Biology and Culture: A Two-Way Street of Causation A review of [book cover] <#> *Lifespan Development and the Brain: The Perspective of Biocultural Co-Constructivism* by Paul B. Baltes, Patricia A. Reuter-Lorenz, and Frank Rösler (Eds.) New York: Cambridge University Press, 2006. 444 pp. ISBN 978-0-521-84494-9. $90.00 ------------------------------------------------------------------------ Reviewed by Michael Cole Cole, Michael S-1 #1 More than six decades ago, developmental psychologist Arnold Gesell (1945, p. 358) declared that “Neither physical nor cultural environment contains any architectonic arrangements like the [biological] mechanisms of growth. Culture accumulates; it does not grow. The glove goes on the hand; the hand determines the glove.” It is difficult to imagine a clearer statement of the unidirectional causal relation between phylogeny and culture. Cole, Michael S-1 #2 Thirty years later, anthropologist Clifford Geertz (1973), surveying extant knowledge of human origins in which it appeared that manifestations of culture were evident in the phylogenetic record for millions of years, argued for the constitutive role of culture in the biological composition of modern humans: Man's nervous system does not merely enable him to acquire culture, it positively demands that he do so if it is going to function at all. Rather than culture acting only to supplement, develop, and extend organically based capacities logically and genetically prior to it, it would seem to be ingredient to those capacities themselves. A cultureless human being would probably turn out to be not an intrinsically talented, though unfulfilled ape, but a wholly mindless and consequently unworkable monstrosity. (p. 68) Cole, Michael S-1 #3 The book /Lifespan Development and the Brain: The Perspective of Biocultural Co-Constructivism/ provides a plethora of data to support Geertz's prescient manifesto. The contributors dub this view “biocultural co-constructivism,” the view, in their words, that “all entities involved in the development of brain, behavior, and culture are deeply interwoven and influence each other in cumulative ways” (p. 13). A second message, which has been the major theme of Paul Baltes's work over many decades, is that development does not stop following puberty but continues for as many decades more that the person continues to live. Cole, Michael S-1 #4 Several key ideas and areas of research are brought together in this volume in support of the editors' central theses. These include the following: 1. The pioneering work of Hebb on the increased behavior capacities that are induced when laboratory rats are freed from their cages to engage with rich and challenging environments and Mark Rosenzweig and his colleagues' subsequent evidence that such environmentally induced behavioral capacities have their counterparts in neural growth characterized by increased synaptic connections and other biological indicators of enhanced neuronal functioning (summarized in Rosenzweig & Bennett, 1996). 2. A variety of research on neurogenesis, including the now-familiar evidence that the developing brain produces an overabundance of neurons that are selectively pared away or consolidated depending on later experiences and new evidence of neurogenesis and changes in the brain's microanatomy far into adulthood and possibly into old age. 3. A rapidly expanding body of research of neuronal plasticity and the consequent recognition of the potential multifunctionality of brain regions exhibited in cases, such as blindness or deafness in which brain areas deprived of sensory input from the evolutionarily typical sources reorganize to become additional resources to support and amplify remaining capacities (as when the visual cortex begins to respond to auditory input among the congenitally blind). 4. A variety of research demonstrating that specific cultural practices (e.g., learning to read in school, driving a taxi for several years in London) are associated with measurable differences in the anatomical structure or functioning of specific brain regions known to be implicated in the associated form of activity. Cole, Michael S-1 #5 The book provides excellent summaries of specific areas of research contributing to the overall thesis of lifespan biocultural co-constructivism. I found that one of the most interesting aspects of this book is the evidence that the field still faces serious challenges in coming to grips with the problem of specifying in appropriate detail the environmental side of the bidirectional process and, when dealing with humans, with specifying what is meant by a cultural influence. This difficulty shows up in different ways in different chapters. Cole, Michael S-1 #6 With respect to research on the environmental impact on brain development in rats, for example, Charles Nelson notes that the term /enrichment/ is a relative one, but then goes on to write that in the well-known studies of enriched (more complex) environments, the experimental environments are enriched “relative to the typical environments in which most rats live” (p. 72). In fact, the enriched environments studied in the laboratory are almost certainly less complex than the environments that a vast majority of the world's rats live in outside of scientists' laboratories, and their behavior in such environments is sufficiently intelligent to defy the best efforts of exterminators from New York to Mumbai to eradicate them. Cole, Michael S-1 #7 This same difficulty in situating environmental effects vis-à-vis behavioral (and presumably brain) processes appears again when Nelson comments that the enriched environments of rats are “all encompassing” whereas interventions with human children such as Head Start are not all