New historical and philosophical perspectives on quantitative genetics.

The aim of this virtual special issue is to bring together philosophical and historical perspectives to address long-standing issues in the interpretation, utility, and impacts of quantitative genetics methods and findings. Methodological approaches and the underlying scientific understanding of genetics and heredity have transformed since the field's inception. These advances have brought with them new philosophical issues regarding the interpretation and understanding of quantitative genetic results. The contributions in this issue demonstrate that there is still work to be done integrating old and new methodological and conceptual frameworks. In some cases, new results are interpreted using assumptions based on old concepts and methodologies that need to be explicitly recognised and updated. In other cases, new philosophical tools can be employed to synthesise historical quantitative genetics work with modern methodologies and findings. This introductory article surveys three general themes that have dominated philosophical discussion of quantitative genetics throughout history: (1) how methodologies have changed and transformed our knowledge and interpretations; (2) whether or not quantitative genetics can offer explanations relating to causation and prediction; and (3) the importance of defining the phenotypes under study. We situate the contributions in this virtual special issue within a historical framework addressing these three themes.

Digital humanism.

Much history of psychology presumes a discordance between its humanistic methods and the focus on rigorous statistical reasoning that is typical of the field it studies. However, the conditions of abundant data typical of digital humanities tend to relax the constraints of tests of significance and to allow greater freedom to try out alternative interpretations within the frame of a single study. At the same time, the elusiveness of rigorous standardization within a very large database, especially if it stretches over wide spaces or many decades, may be seen to demand meticulous source criticism of a sort that has more often been associated with the humanities than with quantitative science. There is even a tendency for the data itself to drift away from its usual function as a means of research and to become itself an object of study, inspiring reflection on how the tools and concepts of a field like psychology may be evolving in response to new constraints or ambitions. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

The curious case of blending inheritance.

For more than a century, geneticists have consistently identified the origins of their science with Gregor Mendel's experiments on peas. Mendelism, they have said, demonstrated at long last that biological inheritance was not, as had so often been supposed, "blending," but particulate. Many historians of biology continue to interpret the conflict of biometricians and Mendelians at the start of the twentieth century in these terms, identifying biometry with the (incorrect) blending mechanism. But this view of blending is history as war by other means. While Francis Galton's contrast between blended and alternate inheritance had become familiar by 1905, he and his interpreters understood the two forms as differing outcomes of breeding, not as rival theories. Only a few biologists in this period went beyond blending as a description of results of breeding to a blending mechanism, and these were not biometricians. Recognizing this, we can see also that statistical methods and models were central to evolutionary genetics right from the start. The evolutionary synthesis, while reshaping their role, did not create it.