Gluing life together. Computer simulation in the life sciences: an introduction.

Over the course of the last three decades, computer simulations have become a major tool of doing science and engaging with the world, not least in an effort to predict and intervene in a future to come. Born in the context of the Second World War and the discipline of physics, simulations have long spread into most diverse fields of enquiry and technological application. This paper introduces a topical collection focussing on simulations in the life sciences. Echoing the current state of tinkering, fast developments, segmentation of knowledge and interdisciplinary collaboration, and in an effort to bridge the science-humanities divide, the contributors to this collection come from multiple disciplinary backgrounds, including information studies, cognitive sciences, philosophy and biology. The ambiguous character of simulations, their cutting across scientific disciplines, analysis and prediction, understanding and doing, gave rise to their success in contemporary life sciences and has been the object of much scientific debate. One of the main aims of this topical collection, by contrast, is to call into question the assumption of an obvious use and easy transfer of methods between fields of knowledge as diverse as, e.g. physics and biology. The collection presents historical case studies from various biological sub-fields. The articles study how simulations are used and the ways they contribute specifically to our understanding of life. Taking up Sergio Sismondo's description of simulations as "compromises" and "glue", they also critically engage with the question of what exactly the life sciences have been gluing together over the last two decades.

Model and movement: studying cell movement in early morphogenesis, 1900 to the present.

Morphogenesis is one of the fundamental processes of developing life. Gastrulation, especially, marks a period of major translocations and bustling rearrangements of cells that give rise to the three germ layers. It was also one of the earliest fields in biology where cell movement and behaviour in living specimens were investigated. This article examines scientific attempts to understand gastrulation from the point of view of cells in motion. It argues that the study of morphogenesis in the twentieth century faced a major dilemma, both epistemological and pictorial: representing form and understanding movement are mutually exclusive, as are understanding form and representing movement. The article follows various ways of modelling, imaging, and simulating gastrular processes, from the early twentieth century to present-day systems biology. The first section examines the tactile modelling of shape changes, the second cell cinematography, mainly the pioneering work of the German embryologists Friedrich Kopsch and Ernst Ludwig Gräper in the 1920s but also a series of classic, yet not widely known, studies of the 1960s. The third section deals with the changes that computer simulation and live-cell imaging introduced to the modelling of shape change and the study of cell movement at the turn of the twenty-first century. Although live-cell imaging promises to experiment upon and represent the living body simultaneously, I argue that the new visuals are an obstacle rather than a solution to the puzzle of understanding cell motion.

Animating embryos: the in toto representation of life.

With the recent advent of systems biology, developmental biology is taking a new turn. Attempts to create a 'digital embryo' are prominent among systems approaches. At the heart of these systems-based endeavours, variously described as 'in vivo imaging', 'live imaging' or 'in toto representation', are visualization techniques that allow researchers to image whole, live embryos at cellular resolution over time. Ultimately, the aim of the visualizations is to build a computer model of embryogenesis. This article examines the role of such visualization techniques in the building of a computational model, focusing, in particular, on the cinematographic character of these representations. It asks how the animated representation of development may change the biological understanding of embryogenesis. By situating the animations of the digital embryo within the iconography of developmental biology, it brings to light the inextricably entwined, yet shifting, borders between the animated, the living and the computational.

Folding into being: early embryology and the epistemology of rhythm.

Historians have often described embryology and concepts of development in the period around 1800 in terms of "temporalization" or "dynamization". This paper, in contrast, argues that a central epistemological category in the period was "rhythm", which played a major role in the establishment of the emerging discipline of biology. I show that Caspar Friedrich Wolff's epigenetic theory of development was based on a rhythmical notion, namely the hypothesis that organic development occurs as a series of ordered rhythmical repetitions and variations. Presenting Christian Heinrich Pander's and Karl Ernst von Baer's theory of germ layers, I argue that Pander and Baer regarded folding as an organizing principle of ontogenesis, and that the principle's explanatory power stems from their understanding of folding as a rhythmical figuration. In a brief discussion of the notion of rhythm in contemporary music theory, I identify an underlying physiological epistemology in the new musical concept of rhythm around 1800. The paper closes with a more general discussion of the relationship between the rhythmic episteme, conceptions of life, and aesthetic theory at the end of the eighteenth century.

[Picture metamorphosis. The transformation of insects from the end of the seventeenth to the beginning of the nineteenth century]. / Die Metamorphose der Bilder. Die verwandlung der Insekten und ihre Darstellung vom Ende des 17. bis zum Anfang des 19. Jahrhunderts.

The paper discusses the history of research into the problem of insect metamorphosis from the middle of the seventeenth century to the beginning of the nineteenth century. In particular, the work of three central figures is discussed: Jan Swammerdam (1637-1680), Pierre Lyonet (1706-1789) and Johann Moritz David Herold (1790-1862). It is argued that an understanding of the history of the problem of metamorphosis requires a careful analysis of its pictorial dimension. For Swammerdam, the central aim was a visualisation of the mechanical process by which, as he assumed, the butterfly is enfolding out of the larva. Lyonet's aim was a schematic representation of the structure of the organs, layer by layer, in order to understand the inner changes that the organs are undergoing throughout metamorphosis. Herold, working in the context of epigenetic embryology, took a very different strategy: the developmental series became the central pictorial means by which development as a gradual process of transformation was depicted.