Nature/nurture: Integration through constructivism?

The question addressed by Quartz and Sejnowski in this book is how the brain develops the neural organization that allows complex behavioral capabilities, including those identified as properties of mind. In contrast to more deterministic viewpoints holding either that there are genetic ‘‘blueprints’’ for precisely designed brain modules (evolutionary psychology) or that human behavior is entirely reflective of culture (cultural relativism), Quartz and Sejnowski approach the question from the theoretical perspective of neural constructivism. Here, the emphasis is on the flexibility of the developmental process, a flexibility that is inherently constituted by the system comprised of genes in interaction with their environment. They propose that this is the way in which human culture helps to build the precise circuitry of the brain that enables the construction of symbolic models of the world. The following review will provide an overview of the ideas presented in the book, concluding with a discussion of the issues seen to be of particular interest to developmental psychobiologists. An integral theme of the book is how evolutionary theory, including the so-calledmodern synthesis, has been used to support various ideological positions with respect to the role of biology in human affairs. Inherent to Darwinian thought is the notion of progress based on the struggle among individuals, and the transmission of individual traits that confer reproductive advantage. The modern synthesis challenges these ideas on two fronts. First, as historical events have conspired to undermine the notion of human progress, so too has evolution come to abandon the concept of an overall plan in favor of random contingencies. Second, the identification of the genetic code and the subsequent investment of resources in the Human Genome Project have resulted in a shift in emphasis away from the individual towards the gene as the unit of selection, where the competition for survival into the next generation is seen to be among ‘‘selfish genes’’ rather than among individuals. There has been considerable fluctuation in opinion during the 20th century on the relative importance of biology to human behavior. Following the dismissal of Social Darwinism at the turn of the century, empiricist theories emphasizing the role of experience and culture gained ascendancy. In contrast, work on animal behavior, and in particular the studies conducted by ethologists, continued to be informed by a biological perspective. This work advanced the understanding of ecological adaptations, thereby providing a framework for the theory of Sociobiology. According to this theory, behaviors (including those of humans) are seen as precise adaptations to a species-typical ecological niche, recognizing that the nature of the social interactions within a species contributes to the defining attributes of such a niche. Both altruistic and aggressive behaviors are viewed as innate responses that are elicited by specific social contexts. There has been strong reaction to these ideas by many people who associate them with infamous eugenic policies of the 20th century. They have nonetheless been influential in the subsequent development of the thinking now characterized as Evolutionary Psychology. In contrast to Sociobiology’s view that human nature represents an adaptation to modern life, Evolutionary Psychology views brain and behavior as adaptations to an ancestral environment. The brain is seen as a collection of specializedmodules that have served us well in the past (‘‘Swiss Army Knife’’), but which may contribute to our being misfits in the modern world. Furthermore, oversimplistic reports by the popularmedia (and sometimes by the scientific community) of finding ‘‘the gene for’’ various ailments that plague humankind have fueled public imagination with respect to overriding importance of the gene in specifying the nature of these hypothetical modules. This has in turn led some to postulate that it may be possible to change various socially aberrant behaviors merely by altering genes. Received 18 March 2004; Accepted 31 March 2004 Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/dev.20017