Nature Plus Nurture

As early as the 1970s, Cattell spoke of the human’s “capacity to acquire new capacity” (1971, p. 8), alluding to the marvelous ability human beings have to actually change their own capacity. We can become more than we were at birth—not more in the sense of exceeding the limits of our inborn characteristics of physical structure, but most certainly more in our ability to use those characteristics and that structure. In some cases, we may modify the total to become more efficient and more powerful than these limits seemingly dictated. We have not properly appreciated the ability of our organism to expand or decrease as it interacts with the environment. As Diamond (1998) states, “The brain, with its complex architecture and limitless potential, is a highly plastic, constantly changing entity that is powerfully shaped by our experiences in childhood and throughout life. . . . Our collective actions, sensations, and memories are a powerful shaper of both function and anatomy” (pp. 2–3) [Emphasis that of the author].

Neurobiologist Teyler explained in 1977:

The fabric of the brain is set down as a result of the interaction of genetic blueprints and environmental influences. While the basic features of brain organization are present at birth (cell division is essentially complete), the brain experiences tremendous growth in neural processes, synapse formation, and myelin sheath formation, declining around puberty. These processes can be profoundly altered by the organism’s environment. Furthermore, it has been shown that brain processes present at birth will degenerate if the environmental stimulation necessary to activate them is withheld. It appears that the genetic contribution provides a framework which, if not used, will disappear, but which is capable of further development given the optimal environmental stimulation. (pp. 31–32) [Emphasis that of the author]

Genes cannot be thought of as causing particular attributes; rather, they have a wide range of effects in different environments. Genes do not make specific bits and pieces of a body; they code for a range of forms under an array of environmental conditions. Moreover, even when a trait has been built and set, environmental intervention may still modify what has been inherited.

Even our beliefs about the absolute stability of genes must be reexamined. Genes provide us with a structure or pattern, but are dependent on the environment for the particular characteristics that they will express. While genes provide us with our own unique menu, the environment makes the actual selection within that range of choice.

It is misleading to think of either genes or the environment as being more important: Genes can express themselves only in an environment, and an environment has no effect except by evoking genotypes already present. Restak (2003) concludes that no matter how powerful the genetic inheritance, the environment must be conducive to the development of a particular talent for it to develop to high levels. Any reference to high-IQ genes must be seen as a misnomer. It would be equally incorrect to regard genetic endowment as “setting the limits.” Siegel (1999), Medical Director of the Infant and Preschool Service and Associate Clinical Professor of Psychiatry at the University of California, Los Angeles, School of Medicine concludes:

An infant is born with a genetically programmed excess in neurons, and both genes and experience determine the postnatal establishment of synaptic connections. Genes contain the information for the general organization of the brain’s structure, but experience determines which genes become expressed, how, and when. (p. 14) [Emphasis that of the author]

A wide range of studies over several decades has now supported the fact that development is a product of the effect of experience on the unfolding of genetic potential (Diamond, 1988; Edelman, 2004; Hawkins, 2004; Kandel, 2006; LeDoux, 2003; Rosenzweig, 1966; Siegel, 1999).

The interaction between genetic and environmental contributions is complex and interdependent. Throughout this text, our exploration of this interaction focuses on the environment. This one-sided focus reflects our ability as educators to influence growth and development only from the environmental realm. We provide environments to deliver learning experiences, so we must be aware that decisions about those environments do, in fact, change the neurological and biological structure of our students.

Environmental interaction with the genetic program of the individual occurs whether it is planned or left to occur by chance. We already know enough about supportive environments to ensure that most of our children attain a level of functioning that would actualize far higher levels of intellectual ability. Yet, because of society’s priorities, social dilemmas, and lack of parental training, we do not use what we know.