The History of Animal Experimentation

Vivisection—the cutting open of living animals to observe their inner structure and functioning—can be traced to Greek antiquity, but it was Galen (129—c. 210 c.e.), the most celebrated physician of the Roman Empire, who developed vivisection as a tool for methodical physiological investigation. By such procedures as ligation of the ureters to show they channeled urine from the kidneys to the bladder, and sectioning of the spinal cord at different levels to establish the relations between individual nerves and the body regions they served, Galen demonstrated the power of surgical interventions to produce a deeper understanding of bodily functions (Rupke).

During the early medieval period, animal experimentation fell into the same desuetude as other areas of scientific inquiry. To be sure, ancient scientific traditions were preserved and elaborated upon by Arabic scholars, but not until the late Middle Ages did an experimental spirit revive in the European world. Skepticism about the adequacy of ancient scientific ideas built to a head during the 1500s, culminating for the life sciences in the 1543 publication of De Humani Corporis Fabrica by Andreas Vesalius (1514-1564). The first anatomy text based on careful dissection of the human body, Vesalius's work sharply revised the long-accepted anatomical system of Galen (which had been derived entirely from animal dissections), and thus encouraged experimental reevaluation of Galenic theories of physiology as well.

The most significant correction of Galen's physiology was accomplished by the English physician William Harvey (1578-1657), whose demonstration of the circulatory movement of the blood through the body was based on observations of the contractions of the heart, ligation of the aorta and vena cava, and other vivisection procedures performed on more than eighty species. Harvey's De Motu Cordis (1628) heightened misgivings about the validity of other Galenic ideas and confirmed animal experimentation as an invaluable technique for physiological discovery. Vivisection became a commonplace scientific activity by the later 1600s; it was used over the next century and a half to investigate such varied phenomena as respiration, pancreatic secretion, and blood pressure (Rupke; Foster).

Yet as late as 1800, experimentation was still only one of several approaches to elucidating physiological processes. Drawing conclusions about function on the basis of structure—deducing physiology from anatomy—remained popular, as did a priori theorizing in accord with some physical or chemical model; experimentation might be employed in either of those cases, but only to substantiate the preestablished theory. That overly rationalistic orientation to physiology and medicine was already coming under attack, however, by the philosophe-physicians of the "Paris School." Their call for a medicine rooted in empiricism was answered most eagerly and effectively by Francois Magendie (1783-1855), who from 1805 through the 1820s used animal experimentation to clarify such questions as the mode of action of strychnine, the mechanism of emesis, and the functioning of the nervous system. Magendie insisted on analyzing function without being prejudiced by anatomical structure, and thereby established irrevocably the superiority of the experimental method for physiological inquiry. (Contemporaneously, researchers at French veterinary schools were also developing physiology along experimental instead of speculative lines). Magendie's pupil, Claude Bernard (1813-1878), utilized the experimental method even more successfully, discovering the vasomotor nerves, the glycogenic activity of the liver, the digestive role of pancreatic juice, and the mechanism of curare's effects on neuromuscular function. Bernard was equally significant for the philosophical analysis of the necessity of animal experimentation presented in his Introduction a I'etude de la medecine experimental^ (1865). There he argued that it was unethical to experiment on human beings, no matter how beneficial the findings might prove for others, if the experiment could harm the subject to any extent whatever. Benefit to others did, on the other hand, justify experiments, including painful ones, on animals. The fact that many human lives could be saved by a relatively few animal deaths made the practice of vivisection a "right," he concluded, "entirely and absolutely" (p. 178). Bernard's analysis solidified the recognition of experimental research with animals as an essential practice for medical progress (Lesch; Rupke; Schiller).

At the same time, physiology and other experimental medical sciences were achieving the status of distinct, institutionalized professions. Historically, physiology had been pursued by physicians in whatever time they had left from treating patients or giving university lectures (and also, on occasion, by amateurs of means). The French had taken the lead in making physiology an independent discipline, yet it was in Germany that research physiology bloomed as a new professional field. The nineteenth-century reformation of universities in the German states, with its emphasis on research and the uncovering of new knowledge, led to the establishment of research institutes employing full-time physiologists, along with pharmacologists and other biological experimenters (Coleman and Holmes). The expectation that research would result in practical medical applications useful to humankind attracted both political and philanthropic support, and ultimately expectation was fulfilled with the flowering of medical microbiology and immunology in the 1880s. The germ theory was built upon laboratory experiments on thousands of animals; applications of the theory quickly made surgery far more effective and safe, and sharply refined programs for the prevention of epidemic disease. Louis Pasteur (1822-1895) discovered a vaccine for rabies in 1885 by infecting numerous dogs and rabbits with the disease, while the research leading to the introduction of diphtheria antitoxin in 1891 involved injecting guinea pigs, rats, and other species with diphtheria toxin. Such breakthroughs allowed experimental medicine to grow by feeding on itself, discovery generating support for more laboratories and scientists, leading to further discovery. By 1900, the German research ethos had established itself throughout the Western hemisphere, even in the United States (Fye). During the course of the twentieth century, moreover, the use of animals in research spread beyond the boundaries of physiology and pharmacology into areas such as psychology, the standardization of drug products, and toxicity testing of cosmetics and other consumer products. The "laboratory animal" has become a universal tool and symbol of medical progress and modern civilization.

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