Evolutionary Psychology

Volume II

Neil Levy, Stefan Linquist

• Publisher: Routledge
• Year: 2017
• Print ISBN:
  9780754627555
• eBook ISBN:
  9781351937993
• Topic: Biological Sciences
• Subtopic: Evolution
• Index: Biological Sciences

Evolutionary approaches to the study of human beings have been able to explain the origin and maintenance of many of the features of our bodies. Many thinkers believe that an evolutionary approach will be equally fruitful when it comes to explaining the features of our minds. Since our behaviour is driven by our minds, our cognitive dispositions and processes are likely to have been a target of selection and adaptation. This volume collects recent prominent explorations of this theme, as well as the voices of dissenters who argue that our minds are far more significantly the product of culture than of evolution.

Part I
Theoretical Background

[1]

Evolutionary Psychology: A New Paradigm for Psychological Science

David M. Buss

University of Michigan

Psychological science is currently in conceptual disarray, characterized by unconnected mini-theories and isolated empirical findings. We lack a theory of the functional properties of the human mind that could provide the needed integration—a theory about what the mechanisms of mind are “designed" to do. Evolutionary psychology provides the conceptual tools for emerging from this fragmented state. In this target article, I outline the fundamental premises of evolutionary psychology; illustrate the application of evolutionary psychology to domains such as reasoning, social exchange, language, aggression, jealousy, sex, and status; and then consider the implications of evolutionary psychology for the key branches of social, personality, developmental, and cognitive psychology and suggest ways in which these disciplinary boundaries can be transcended. I conclude by looking at the emergence of evolutionary psychology as our field matures into the 21st century.

After more than a century, the social sciences are still adrift, with an enormous mass of half-digested observations, a not inconsiderable body of empirical generalizations, and a contradictory stew of ungrounded, middle-level theories expressed in a babel of incommensurate technical lexicons. (Tooby & Cosmides, 1992, p. 23)

Anyone familiar with the broad field of psychology knows that it is in theoretical disarray. The different branches—such as cognitive, social, personality, and developmental—proceed in relative isolation from one another, at most occasionally borrowing like a cup of sugar a concept here and a method there from a neighbor. Within each branch, psychologists also fail to reach consensus. Mini-theories proliferate unconnected, each conceived to account for a particular set of phenomena, such as obedience to authority, children’s concepts of mind, or the effects of priming on categorization tasks. Although psychologists assume that the human mind is a whole and integrated unity, no metatheory subsumes, integrates, unites, or connects the disparate pieces that psychologists gauge with their differing calipers.

An important new theoretical paradigm called evolutionary psychology is emerging that offers to provide this metatheory. This target article describes the basic features of evolutionary psychology and draws out several key implications for psychological science. It covers recent empirical work conducted using the principles of evolutionary psychology in the areas of jealousy, reasoning abilities, social exchange, decision rules, language, mate preferences, status, aggression, and sex. It considers the consequences for branches of psychology such as social, personality, cognitive, developmental, and cultural. It concludes by looking to the future of evolutionary psychology—its promises, its pitfalls, its illuminations, its limitations.

Fundamental Principles of the New Paradigm

All Psychological Theories Imply Evolved Mechanisms

It does not seem to be generally known among psychologists that all manifest behavior depends on underlying psychological mechanisms—information-proc e s sin g devices, decision rules, and so on—in conjunction with contextual input into those mechanisms. No behavior can be produced without them. If dogs and cats respond to the same stimuli with different responses, it is because the psychological mechanisms of dogs and cats differ. If a child and an adolescent respond differently to the same stimulus, it is because they differ in their psychological mechanisms. If a man and a woman differ in their behavior in response to identical input, it is because they possess somewhat different psychological mechanisms. The reasons that a person obeys authority, conforms to the group, values particular mates, and responds with rage when provoked in particular ways—and a blank slate does not—is because the person possesses a particular set of psychological mechanisms absent in the blank slate.

All psychological theories, even the most ardently environmental ones, imply the existence of psychological mechanisms (Quine, 1981; Symons, 1987). Skinner’s theory of operant learning, for example, implies the existence of domain-general mechanisms that cause organisms to alter their behavioral output in accordance with the history of reinforcement they have experienced. The mechanisms Skinner implies are among the most domain general ever proposed—they are presumed to operate in the same manner across different domains such as feeding and mating and, remarkably, also are presumed to be the same across different species. Festinger’ s (1957) theory of cognitive dissonance, to take another example, implies the existence of internal psychological mechanisms that cause discrepant thoughts or behaviors to feel uncomfortable and that cause people to alter one of those thoughts or behaviors to make the two more consistent. Latané’s (1981) theory of social loafing implies the existence of human psychological mechanisms that cause people to diminish effort at a project as a function of the presence of others.

All psychological theories—be they cognitive, social, developmental, personality, or clinical—imply the existence of internal psychological mechanisms. Unfortunately, the precise nature of these mechanisms is often left implicit. Despite the lack of explicitness, it is clear that no behavior can be produced in the absence of psychological mechanisms. Because all psychological theories imply underlying mechanisms, they also imply a human nature. What are the origins of basic psychological mechanisms that comprise human nature?

Evolution by Natural Selection Is the Only Known Causal Process Capable of Producing Complex Physiological and Psychological Mechanisms

Only a few causal processes have been proposed over the past two centuries to account for the origins of these complex organic mechanisms known as adaptations (Dawkins, 1986; Mayr, 1982). Several of these, such as orthogenesis and lamarkism, have been shown to be false and are no longer considered viable possibilities. Three remaining possibilities have some adherents. The first is evolution by natural selection (Darwin, 1859, 1871; Hamilton, 1964). The second is creationism. The third is seeding theory—the idea that extraterrestrial organisms visited Earth many years ago andplanted the seeds of life. Creationism is largely incapable of being verified or disproved by observation or experiment and is not a scientific theory. Seeding theory, although it cannot be excluded as a possibility, is not an explanation in itself but, rather, pushes the problem back a step to the causal process that created the origins of the seeds and the extraterrestrial beings that planted them. Evolution by natural selection, in contrast, is a powerful and well-articulated theory that has successfully organized and explained thousands of diverse facts in a principled way (Mayr, 1982).

