NATURE VIA NURTURE

More on the ongoing debate of whether heredity or environment is in charge of who we are, from the assertive but knowledgeable English science writer Ridley.

Rather than just another exercise in stating the mutual dependence/interaction of genetic and environmental factors, the author provides examples of new-found genes that may turn on or off, may be more or less active, may or may not trigger a cascade of other gene actions, depending on circumstances. Nor is “the gene” always well-defined, he states. It can often be spliced in multiple ways, using alternative forms of component parts (the exons) with variable effects in various tissues. So, on the gene side, much variety, and on the nurture side, contexts galore, creating circles of complexity and feedback that render cause-effect statements (à la determinism) moot. Ridley’s examples and inferences include genes and their mutations in the course of evolution that influence brain size and neuronal connections, personality, sexuality, language, culture, aggression, and nurturance, but still operate as cogs in the wheel of experience. Ultimately, he declares in favor of free will. He avers that we must replace linear with circular causality, “in which an effect influences its own cause”—sounding just like a physicist talking about quantum mechanics. Before reaching that point, Ridley cites a dozen graybeards over the century who have kept the N/N debate alive, with some kind remarks for Boas and Durkheim, even Lorenz and Tinbergen, but excoriation for Freud, Skinner, and Watson. Trouble is, for all Ridley’s celebration of mutuality, some of the evidence he cites, such as twin studies, comes down strongly in terms of genes determining personality; while other data suggest that prenatal and infant experience (albeit via environmental influences on genes) are irrevocable.

Certainly not the last word, but a lot of interesting turns of phrase and provocative findings to enrich the all-absorbing study of genes and behavior.