encompassing so that “specific, narrow, effects, such as an increase in IQ” (p. 73) cannot be reasonably expected—all the more so because such children spend more time at home than at school, “and thus, the deprivation effects inherent in the home environment may eventually overwhelm the effects of early enrichment [in school]” (p. 73). To those engaged in the debates about heritability of /g/ and the many anthropologists who have documented the social complexity of the home life of children attending Head Start programs, these kinds of judgments are likely to seem improbable. (Which in no way detracts from the great importance of the work by Nelson and his colleagues on the effects of being raised in a Rumanian orphanage, which promises to shed important light on brain-experience relationships.) Cole, Michael S-1 #8 Other chapters, each excellent in their review of their respective topics, display similar uncertainties when it comes to explaining what is specifically cultural about clear experience-expectant and experience-dependent effects on brain development and just how specific such cultural effects might be. For example, Ptito and Desgents's well-crafted review of ways in which brain architecture changes to adapt to or compensate for disrupted sensory input or the catastrophic condition of hemispherectomy underlines the evidence that the spared hemisphere “plays a role in the mediation of many residual abilities, such as motor and sensory (vision and somesthesis) behaviors” (p. 129). But extant evidence, such as Antonio Battro's (2000) study of a child who underwent a hemispherectomy at the age of 3, indicates not only that vision and somesthesis can be supported by the remaining hemisphere but that such higher, clearly culturally mediated functions such as literacy, numeracy, and all-but-normal language development can be induced in the remaining hemisphere given a proper culturally organized regime of enriched experience. Cole, Michael S-1 #9 The idea that dense, culturally organized experience can produce neural specialization is also supported by two chapters devoted to the impact of reading, writing, and arithmetic instruction on brain processes. As researchers in this area, following Alexander Luria, point out, literacy and numeracy are recent developments on an evolutionary scale and require years of systematic instruction. Current evidence seems compelling, however, that as a result of such instruction, there is, in Polk and Hamilton's phraseology, “the development of new functional brain areas that perform functions acquired through experience” (p. 195). A similar conclusion is supported by Petersson and Reis's chapter comparing responses to verbal tasks of middle-aged women who did or did not attend school as youngsters decades earlier. Cole, Michael S-1 #10 An important task confronting this line of research is to determine in more detail the generality of the observed effects: Do the effects of learning to read and write extend beyond the development of highly specialized systems for analyzing words (or numbers?). Or, as is the case with acquisition of expertise in use of the abacus, are the effects highly specific to their corresponding tasks? Some degree of generality is to be expected at the behavioral level, if only because reading, writing, and numeracy are components of a variety of cultural practices to which they can make important adaptive contributions (children who master calculation on an abacus also perform better on some arithmetic problem-solving tasks because the calculational part of the task has been automated so that they can devote less attention to it). Something of the same effect ought to be expected in relation to the brain consequences of literacy and numeracy, but so far the evidence is lacking. Cole, Michael S-1 #11 In this regard I found especially interesting Vitouch's evidence that high levels of musical training may result not only in changes in brain architecture but also in changes with wide-ranging effects in the domain of music. It is not only that skilled violin players show changed architecture for brain regions subsuming the fingers of the right (not the left) hand, but also that people who have undergone extensive musical training may well undergo generalized changes in aesthetic experience (associated with music, to be sure). Cole, Michael S-1 #12 These are only a few of the fascinating phenomena and important challenges to psychological science presented in this important book. /Lifespan Development and the Brain/ should be required reading for a broad range of psychologists well beyond the devotees of life-span developmental psychology or the study of the causal mechanisms of brain-behavior relationships. It is perhaps the first book of its kind to deliver on the longstanding promise that by combining the study of phylogeny with the careful study of the organization of people's activities in everyday life, psychology actually overcomes the false dichotomy of nature versus nurture in fact as well as in words. ------------------------------------------------------------------------ References Battro, A. M. (2000). /Half a brain is enough./ New York: Cambridge University Press. Geertz, C. (1973). /The interpretation of cultures./ New York: Basic Books. Gesell, A. (1945). /The embryology of behavior./ New York: Harper & Row. Rosenzweig, M. R., & Bennett, E. L. (1996). Psychobiology of plasticity: Effects of training and experience on brain and behavior. /Behavioral Brain Research/, /78/, 57-65. ------------------------------------------------------------------------ PsycCRITIQUES February 28, 2007 Vol. 52 (9), Article 9 *1554-0138* © 2007 by the American Psychological Association For personal use only--not for distribution.