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1. Reading Assignment
The Rise of Neurogenetic Determinism by Steven Rose Nature 373: 380-382 (1995)
As a complement to Biology as Ideology we will also read an article on reductionism since many of the studies on biosocial problems have an implicit reductionist assumption.
What do we mean by the term " reductionist ?" We will develop this idea more fully in class, but let me provide you with an introduction to this term. Probably the simplest definition of reductionism is the belief that all biological phenomena can be explained by referring to the laws of chemistry and physics. This sounds reasonable if a bit abstract, but let us examine a more concrete reductionist approach as an example.
Basically reductionsim is the attempt to identify simple causes of complex phenomena. Reductionism is a very powerful idea, and indeed, much of what we do in science is only possible with a reductionist approach that allows us to design experiments and studies that give clear answers. However, this is also the weak point of reductions. Let me give you two examples.
Let us say we would like to know the effect of the hormone insulin on the expression of a given gene (gene X). We can grow cells in tissue culture, and, holding all other variables constant, we can vary the level of extracellular insulin and measure the amount of gene X RNA produced in a given time period. Such an experiment would allow us to say something very concrete about the dependency of gene X transcription on insulin. The problem is that in cells under natural conditions, we have multiple variables changing simultaneously. As insulin levels rise, glucagons levels drop and circulating glucose and free fatty acid levels also change. Indeed, many different molecules may change simultaneously as insulin levels change so that the actual in vivo effect of insulin may be quite different from that we determined in our carefully controlled experiment.
The reductionist approach tends to look for simple, unitary causes to complex phenomena. We will see several examples of this when we examine the topic of Behavioral Genetics, but for the moment, consider a clear-cut genetic disorder such as sickle cell anemia. We know that a single base change in the gene for the b chain of hemoglobin results in the substitution of a valine for a glutamic acid in the protein. As a result, the hemoglobin forms long polymers in the deoxygenated state and a change in the shape of the affected individual’s red blood cells, Understanding the molecular basis of sickle cell anemia can be considered a triumph of the reductionist approach. Yet, when we take this to the next level and consider the clinical symptoms of individuals who carry this gene, we find a wide range of clinical outcomes. These can all be explained by the genetic defect, but knowing that individual has the defective gene does not tell us exactly what the state of their health will be since a number of other variables will determine the overall effect.
The Steven Rose article on neurogenetic determinism examines some of the problems in applying a reductionist approach to human behavior. Read this article carefully. Rose points to several problems, and I would like you to be able to define and give an example of each of these terms:
2. Other Readings on Reductionism
"In dispraise of reductionism" by Erwin Chargaff BioScience 47: 795-798 (1997)
Promises and Limits of Reductionism in the Biomedical Sciences (M.H.V. Van Regenmortel and D.I. Hull, eds) John Wiley and Sons (2002)