The Evolution of Intelligence

Robert J. Sternberg, James C. Kaufman, Robert J. Sternberg, James C. Kaufman

• Publisher: Psychology Press
• Year: 2013
• ISBN:
  9781135668440
• Edition: 1
• Topic: Psicología
• Subtopic: Historia y teoría en psicología

How is one to understand the nature of intelligence? One approach is through psychometric testing, but such an approach often puts the "cart before the horse"--the test before the theory. Another approach is to use evolutionary theory. This criterion has been suggested by a number of individuals in the past, from Charles Darwin in the more distant past to Howard Gardner, Stephen Gould, Steven Pinker, Carl Sagan, David Stenhouse, and many others. The chapters in this book address three major questions:
1. Does evolutionary theory help us understand the nature of human intelligence?
2. If so, what does it tell us about the nature of human intelligence?
3. And if so, how has intelligence evolved? The goal of this book is to present diverse points of view on the evolution of intelligence as offered by leading experts in the field. In particular, it may be possible to better understand the nature and societal implications of intelligence by understanding how and why it has evolved as it has. This book is unique in offering a diversity of points of view on the topic of the evolution of human intelligence.

1

The Search for Criteria: Why Study the Evolution of Intelligence?

Robert J. Sternberg
Yale University

Perhaps the most difficult challenge in the study of intelligence is figuring out the criteria for labeling a thought process or a behavior “intelligent.” How does one decide?

A number of different approaches have been tried to figure out what criteria one can use to decide what constitutes “intelligence.” The thesis of this chapter is that evolutionary arguments constitute one of three such criteria that can be readily incorporated, given a conventional definition of intelligence in terms of adaptation to the environment.

DEFINITIONS OF INTELLIGENCE

Conceptual Definitions

Conceptual definitions are opinions of experts or laypersons about what constitutes intelligence, or intelligent thought and behavior. Two major symposia have directly addressed this issue.

One symposium (“Intelligence and its Measurement,” 1921) involved 14 experts giving their views on the nature of intelligence. This symposium produced definitions such as “having learned or ability to learn to adjust oneself to the environment” (Colvin, 1921), “ability to adapt oneself adequately to relatively new situations in life” (Pintner, 1921), and “the capacity to inhibit an instinctive adjustment” (Thurstone, 1921). Note that a major theme in these definitions was the role of adaptation to the environment.

The second symposium (Sternberg & Detterman, 1986) involved opinions of 24 experts in the field of intelligence and produced answers that overlapped with those in the earlier symposium. There was perhaps greater emphasis in these later definitions on metacognition. But the main theme once again was adaptation to the environment.

Definitions also may be extracted from experts or from laypersons by studying these individuals’ implicit theories of intelligence. This route was followed in two separate investigations (Sternberg, 1985; Sternberg, Conway, Ketron, & Bernstein, 1981) and produced a variety of responses, depending in part on whether the individuals were professionals or laypersons, and, if professionals, on their field of study. For example, laypersons suggested practical problem-solving ability, verbal ability, and social-competence abilities, whereas experts placed more emphasis on academic skills. However, the skills they emphasized depended on the skills they needed to succeed in their own fields. Implicit-theory studies also have been done cross-culturally, with extremely diverse results (see review in Sternberg & Kaufman, 1998).

Operational Definition

Definitions can also be sought that skirt the issue altogether. For example, Boring (1923) achieved what little fame he has in the field of intelligence for his famous remark that intelligence can and should be defined operationally as that which the intelligence tests test. The circularity of this definition—the tests are designed to measure intelligence, which then is defined in terms of whatever they measure—has made the definition unappealing to many theorists in the field.

THEORIES OF INTELLIGENCE

A second approach is to propose a theory of intelligence, from which some kind of definition is supposed to follow somehow. These theories can be classified in a number of different ways. One scheme is in terms of the metaphor of mind they presuppose. These metaphors characterize the grounds through which intelligence needs to be understood.

Sternberg (1990) suggested that many theories can be viewed as falling under one of seven metaphors. What are these seven metaphors?

First, the geographic metaphor is based on the notion that a theory of intelligence should provide a map of the mind (see Brody, 2000; Carroll, 1993; Horn, 1994; Spearman, 1927; Thurstone, 1938;). Intelligence then comes to be defined in terms of underlying factors of the mind, which Vernon (1971) likened to lines of longitude and latitude for understanding how the mind works.

Second, the computational metaphor envisions the mind as a computing device and analogizes the processes of the mind to the operations (software) of a computer (see Deary, 2000; Hunt, 1980; Lohman, 2000; Sternberg, 1983). The operations of the mind are then characterized in terms of processes, strategies, and mental representations used in processing information.

