Broadly speaking, modern animal experimentation began in seventeenth-century England and France. It has been central to our understanding of animal and human physiology ever since. A famous early example is William Harvey's investigation of the role of the heart in blood circulation. Observing the hearts of live animals with opened thoraxes, Harvey was able to see that the blood circulates in the body as a result of contractions of the heart.
In the first place, then, when the chest of a living animal is laid open and the capsule that immediately surrounds the heart is slit up or removed, the organ is seen now to move, now to be at rest; there is a time when it moves, and a time when it is motionless...We are, therefore, authorized to conclude that the heart, at the moment of its action, is at once constricted on all sides, rendered thicker in its parietes and smaller in its ventricles, and so made apt to project or expel its charge of blood.
William Harvey (1628) On the Motion of the Heart and Blood in Animals
It is difficult to imagine how discoveries such as this could have been made in Harvey's time without vivisection in its true sense — that is, without the cutting open of live animals.
More recently, experiments on animals have played a central role in the development of vaccines and therapeutic treatments for a number of infectious diseases, including anthrax, smallpox, rabies, yellow fever, typhus, and polio.1 They have been equally important in the study of noninfectious diseases, playing a part in the development of insulin in the treatment of diabetes, techniques of blood dialysis for patients with kidney failure, transplantation techniques, and advances in various types of surgery.2 And there is little doubt that, if it continues to be pursued, animal research will make important contributions to the development of new medical treatments at the initial stages of research, in the subsequent development of treatments, and in the safety testing of pharmaceutical products.
Live animal experimentation is also conducted outside the field of biomedicine. Animals are used in fundamental research in the life sciences, not only in studies pursued within a broadly biomedical perspective, but also in basic work in biology and psychology. They are also used to test new products and substances for toxicity and other possible negative effects on human health prior to marketing — although alternatives to animal use in toxicology studies are constantly being developed, and where animals are still used, refinement of the techniques has reduced the number of animals required and reduced suffering.3
We can summarize the current situation, then, by saying that most experimental animals are used for three main purposes: to develop pharmaceutical and other medical products; to advance fundamental research in the life sciences; and to test the safety of potentially toxic products and substances. These, at least, are the uses of animals on which we shall concentrate in this chapter. We readily acknowledge that animals are used in biomedicine in other ways as well: for example, in the breeding of more animals for research, the education and training of scientists and veterinary personnel, and the diagnosis of disease and the production of biological matter, such as cells and antibodies.
The proportion of experimental animals used for each of the purposes just distinguished varies from country to country. It depends on the presence and activity of biomedical research and the pharmaceutical industry in that country and, less directly, on the way "animal experimentation" is defined in the relevant legislation. According to the latest available statistics from the European Union, in 1996, most experimental animals (44%) were used in the research, development, and quality control of products for human and veterinary medicine. Fewer animals (25%*) were involved in fundamental biological research, and fewer still (9%) in toxicology and other safety testing.4
In connection with any research project falling into one of the three categories identified, we can ask: must this project involve animal experimentation? We can also ask: must this project be carried out at all? In some cases, the answer to one of these questions will be negative. It might be the case, for example, that the scientists are accustomed to proceeding in the way they currently do and are unaware of alternative methods. Similarly, regulatory bodies might continue to require animal tests that have always been applied even though there are now alternatives to using live animals as a means for research. Again, a comprehensive review of the literature may reveal that the results of an animal experiment involve duplication or are unnecessary for some other reason. To give more specific examples, it might be possible to exploit cell lines, or some other replacement method, or to use human volunteers.
Inevitably, however, there will be many cases in which it is essential to study an intact, living organism and in which the procedure or substance is too risky or too invasive to permit human volunteers to be used. In these cases especially, we need to consider carefully what costs we are imposing on the relevant animals.
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