Over the past century, our bodies have increasingly become exposed to the pharmaceutical action of incorporated biological substances. Some of these have become so ubiquitous that we have even stopped thinking about them as ‘biologics’. We swallow our daily vitamin pills; we rely on vaccines and antibiotics when microbes proliferate; we account for the adverse effects of cortisone; we live a more-or-less normal life thanks to regular injections of insulin or an organ transplant; and we place our faith in monoclonal antibodies when a tumour has been diagnosed. One recent textbook definition of biologics provides us with still more examples:

This recent definition does not include vitamins, hormones, antibiotics or vaccines, although they have been and sometimes still are categorized as ‘biologics’ or ‘biologicals’.

The term ‘biologics’ first emerged in connection with national health-care legislation and the control of vaccine production in the US more than a hundred years ago.

History of science and science studies have become increasingly interested in models and modelling processes in recent years. One reason for this is the awareness that the understanding of experimental science begins with the understanding of experimental practice. As scholars have long recognized, reasoning through experimental animals became the lingua franca of biologists entering the twentieth century, and the choice of organism has proven critical to scientific development. From an epistemological point of view, this kind of reasoning is far more complex than it may seem at first glance. This is because animals are not the only ‘ingredient’ needed in modelling: ‘Model organisms can be seen as a specialized subset of the more general class of model systems, where the latter usually encompassed not only the organism but also the techniques and experimental methodologies surrounding the organism’.

Historically speaking, the mode and experimental arrangement of models has changed significantly since the emergence of organized experimental biology. Cheryl Logan has described how nineteenth-century rationales for the choice of test organisms in physiology were transformed after 1900. This change was driven by various developments in biological thought and theory, the requirements of the experimental method and new technologies of experimentation. As a consequence of the formation of Mendelian genetics, geneticists and physicians alike sought to contribute experimentally to the understanding of human heredity with respect to medical problems.