WHAT DOES IT MEAN WHEN WE SAY SOMETHING IS “INNATE”?

WHAT DOES IT MEAN WHEN WE SAY

abilities of different species. However, as was the case with Darwin, Roma- nes’s work was limited by a lack of a theory of inheritance. But as the mechanisms of genetics became more widely accepted and as the modern synthesis took shape in the 1930s and 1940s, a new group of biologists, the ethologists, began to scrutinize animal behavior from an explicitly evolutionary perspective. Ethologists studied the behavior of animals, mostly in their natural habitat. Like contemporary evolutionary psychologists, they looked for species universals-behavior that characterizes all normal members of a species at some time in their development, or perhaps all members of one sex of a species-and interpreted those behaviors in an evolutionary framework, specifically, in terms of what adaptive function those behaviors may have. The careful observations, field experiments, and innovative theo- rizing gained the three pioneers of this field, Konrad Lorenz (1903-1989), Niko Tinbergen (1907-1988), and Otto von Frisch (1886-1982), the Nobel Prize in Physiology or Medicine in 1973, the only behaviorists ever to receive such a distinction.

We introduced some of the ideas of Tinbergen (1963) in chapter 2, specifically his four questions that we must ask to fully understand any behavior: What is the immediate benefit (adaptive function) of a behavior?

What are its causes? How does it develop? How

did

it evolve? But ethologists’

most important contribution with respect to the “innateness” issue was the concept of instincts. The classic demonstration of instincts comes from the work of Lorenz (1937, 1965) with geese. Lorenz observed that, hours after hatching, goslings would follow the first moving thing that they saw. (Later research indicated that auditory cues were of even greater importance; see Hess, 1973.) Usually the first moving and noise-making object in a young gosling’s life would be that of its mother. In the wild, the goslings would stay close to their mother, which has obvious survival value. But if during this critical period the goslings see not their mother but a human being, they

will

follow that person, much as they would their mother. Lorenz called this phenomenon imprinting. No prior experience is necessary for this phenomenon, and once the image of the mother goose (or Lorenz himself) is “imprinted” in the gosling’s brain, it cannot be altered. From this research, the idea that a complex and adaptive behavior could be “built into the genes” and elicited by a particular experience at a particular time, became the canonical definition of instinct.

Tinbergen (1951) described a particular class of instincts as fixed- action patterns, stereotypic behavior patterns that are elicited

by

a specific environmental event. This pattern is like a complicated reflex that, once evoked, runs its course. The difference between a fixed-action pattern and a reflex is mainly in the complexity of the behavior. A classic example of a fixed-action pattern was provided by Tinbergen (1951) for the male stickleback fish, described briefly in chapter

2.

Tinbergen noticed that, at

times, male stickleback fish behaved aggressively toward other males in their territory. Specifically, they acted aggressively when the invading male had a red belly, which signals readiness to mate. But he also noticed that males would make aggressive displays when other red objects entered their line of vision (including a red truck passing the window where the

fish

tank sat). Through a series of experiments, Tinbergen demonstrated that it was the red spot that elicited the stereotypic aggressive behavior of the stickleback fish.

This

^isnormally highly adaptive in the

wild,

in that the presence of a red spot is typically a sign of a sexual competitor. But it is a thoughtless

“instinct,” programmed into the brain of male stickleback

fish

that can he aroused under experimental circumstances that are totally unrelated to the purpose for which the response had evolved.

Instincts for the early ethologists were examples of genetic determinism, or genes ⁺behavior. Complicated behaviors are preprogrammed and,

by

definition, no experience is necessary for these behaviors to be realized.

Experience

did

play some role, of course. For example, goslings were not genetically programmed to imprint to their mother, per se, but rather were programmed to imprint to the first moving thing they saw at a particular time in development which, in the natural world, would inevitably be their mother. The genetic determinism of the early ethologists relegated relatively little role to development. Although certain experiences may he necessary at specified times in ontogeny (i.e., critical periods), behavior was “innate”

and would be expressed when the animal was exposed to the proper environmental cues.