Third, the biological metaphor (which includes evolutionary notions) seeks to understand intelligence in terms of the workings of the brain (Ertl & Schafer, 1969; Haier et al., 1988; Haier, Siegel, Tang, Abel, & Buchsbaum, 1992; see Jerison, 2000; Vernon, Wickett, Bazana, & Stelmack, 2000). Biological theorists often attempt to map cognitive activity onto various portions of the brain, or to show that certain kinds of responses emitted by the brain (e.g., evoked potentials) relate to psychometrically measured intellectual performance. Or they may try to understand the evolutionary origins of intelligence.

Fourth, the epistemological metaphor, due primarily to Jean Piaget (e.g., Piaget, 1972), seeks to understand intelligence as an equilibration between assimilation and accommodation. Individuals assimilate new objects into existing mental schemas, or change existing schemas to accommodate objects that do not well fit into old schemas.

Fifth, the anthropological metaphor views intelligence as a cultural invention (e.g., Berry, 1974; Greenfield, 1997). On this view, the mental processes underlying intelligence may or may not change as a function of culture, but the behaviors considered to be intelligent certainly do. What is considered intelligent behavior in one culture may be considered to be unintelligent in another (Serpell, 2000).

Sixth, the sociological metaphor considers how socialization affects intellectual development (e.g., Feuerstein, 1980; Vygotksy, 1978). One might examine, for example, how children internalize experiences they first encounter in an interpersonal context (see Chen & Siegler, 2000).

Seventh, the systems metaphor tries to understand the various aspects of intelligence and how they work together as a system (e.g., Gardner, 1983, 1999; Sternberg, 1985, 1997, 1999). According to this metaphor, the various approaches to intelligence need to be systemically integrated.

The different metaphors vary in a tremendous number of respects. But interestingly, they have one thing in common with the diverse definitions. It typically is assumed that the core concept underlying intelligence is adaptation to the environment, broadly conceived.

THREE ADAPTATIONIST CRITERIA

If intelligence is to be understood as adapation to the environment, broadly conceived, then how might we go about discovering the mental processes and behaviors that can be labeled as intelligent? Three criteria suggest themselves. These criteria differ from largely arbitrary listings of criteria (e.g., Gardner, 1983) in that they all derive from the virtually universally accepted notion of intelligence as adaptation to the environment.

Criterion 1: Correlations with Success

Success is often defined in terms of cultural adaptation. When it is so defined, it makes sense to correlate performance on measures of intelligence with multiple measures of success; however, they may be culturally defined. These measures will differ from one culture to another. But the variation in what constitutes success is not limited to cultural adaptation. Adaptive success also varies with biological niche. Success for a bird is certainly different from success for a human. And even humans need different skills to succeed in different environments, such as in cold mountainous regions versus hot tropical rain forests.

Criterion 2: Mental Skill Development

All organisms are designed to become increasingly independent and better able to adapt to the environment with increasing age, up to a certain point. Then, in the later portion of their lives, their adaptive skills may decrease with age. Binet and Simon (1905/1916) were among the first to recognize that a scale for measuring intelligence could be constructed on the basis of items on which performance differed as a function of age. The whole notion of mental age, although no longer in general use, derived from the view that mental growth during childhood was such as to render an individual more adaptive to the environment. Increases in age can result in increases both in cultural adaptation, considered in the first criterion, and biological adaptation, considered in the third criterion.

Criterion 3: Evolutionary Origins and Development

If we start with biological adaptation as the core of intelligence, then a primary means for understanding what intelligence is would have to be in terms of the evolutionary antecedents of thought and behavior. This approach has not been widely used, although its origins are not particularly recent (Darwin, 1859, 1872/1965; see also Stenhouse, 1973).

This volume is an attempt to remedy the relative dearth of literature on the evolution of intelligence in comparison with, for example, the psychometric correlates of intelligence or the development of intelligence. From an adaptationist standpoint, evolutionary considerations probably deserve special status in understanding intelligence. Yet theorists of intelligence probably have devoted the least attention to them.

CONCLUSION

In sum, the proposal here is that three criteria for understanding the nature of intelligence are nonarbitrary, given a definition of intelligence as broad adaptation to the environment. The first is correlation of a target thought or behavior with cultural success (cultural adaptation). The second is mental skills development (cultural and biological adaptation). The third is evolutionary origins and development (biological adaptation). This book examines the third and, arguably, most important of these three criteria, the evolutionary one.

ACKNOWLEDGMENTS

Preparation of this chapter was supported by Grant REC-9979843 from the National Science Foundation and by a grant under the Javits Act Program (Grant No. R206R000001) as administered by the Office of Educational Research and Improvement, U.S. Department of Education. Grantees undertaking such projects are encouraged to express freely their professional judgment. This chapter, therefore, does not necessarily represent the position or policies of the National Science Foundation, Office of Educational Research and Improvement or the U.S. Department of Education, and no official endorsement should be inferred.

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