Matteo Mameli

Cultural traits are those phenotypic traits whose development depends on social learning. These include practices, skills, beliefs, desires, values, and artefacts. The distribution of cultural traits in the human species changes over time. But this is not enough to show that culture evolves. That depends on the mechanisms of change. In the cultural realm, one can often observe something similar to biology’s ‘descent with modification’: cultural traits are sometimes modified, their modifications are sometimes retained and passed on to others through social learning, until new modifications are added. In this way, new modifications are piled on top of old modifications, generating cumulative change. But, again, this is not enough to show that culture evolves. For culture to evolve, cumulative change must be the result of hidden-hand mechanisms similar to those that explain cumulative biological change. If cumulative cultural change cannot be explained in these terms, the analogy between cultural change and biological evolution is unhelpful. The best known biological mechanism is natural selection. There are reasons to think that cultural change is at least sometimes due to natural-selection-like mechanisms. The adaptive fit often found between cultural traits and the environment has in many cases been built gradually and in a way that involves natural selection operating at the cultural level. The parallel with morphological adaptation is compelling. No complete and universally accepted account of natural-selectionlike processes operating at the cultural level exists at this stage. But at least three kinds of processes seem possible.

A recent study by Castellani et al. (JAMA 302(23):2573–2579, 2009) describes the population-level effects of the choices of individuals who underwent molecular carrier screening for cystic fibrosis (CF) in Veneto, in the northeastern part of Italy, between 1993 and 2007. We discuss some of the ethical issues raised by the policies and individual choices that are the subject of this study. In particular, (1) we discuss the ethical issues raised by the acquisition of genetic information through antenatal carrier testing; (2) we consider whether by choosing to procreate naturally these couples can harm the resulting child and/or other members of society, and what the moral implications of such harm would be; (3) we consider whether by choosing to avoid natural procreation carrier couples can harm current or future individuals affected by cystic fibrosis; (4) we discuss whether programs that make carrier testing available can be considered eugenic programs.

I present and apply some powerful tools for studying human evolution and the impact of cultural resources on it. The tools in question are a theory of niche construction and a theory about the evolutionary significance of extragenetic (and, in particular, of psychological and social) inheritance. These tools are used to show how culturally transmitted resources can be recruited by development and become generatively entrenched. The case study is constituted by those culturally transmitted items that social psychologists call ‘expectancies’. Expectancy effects are mindshaping effects of our mindreading dispositions. I show how expectancies may have been recruited by important human developmental processes (like those involved in language acquisition and those responsible for gender differences) and how they may have become entrenched. If the hypothesis is correct, the relation between mindreading and human evolution is more intricate than usually thought

Since the discovery of the double helical structure of DNA, the standard account of the inheritance of features has been in terms of DNA-copying and DNA-transmission. This theory is just a version of the old theory according to which the inheritance of features is explained by the transfer at conception of some developmentally privileged material from parents to offspring. This paper does the following things: (1) it explains what the inheritance of features is; (2) it explains how the DNA-centric theory emerged; (3) it clarifies the relation between the DNA-centric theory and the ‘unfolding’ theory of development; (4) it argues that (given what we now know about developmental processes and genetic activity) the DNA-centric theory should be abandoned in favour of a pluralistic (but not holistic) theory of the inheritance of features. According to this pluralistic theory, the reliable reoccurrence of phenotypes must be explained by appealing not only to processes responsible for the reliable reoccurrence of genetic developmental factors but also to processes responsible for the reliable reoccurrence (or persistence) of nongenetic developmental factors.