Human beings are a marvel of evolved complexity. Such systems can be difficult to enhance. When we manipulate complex evolved systems, which are poorly understood, our interventions often fail or backfire. It can appear as if there is a “wisdom of nature” which we ignore at our peril. Sometimes the belief in nature’s wisdom—and corresponding doubts about the prudence of tampering with nature, especially human nature—manifests as diffusely moral objections against enhancement. Such objections may be expressed as intuitions about the (...) superiority of the natural or the troublesomeness of hubris or as an evaluative bias in favor of the status quo. This chapter explores the extent to which such prudence-derived anti-enhancement sentiments are justified. We develop a heuristic, inspired by the field of evolutionary medicine, for identifying promising human enhancement interventions. The heuristic incorporates the grains of truth contained in “nature knows best” attitudes while providing criteria for the special cases where we have reason to believe that it is feasible for us to improve on nature. (shrink)

This paper attempts to debunk the slippery-slope argument against human germ-line gene therapy by showing that the downside of the slope – genetic enhancement – need not be as unethical or unjust as some people have supposed. It argues that if genetic enhancement is governed by proper regulations and is accompanied by adequate education, then it need not violate recognized principles of morality or social justice. Keywords: germ-line therapy, slippery slope argument, future generations, social justice CiteULike Connotea Del.icio.us What's this?

Any suggestion of altering the genetic makeup of human beings through gene therapy is quite likely to provoke a response involving some reference to a 'slippery slope'. In this article the author examines the topography of two different types of slippery slope argument, the logical slippery slope and the rhetorical slippery slope argument. The logical form of the argument suggests that if we permit somatic cell gene therapy then we are committed to accepting germ line gene therapy in the future (...) because there is no logically sustainable distinction between them. The rhetorical form posits that allowing somatic cell therapy now will be taking the first step on a slippery slope which will ultimately lead to the type of genocide perpetrated by the Nazis. The author tests the validity of these lines of argument against the facts of human gene therapy and concludes that because of their dependence on probabilities that cannot be empirically proven they should be largely disregarded in the much more important debate on moral line-drawing in gene therapy. (shrink)

Gene therapy is still a very crude way of treating very complicated problems. It's hard to get new genes to go where they're needed, and hard to keep them from going where they're not wanted. The worst‐case scenario is that they find their way into a patient's germ cells—eggs or sperm—and end up harming the patient's offspring. Yet this possibility is hard to study in human trials, and would be hard to deal with in the clinic. It should, instead, simply (...) be avoided. Doing so requires fundamentally changing our approach to gene therapy. (shrink)

This paper elaborates the hypothesis that the unique demography and sociology of Ashkenazim in medieval Europe selected for intelligence. Ashkenazi literacy, economic specialization, and closure to inward gene flow led to a social environment in which there was high fitness payoff to intelligence, specifically verbal and mathematical intelligence but not spatial ability. As with any regime of strong directional selection on a quantitative trait, genetic variants that were otherwise fitness reducing rose in frequency. In particular we propose that the well-known (...) clusters of Ashkenazi genetic diseases, the sphingolipid cluster and the DNA repair cluster in particular, increase intelligence in heterozygotes. Other Ashkenazi disorders are known to increase intelligence. Although these disorders have been attributed to a bottleneck in Ashkenazi history and consequent genetic drift, there is no evidence of any bottleneck. Gene frequencies at a large number of autosomal loci show that if there was a bottleneck then subsequent gene flow from Europeans must have been very large, obliterating the effects of any bottleneck. The clustering of the disorders in only a few pathways and the presence at elevated frequency of more than one deleterious allele at many of them could not have been produced by drift. Instead these are signatures of strong and recent natural selection. (shrink)