We saw in our discussion of the developmental systems approach in chapter

2

that even such “instinctive” behavior as imprinting in precocial birds is not uninfluenced

by

experience. Rather, as Gottlieb

(1976, 1997)

and many others (see Gottlieb et al.,

1998;

Kuo,

1967;

Lehrman,

1970;

Schneirla,

1960)

have demonstrated, prenatal experience, specifically hear- ing a species-typical call, plays a critical role in whom a baby bird will approach and follow. Moreover, other research has demonstrated that imprinting is not as permanent as Lorenz had believed (see Cairns,

1979;

Hess,

1973).

Rather, later experiences (i.e., after the “critical period”) can modify a previously “imprinted” response, illustrating the flexibility of such “instincts”

(Bateson, 1981b).

Although the early ethologists’ observations of complex behaviors elicited

by

specific environmental events advanced the understanding of animal behavior immeasurably, their interpretation of “no experience necessary” and “no flexibility” for such behaviors was incorrect, something that later ethologists recognized (Hinde,

1980).

However, the ethologists’ original definition of instinct is still with us today. Although we believe that most ethologists and comparative and developmental psychologists recognize that the “no experience necessary” definition of instincts is untenable, many 64 THE ORIGINS OF HUMAN NATURE

other psychologists, and nearly all laypeople, implicitly continue to accept this view of instincts and thus of innateness.

However, for many people concerned exclusively with human behavior, this is not a substantial problem because many students of human behavior continue to hold the position, perhaps advocated

by

a majority of behavioral scientists only several decades ago, that humans have no “instincts”-that Homo supiens possess no specific innate mechanisms other than a large brain and a general ability to learn.

Standard Social Science Model

Although ethological theory

did

influence the thinking of some scientists concerned with human behavior and development (Bowlby,

1969; Eibl-

Eibesfeldt 1989; Hinde,

1974;

McGrew, 1972), most research in ethology was devoted to nonhuman animals. Moreover, for much of the 20th century, any form of biological causation with respect to human behavior, including evolutionary accounts, was anathema to the academic mainstream. Evolu- tionary psychologists John Tooby and Leda Cosmides

(1992)

labeled the dominant antibiological perspective of human behavior the Standard Social Science Model

(SSSM).

According to Tooby and Cosmides, the

SSSM

basically denied the existence of a human nature. Human beings come into the world with the ability to gather and interpret perceptual information and a general capacity for learning. Biological evolution as a sculptor of human behavior and thought is replaced

by

cultural evolution.

Although we think that Tooby and Cosmides’s (1992) depiction of the ubiquity of the

SSSM

is a bit overstated, we fully agree with their observation that, until relatively recently, majority opinion in Western academe has been one of cultural determinism. Our own undergraduate educations were steeped in this perspective. We were taught that humans have no instincts, or innate predispositions. Infants were essentially blank slates; even their smiles were just arbitrary behaviors that had become conditioned to positive events.

All

sex differences other than those directly related to reproduction were culturally arbitrary. People in different cultures around the world were far more different than they were similar, and the pressure to conform to local social norms and mores determined such behavior.

The hegemony of the cultural-relativism perspective cut across the social sciences, including developmental psychology. One reason for the dominance of this position in developmental psychology was the emphasis that the field put on early experience. Learning theories such as those of John Watson (1878-1958) and

B. F.

Skinner (1904-1990) equated development with learning and held that that which is learned early sets the course for later development. Even theories that assumed that children possessed

a biological nature, such as Freud’s theory of psychosexual development, stressed the role that early experience plays in forming personality. And when Piaget’s cognitive theory began to replace behaviorism as a model for intellectual development, the emphasis, in the United States at least, was on early development, particularly how parents or educators could best establish intellectual competencies in children, which would presumably be maintained thereafter (Hunt, 1961; White,

1978).

There was little room for any hint of biological influence in such perspectives.

Related to this viewpoint of developmental psychologists is what Charlesworth (

1992)

referred to as meliorism.

Child

developmentalists have long been concerned with fostering development in children, beginning with the child study movement established by Hall at the beginning of the 20th century (Cairns,

1983).

The goal of improving children’s lives fits well with a strong behaviorist perspective. The “child welfare” agencies that were established at Iowa and Minnesota were an outgrowth of this orientation.

If

early experience is responsible for establishing social, emotional, and intellectual competence, science can discern what those experiences are and develop programs to provide all children with them.

