bit there. In fact, many factors cause the existing design of our adaptations to be far from optimal.

Let’s consider two of them. One constraint on optimal design is evolutionary time lags. Recall that evolution refers to change over time. Each change in the environment brings new selection pressures. Because evolutionary change occurs slowly, requiring hundreds or thousands of generations of recurrent selection pressure, existing humans are necessarily designed for the previous environments of which they are a product. Stated differently, we carry around a Stone Age brain in a modern environment. In other words, “we are walking archives of ancestral wisdom” (Cronin, 1991).

A strong taste preference for fat and sugar, adaptive in a past environment of scarce food resources, now leads to clogged arteries, Type 2 diabetes, and heart attacks. The lag in time between the environment that fashioned our mechanisms (the hunter-gatherer past that formed much of our selective environment) and today’s environment means that our some of our existing evolved mechanisms may not be optimally designed for the current environment.

A second constraint on optimal design pertains to the costs of adaptations. Consider as an analogy the risk of being killed while driving a car. In principle, we could reduce this risk to near zero if we imposed a five-mile-per-hour speed limit and forced everyone to drive in armored trucks with ten feet of padding on the inside. But we consider the costs of this solution to be ridiculously high.

Similarly, we might consider a hypothetical example in which natural selection built into humans such a severe terror of snakes and spiders that people never ventured outdoors. Such a fear would surely reduce the incidence of snake and spider bites, but it would carry a prohibitively high cost. Further, it would prevent people from solving other adaptive problems, such as gathering fruits, plants, and other food resources necessary for survival. In short, the existing fears of snakes and spiders that characterize humans are not optimally designed—after all, thousands of people do get bitten by snakes every year, and some die as a result. But it works reasonably well, on average.

All adaptations carry costs. Selection favors a mechanism when its benefits outweigh the costs relative to other designs existent at the time. Humans have evolved mechanisms that are reasonably good at solving adaptive problems efficiently, but they are not designed as optimally as they might be if costs were not a constraint. Evolutionary time lags and the costs of adaptations are just two of the many reasons why adaptations are not optimally designed.