Matt Ridley. Nature via Nurture (2004)

     Matt Ridley. Nature via Nurture (2004) Argues and demonstrates that the dichotomy of Nature vs Nurture is not merely wrong, it’s profoundly misleading. The genes can operate only in response to nature (here broadly defined as the environment in general, including anything outside the cell itself, that is, including the rest of the body). And nurture can’t have its effects if there are no genes to respond to it. Much interesting bleeding-edge research supports this thesis, and there is perhaps more repetition of the thesis than strictly necessary. However, Ridley’s point is well-taken. On philosophic or logical grounds alone, the “nature versus nurture” argument is silly, since it’s obvious that any organism must be equipped to survive, which means that it must develop the requisite organs and behaviours. In other words, it must respond properly to it environment, hence nurture plays a role. But it can respond properly only if it has the proper genetic endowment, hence nature plays a role. The only puzzle is how nature and nurture interact to produce a viable organism.
     Ridley reviews what’s now known about this interaction, and in doing so suggests a fundamental shift in perspective. He stresses the role of genes in the development of an organism (and corrects the genome-as-blue-print metaphor as he does so). The most important single point I think is that the environment switches genes on and off in a fixed sequence during development, and that once a gene’s work is done, it usually cannot be reactivated. Moreover, it’s the timing of gene activity, i.e., how long it persists, what other genes are activated or not at the same time, etc, that determine the adult’s phenotype. These two factors, timing and sequencing, have lifelong effects, almost always irreversible. Yet each stage of development depends on environmental cues, both external to the organism, and internal (in the form of proteins etc produced by other genes’ actions).
     I think that it’s the rigidity of developmental response to the environment that encourages people to think that nature is all. For if nurture could have unlimited effects, it could change the organism at any time. This latter notion is said to be the dogma of radical behaviourism, and certainly Skinner was rash enough to make such claims in language that make them sound silly. No amount of Skinnerian conditioning can make a Newton; but given a Newton, an environment that suited him was essential to enable the kind of discoveries he made (including the ones histories of science ignore). In pushing his point of view, Skinner rarely made his underlying assumption explicit, that an organism’s behaviour can be shaped by the environment, but cannot be created by the environment. An organism must “emit” a behaviour, in the quaint jargon of the behaviourists; only then can behaviourist techniques shape it. Just where the emitted behaviour comes from is not a behaviourist concern, apart from denying that some non-material mind or soul causes it.
     Ironically, the neurologists’ methods and stance are thoroughly behaviourist: they investigate behaviour in terms of responses at the neural and even molecular level. Their results show that even at these levels, the environment shapes behaviour. The organism develops and exists as a pattern of interaction with its environment. Yeats said, Who can tell the dancer from the dance? Flip Wilson said, What you see is what you get. Marshall McLuhan says We construct the truth about the environment by building the environment with which we interact.  I say The self exists as the interface between inner and outer. These are I think different ways of saying that nature and nurture act together to make us what we are.
     Ridley makes other points along the way. One is that the one-gene-one-protein concept is thoroughly wrong. Proteins may be built (are usually built in fact) by several genes acting together. A single gene can be (usually is, in fact) implicated in the building of several different proteins. A gene may be (often is, in fact) partially activated, so the same gene can build different proteins at different times, even when acting alone. Moreover, a protein’s effects depend on the existence of other proteins, so that genes affect each other’s expression. Finally, since the expression of a gene is not a simple straight-line chain of cause and effect, but a complex web of interwoven strands and feedback loops, genes’ effects both cancel and complement each other, so that a single mutation rarely has a serious effect, or even a visible one. It’s no accident that so few diseases have been traced to the mutation of single genes.
     These facts explain why genetic engineering has been so unsuccessful thus far. One would think that, with hundreds of millions spent on R&D, by this time we would have hundreds of varieties of GE plants, but it seems that most of the time the efforts fail, a fact that is curiously not widely publicised. Or perhaps not so curiously: neither the promoters nor the opponents of GE want the public to know the high failure rate, for opposite but thoroughly complementary reasons. Each side exaggerates the success of GE, one to generate enthusiasm, the other fear. However, those who advise caution have a good case: we don’t really know what the insertion of a foreign gene will do in an organism, since there are too many ways in which a gene’s expression will be controlled or affected by the other genes.
     Good book. **** (2004)