If,

in contrast, important aspects of behavior are determined

by

genes, behavioral interven- tion can have little influence.

If

it is in the genes, it is presumably not subject to modification. Moreover, any suggestion that socially consequential behaviors such as aggression, personality, and intelligence are innate implies the existence of biologically defined categories of people. Smart people and aggressive people are that way “by nature,” raising the possibility of a genetically based caste system, the antithesis of modern liberal democracy.

This is also related to the nuturulisticfullacy-the false belief that if something has evolved and is “natural” it must be morally ‘(right.” Such a view under- standably makes the acceptance of evolutionary interpretations for certain aspects of human behavior (e.g., aggression) undesirable. However, evolu- tionists do not equate what is “natural” with what is “right,” and neither should anyone else, thus making untenable the argument that evolutionary explanations for human behavior or development are morally reprehensible (see Thornhill & Palmer,

2000;

also chapter 6).

Even strong proponents of a ‘(gene’s eye view” of behavior (i.e., proponents of gene ⁺behavior viewpoints) do not support the idea of genetic determinism. For example, Richard Dawkins

(1982),

one of the architects of sociobiology and a believer that our social behavior (such as altruism), is greatly influenced by genetics, discounts such a claim:

People seem to have little difficulty in appreciating the modifiability of

“environmental” effects on human development. If a child has had bad teaching in mathematics, it is accepted that the resulting deficiency can be remedied by extra good teaching the following year. But any suggestion that the child’s mathematical deficiency might have a genetic

66

THE ORIGINS OF HUMAN NATURE

origin is likely to be greeted with something approaching despair: If it is in the genes, “it is written,” it is “determined” and nothing can be done about it. This is pernicious rubbish on an almost astrological scale.

Genetic causes and environmental causes are in principle no different from each other. Some influences of both types may be hard to reverse;

others may be easy to reverse. Some may be usually hard to reverse but easy if the right agent is applied. The important point is that there is no general reason for expecting genetic influences to be any more irreversible than environmental ones. (p. 13)

Cultural relativism continues to hold a strong position within the social sciences but, over the past several decades, emphasis on biologically based accounts of behavior and development has increased. This can be seen in research in language development that has demonstrated that children do not learn language via the rules of operant and classical conditioning, but rather are “prepared” to acquire the language spoken around them (Pinker,

1994;

6);

in work in behavioral genetics that illustrates that many aspects of cognition and personality are highly heritable (McGuf- fin, Riley, & Plomin,

2001);

and in evidence showing that infants are not born as blank slates, but come into the world with certain “knowledge” and expectations about what type of environment they can expect (Spelke &

Newport, 1998; see also chapter

6).

This

increased acceptance of biological causation requires that researchers develop more precise theories about what it is that is inherited.

That is, when child developmentalists essentially rejected any idea of innate abilities in their subjects, it mattered little how they defined innateness. Now that biologically based accounts of development, including evolutionary accounts, are being taken more seriously, it is necessary to examine more closely what we mean when we say that something is innate.

Contemporary Conceptions of Innateness

For contemporary developmental psychologists, the term innate can be contentious, and many would just as soon not see it used at all. This is because “innate” is often seen as being equivalent to “instinct,” which is interpreted

by

many not much differently from the way the early ethologists interpreted it, that is, as complex behavior requiring no prior experience for its expression.

As

should be clear by now, this is not what developmental psychologists today mean when they speak of “innateness,” when they speak of it at all. For evolutionary developmental psychologists, the term can have a range of meanings, depending on the characteristic under study.

As

with physical characteristics, some innately influenced behaviors can be highly canalized, that is, they are likely to be expressed in all but the most extreme environments, whereas others can be less specifically directed by the genome.

Our own perspective is consistent with the developmental systems approach described in chapter

2.

This perspective views development as being the result of the bidirectional interaction at all levels of organization, from

DNA

⁺⁺

RNA,

through the individual and his or her culture (see Gottlieb,

1998,2000;

Gottlieb et al., 1998;

Ho, 1998; M. H.

Johnson, 1998).

