Passage Six

The use of animals to better understand human anatomy and human disease is a centuries-old practice. Animal research has provided valuable information about many physiological processes that are relevant to humans and has been fundamental in the development of many drugs, including vaccines, anesthetics, and antibiotics. Animals and humans are similar in many ways. Animal behavior can be as complex as human behavior, and the cellular structures, proteins, and genes of humans and animals are so similar that the prospect of using animal tissues to replace diseased human tissues is under intense investigation for patients who would otherwise never receive a potentially life-saving transplant.

However, the way in which animals and humans react to their environments, both physiologically and behaviorally, can be drastically different, and the conditions under which laboratory animals are kept can influence and alter experimental results. The husbandry and treatment of laboratory animals has been and continues to be a major topic of ethical debate. Concern over the care and management of animals used in scientific research was initially raised in the 19th century in Great Britain, where the Cruelty to Animals Act was adopted in 1876. A significant step forward — for both supporters and opponents of animal research — occurred in 1959, when British zoologist William Russell and British microbiologist Rex Burch published The Principles of Humane Experimental Technique. This work introduced the goals of replacement, reduction, and refinement: replacement of animal testing with other techniques, reduction of the number of animals tested, and refinement of animal tests to reduce suffering. These concepts became the foundation for the development of scientific alternatives to animal testing, and they continue to guide the treatment of animals in modern scientific research.

Alternatives to animal testing are primarily based on biochemical assays, on experiments in cells that are carried out in vitro (“within the glass”), and on computational models and algorithms（演算法）. These techniques are typically far more sophisticated and specific than traditional approaches to testing in whole animals, and many in vitro tests are capable of producing information about the biological effects of a test compound that are as accurate — and in some cases more accurate than — information collected from studies in whole animal.

Traditional toxicity tests performed on animals are becoming outmoded. These tests result in the deaths of many animals and often produce data that are irrelevant to humans. Recognition of the inadequacy of animal toxicity testing has resulted in the development of better techniques that are able to produce comparable toxicity values of chemicals that are applicable to humans.

While animal testing is not always the most efficient way to test the toxicity of a chemical or the efficacy of a pharmaceutical compound, it is sometimes the only way to obtain information about how a substance behaves in a whole organism, especially in the case of pharmaceutical compounds. Studies of pharmacokinetic effects (effects of the body on a drug) and pharmacodynamic effects (effects of a drug on the body) often require testing in animals to determine the most effective way to administer a drug; the drug’s distribution, metabolism, and excretion; or any side effects in the body. These studies are dependent on a circulating system, which are extraordinarily difficult to perform outside animal bodies, since in vitro studies often cannot form a complete picture of a drug’s action.

Supporters and opponents of animal testing sometimes have the same goals; however, an extraordinary amount of energy is wasted both on poorly executed animal testing and on poorly conceived efforts to stop animal testing. Because of the enormous effort required to change decades of research and product development that has crucially depended on animal testing, the unification of organizations that bring together supporters of animal welfare and supporters of science is required. This unification is taking place, and interest in and support for these organizations is growing.

Why are animal researches so important in medical experimentations?

From the second paragraph, what topic is raised for discussion?

Which of the following is NOT the reason that the opponents of the animal research base their view?

Why is animal testing irreplaceable in some cases?

What message does the author try to convey about the scientific experimentation in animals?