8 Nov 2018
Ute Deichmann
Jacques Loeb Centre for the History and Philosophy of the Life Sciences
Ben-Gurion University of the Negev, Israel
The concepts of biological specificity (of species, macromolecules, genes etc.) and genetic causality (in particular regarding heredity and development) played an important role in rendering biology a modern experimental science in the nineteenth century. Neglecting these concepts often led to stagnation in a field of study as, for example, in Spemann's embryology, which excluded genetic causality.
Mathematical models, which were widespread in experimental biology since its beginnings, differed, among other things, in the consideration of these principles. This paper presents the properties and epistemological basis of pertinent models, from Mendel's model of heredity in the 19th century to Eric Davidson's model of developmental gene regulatory networks in the 21st, and analyzes the extent to which the above principles explicitly or implicitly guided the modelling process. It claims that models that disregarded these principles, such as D'Arcy Thompson's models of biological form, failed to impact the direction of biological research in a lasting way. The paper shows that a combination of theory and mathematical modelling with experiment has led to the most fruitful concepts in the history of biology, such as the DNA double helix and the genetic code. The history of mathematical modelling shows, moreover, that the ideal of simplicity that is widely accepted in physics and sometimes fruitful also in biology, can be strongly misleading if taken alone, because biological entities and processes are the result of a long evolutionary history.