Because all behavior depends on complex psychological mechanisms, and all psychological mechanisms, at some basic level of description, are the result of evolution by selection, then all psychological theories are implicitly evolutionary psychological theories.¹ No psychological theories imply basic psychological mechanisms that were created by some other causal process. As Symons (1987) phrased it, “we’re all Darwinians” in the sense that all (or nearly all) psychologists believe that evolution is responsible for who we are today. If another causal process exists that is capable of producing complex mechanisms, it has not been made generally known to the scientific community.

Levels of Analysis in Evolutionary Psychology

When I give colloquia about my evolution-based research on human mating strategies, I am sometimes asked questions such as “What evidence would falsify ‘the theory’?” or “Doesn’t the existence of people helping total strangers falsify ‘the theory’?” In order to answer these questions, one must first distinguish between at least four levels of analysis (see Figure 1). The first level is general evolutionary theory—evolution by natural selection, as understood in its modem form as inclusive-fitness theory. Now, at this level, even though general evolutionary theory is called a theory, it is widely regarded by biologists as so well established that it is simply assumed to be correct in its general outlines, and then work proceeds from that assumption but does not test the assumption, at least not directly. There have been thousands of tests of the general theory. New species can be created in the laboratory using its principles. Evolution by natural selection is the guiding metatheoiy for the entire field of biology. There are phenomena that could falsify the general theory—if complex life forms were found to be created in time periods too short for natural selection to have operated (e.g., in 7 days) or if adaptations of organisms were found that evolved for the benefit of intrasexual competitors or for the benefit of other species (Darwin, 1859; Mayr, 1982; Williams, 1966). But no such phenomena have ever been observed or documented.

Figure 1. Simplified depiction of a hierarchy of levels of analysis in evolutionary psychology. Each middle-level theory must be consistent with general evolutionary theory and is subsumed by general evolutionary theory but cannot be logically deduced from general evolutionary theory. A variety of specific evolutionary hypotheses can be derived from each middle-level theory, just as a variety of specific empirical predictions can be generated from each evolutionary hypothesis. Standards of “normal paradigm science” hold for testing each level in the hierarchy.

So, when an evolutionary psychologist tests an evolutionary proposition, she or he is not testing “general evolutionary theory,” just as, when an astronomer tests a particular hypothesis (e.g., about the amount of critical mass in the universe), she or he is not testing “general relativity theory” with each experiment. That theory is assumed to be true, just as evolution by natural selection is assumed to be true for the present purposes. Because no compelling alternatives have been proposed over the past 130 years, and because there is overwhelming evidence supporting general evolutionary theory, these assumptions are reasonable.

Moving one level down, we find middle-level evolutionary theories, such as the theory of reciprocal altruism (Trivers, 1971), the theory of parental investment and sexual selection (Trivers, 1972), and the theory of parasite-host coevolution (Hamilton & Zuk, 1982). These middle-level theories are still fairly broad in that they are theories about entire domains of functioning— for example, the conditions under which parents and their offspring will conflict with one another. These theories are fair game for testing and possible falsification. I’ll examine just one to illustrate this point— Trivers’s theory of parental investment and sexual selection (see Figure 1).

This theory, which is itself an elaboration of Darwin’s (1871) theory of sexual selection, provided one of the key theoretical ingredients for predicting the operation of mate choice and the operation of intrasexual competition. Leaving aside the logical and reproductive underpinnings of Trivers’s theory (which would require a major treatise to spell out), he essentially argued that the sex that invests more in offspring (often, but not always, the female) will evolve to be more choosy about mating, whereas the sex that invests less in offspring will evolve to be more competitive with members of their own sex for sexual access to the valuable high-investing opposite sex. Women, whose minimum parental investment includes a 9-month gestation period, for example, are predicted to have evolved mechanisms that lead to greater choosiness than men, whose minimum parental investment is the contribution of his sperm. The asymmetries between the sexes, in fitness currencies, of the costs of making a poor mate-choice and the benefits of making a wise mate-choice would have created selection pressure for sex-differentiated psychological mate preferences. Trivers and others have developed additional hypotheses about the precise content of mate choice—variousforms of resources, for example, when certain contextual conditions were met such as resource defensibility, variance in resource holdings among potential mates, or whether a long-term or short-term mate is being pursued (Buss & Schmitt, 1993). Some of the specific hypotheses derived from Trivers’s theory are shown in Figure 1. And specific predictions can be derived from each of these hypotheses—predictions about evolved psychological mechanisms or behavioral strategies in a particular species.

In testing these predictions, all the conditions of “normal paradigm science” hold. If the predictions do not pan out empirically, then the hypothesis on which they were based is called into question. If key hypotheses are called into question by several predictive failures, then the truth or value (depending on one’s philosophy of science) of the middle-level theory that generated the hypotheses is doubted. Theories that are consistently supported—as, for example, Trivers’s theory of parental investment and sexual selection has been in hundreds of empirical studies—are hailed as major middle-level theories, especially if they prove highly generative of interesting and fruitful avenues of research. Theories that are not generat...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Acknowledgements
• Series Preface
• Introduction
• Part I Theoretical Background
• Part II The Massive Modularity Hypothesis
• Part III Adaptationism
• Part IV The Environment of Evolutionary Adaptedness
• Part V Cultural Universals
• Index