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Brauckmann Sabine | Fellow Postdoctoral
2003-05-01 - 2005-04-30 | Research area: History of Biology
Fields, Graphs, and Sets: A Treatise on Theoretical Biology (1910-1960)
The project will reconstruct three holistic models formulated from 1910 to 1960. These models aimed to apply the language of mathematics to biology in order to describe adequately such complex processes as development and evolution. These theories shared the objective to solve the crucial issue of how an egg cell, as if guided by a magic hand, is transformed into an outgrown organism. The quest for the agent writing the choreography of this cellular ballet is the point of departure of Gurwitsch's field theory, Rashevsky's biological graphs, and Elsasser's theory of finite classes. For example, based on conchoidal patterns, the field model applies stochastic reasoning to construe the phenomenon of embryogenesis without reducing the organic form to the molecular structure of the nucleus. Due to the field factor, a holistic network is induced that controls the geometric relations between neighboring cells over the course of morphogenesis. Finally, the gestalt is configured by random walks of the field parameters along cell membranes. First approaches to connect the statistical field of cell movements with the experimental issue of the chemical organizer were formulated independently from each other by Holtfreter (cell adhesion hypothesis) and Waddington (epigenetic landscape). The essential difference between the latter and the European field model is that Waddington interpreted the field agent in terms of a biochemical attractor, later relabelled chreod, which folds up the genetic program of development. The advantage of the field theory in general was that biology could now study pattern formation as a virtual shift of trajectories. According to holistic approaches, ontogenetic processes can be analyzed because they are observable in principle; they can be measured and formally described in a coarse grid due to the finite number of particles. If, however, the developmental fate of a single cell should be determined, the simulation must include the moving boundaries of cell membranes as the chemical and physical gradients of the cellular inside. These models did not achieve this yet. The project will study in detail whether the computer as a new experimental tool fulfills the demand. The cell, formerly thought of as a simple atom of life, turned out to be one of the world’s most complex factories, as Weiss already stated in the 1950s. Therefore, whether organic form as resulting from an evolutionary fixed bauplan — folded inside the genetic code of the zygote — and the mathematical model will be congruent to each other, is still in dispute.