The functioning of the organism itself, as in the firing of neurons, is a form of experience that influences subsequent development. From this perspective, there can be no pure genetic-biological or environmental-social effects on development. Everything must be conceived as the result of the continuous and bidirectional interchange between structure and function, operating at all levels of organization, over the course of development. From this perspective, there is neither biological nor environmental determinism. Rather, development is probabilistic. Genes are part of the developmental system, but they are not immune to influences from other levels of the system.

Nevertheless, different members of a species usually develop to be highly similar to one another. That is, despite the probabilistic nature of development, species-universal behaviors exist. Gottlieb (

1997)

presented his position as follows:

The resolution I have opted for in this volume is to accept that certain developmental outcomes are species-typical or species-specific, adaptive, and responsive to a narrow class of stimulation in the absence of prior exposure to these configurations (independent of frank learning but not independent of experience, broadly defined). (p.

144)

As

we view it, from a developmental systems perspective, one cannot speak of innateness without considering genetics, environment broadly defined, and the continuous interaction of these factors.

Genes, of course, interact with their environment at a variety of levels, and some researchers have proposed that we restrict “innate” to changes that arise as a result of interactions occurring within the organism. For example, we may inquire about the extent to which some neural circuits are the products of interactions strictly within the organism, seemingly uninfluenced by the external environment

(M. H.

Johnson, 1998;

M. H.

Johnson & Morton, 1991). This perspective is consistent with the idea of constraints, discussed briefly in chapter

2

and in greater detail in chapter

6

(Elman et al.,

1996;

Gelman & Williams, 1998; Spelke & Newport,

1998).

When applied to the human mind, the idea of constraints is that humans (or any species) are limited in how they can make sense of their world.

Such limitations, however, permit individuals to specialize. Rather than having a general-purpose mind that must be applied to every problem it encounters, individuals have specialized programs that are able to solve certain problems exceptionally well (e.g., acquiring language), but little else.

68 THE ORIGINS OF HUMAN NATURE

From this perspective, processing constraints enable learning rather than hinder it.

Within this perspective, there are different kinds of constraints, with different implications for what it means for something to be innate. For example, in Rethinking Innateness, Jeffrey Elman and his colleagues (1996) proposed three general types of constraints: representational, architectural, and chronotopic. These constraints vary in the extent to which they are genetically specified. Representational constraints are the most highly specified and refer to representations that are hardwired into the brain so that some types of “knowledge” are innate. For instance, several neonativist theorists have proposed that infants come into the world with (or develop very early in life) some basic ideas about the nature of objects (e.g., their solidity), mathematics (e.g., simple concepts of addition and subtraction), or grammar (see Pinker,

1997;

Spelke & Newport,

1998;

Wynn,

1992).

Specific synapses are “preprogrammed” to process certain types of information. However, unlike earlier instinct theorists, neonativists advocating representational constraints do not propose that this innate knowledge is independent of experience. Experience and maturation of the brain (which itself is a complicated process involving the bidirectional relation between neurons, their immediate surroundings, and their own excitation) play a role in shaping this knowledge, but most proponents of representational constraints believe that infants come into the world with domain-specific neuronal representations.

This

does not mean that there is no development; everything develops.

But, according to this perspective, children (and other animals) are born able to make sense of certain aspects of their environments (e.g., basic notions of physics, how to build webs if you’re a spider) given only minimal postnatal experience.

According to Elman et al.

(1996),

architectural Constraints represent an intermediate degree of genetic specificity and refer to ways in which the architecture of the brain is organized at birth. For example, neurons can have different functions (some being excitatory, others inhibitory) or can vary in the amount of activation required for them to fire. At a somewhat higher level, neurons in a particular part of the brain might be more or less densely packed or have many or few synapses with other local neurons.

And at a higher level yet, different areas of the brain are connected with other areas of the brain, affecting global organization. Architectural constraints limit the type and manner of processing the brain can perform, not because the brain comes equipped with innate representations (e.g., what grammar is), but because certain neurons or locations of the brain can process only certain types of information and pass it along to certain other parts of the brain. Thus, architectural constraints imply limits on what is processed, as do representational constraints. Unlike representational

Dalam dokumen The Origins of Human Nature Evolutionary Developmental Psychology (David F. Bjorklund, Anthony D. Pellegrini) (Halaman 66-75)