In this blog post, I will examine the role animal experiments have played in the advancement of biotechnology and medical technology, and consider whether it is necessary to continue animal experiments while taking into account animal rights and ethical issues.
Following the eras of mechanical and chemical engineering, biotechnology is advancing at a rapid pace. Biotechnology has established itself as a vital field for humanity by contributing to the extension of human lifespan and the treatment of various diseases. However, this often involves repetitive animal testing and clinical trials, and controversy surrounding animal testing continues throughout this process. Despite the ongoing controversy, animal testing is still being conducted, and its necessity is difficult to ignore. However, there has recently been a growing movement to utilize alternative testing methods—such as cell- and tissue-based experiments, organoids, organ-on-a-chip technologies, and computer modeling—rather than assuming animal testing is an absolute prerequisite. Therefore, I intend to argue for its necessity, focusing on why animal testing is needed and under what circumstances it should be restricted.
The history of animal experimentation dates back to ancient animal dissection and in vivo observation, and modern physiological animal experimentation saw significant development in the 19th century. In particular, the 19th-century French physiologist Claude Bernard emphasized experimentation as a crucial method for physiological research and sought to elucidate biological phenomena through animal testing. At that time, there was a strong view that animal testing took precedence over observations of humans, and there was also the perspective that the effects of drugs or toxic substances did not differ significantly between humans and animals. To realize the experimental physiology he pursued, Bernard prioritized the acquisition of scientific knowledge over the suffering of animals. Against this historical backdrop, some scientists viewed animals as beings inferior to humans. While awareness of animal welfare and rights has greatly increased today, the vast history of animal experimentation cannot be viewed simply as a selfish act of slaughter by humans.
First, the advancements in medical technology resulting from animal experimentation cannot be ignored. Animal experimentation has played a crucial role in accumulating medical knowledge and developing new treatments, leading to significant progress in biotechnology and medical technology. For example, as medical achievements in preventing or treating diseases fatal to human survival—such as polio, tuberculosis, rubella, and measles—have accumulated, it has become possible to reduce human suffering. In the late 19th century, Louis Pasteur used sheep to study the principles of vaccination against anthrax, making a significant contribution to the history of vaccine development. Ivan Pavlov studied classical conditioning through experiments with dogs, which contributed to the advancement of physiology and behavioral research. Furthermore, in 1921, Frederick Banting and Charles Best studied the relationship between pancreatic function and insulin through experiments on dogs, which subsequently led to the discovery of insulin and advances in the treatment of diabetes. These studies helped resolve issues directly linked to human well-being and played a crucial role in extending human life expectancy and reducing anxiety about disease.
Next, animal testing plays a crucial role in the pharmaceutical sector, particularly in the development of new drugs. Since new drugs are newly developed substances, research begins when there is insufficient information regarding their safety and mechanisms of action. The purpose of developing new drugs is to treat human diseases and alleviate symptoms. However, unexpected side effects may arise as the drug acts on the human body, and it is necessary to identify these risks as thoroughly as possible before administering the drug to humans. Of course, today’s drug development also utilizes various non-animal testing methods, such as tests using cells and tissues and computer-based predictions, and clinical trials are conducted in accordance with strict ethical standards and procedures. However, there are limitations to identifying all potential side effects in advance through clinical trials alone. In particular, early-stage clinical trials are conducted with a limited number of participants, and there are ethical and practical constraints on the scope of testing that can be performed directly on humans to ensure safety. Therefore, preclinical studies are necessary to assess a drug’s toxicity and pharmacological effects prior to human clinical trials, and animal testing is still utilized in this process today. Furthermore, one advantage of animal testing is that humans and animals share certain similarities in their nervous systems and organs, allowing researchers to observe how a drug affects living organisms. Another advantage is the ability to adjust the sample size according to the purpose of the experiment and to control the influence of external factors by maintaining a consistent environment. For these reasons, conducting repeated animal experiments to identify symptoms of side effects or the efficacy of a drug can help advance medical technology while minimizing risks before testing on humans. However, there has recently been a shift toward using animal testing only when absolutely necessary and actively utilizing reliable alternative testing methods when available.
In response to such arguments, some might contend that even though animal testing has contributed significantly to medical technology, since only 1.16% of diseases are shared between humans and animals, it is difficult to directly apply the results obtained from animal testing to humans, and therefore, its practical effectiveness is limited. Although this 1.16% figure has long been cited as evidence of the limitations of animal testing, it is not sufficient to judge the validity of all animal testing based solely on this single statistic.
However, even if diseases are not completely shared, it is possible to conduct experiments to verify the responses of organs or the nervous system, and the physiological and pharmacological information obtained from animals is also meaningful in the process of developing drugs applicable to humans. In particular, experimental results obtained from animals that are genetically and biologically relatively similar to humans can be used to understand the effects and toxicity of specific drugs. Preclinical research, including animal testing, has played a crucial role in various medical fields, such as vaccines, antibiotics, anesthetics, insulin, cancer treatment, heart disease treatment, surgical procedures, and organ transplants. However, it is inappropriate to attribute all these medical achievements solely to animal testing; one must also consider that they resulted from a combination of various research methods, including cellular and clinical studies. In particular, experiments using dogs played a crucial role in the discovery of insulin, and the research conducted by Banting and Best in 1921 brought about a revolutionary change in the treatment of diabetes. Therefore, while it is difficult to deny that animal testing has made a certain contribution to the advancement of modern medicine, this contribution alone cannot justify all animal testing.
Others may question whether humans are superior to animals and argue that animals, too, are beings that coexist in nature and deserve moral consideration equal to that of humans. Consequently, while animals do have the right to life and to live autonomously, it can be argued that animal experiments should no longer be conducted because some involve cruel methods that induce convulsions or seizures in animals and leave them with irreversible damage—such as death or physical deformities—after the experiments.
First, while I believe there are cases where human welfare holds greater value than animal dignity, this does not mean I view animal life as worthless. Animals, too, are beings that must coexist with humans on Earth. Therefore, I believe cruel experiments—where the results are already sufficiently predictable or where the scientific or societal necessity is low—should be restricted or banned. In the early days of animal experimentation, experiments often involved inflicting direct physical harm on animals to determine the specific effects of certain drugs on organs such as the cornea or the inner lining of the stomach. However, as medical technology has advanced and a wealth of anatomical and physiological knowledge has been accumulated, the need to reduce experiments that cause direct physical harm to animals—merely to repeatedly verify past findings—has become even more urgent. It is preferable to utilize existing knowledge and conduct ethical experiments that are reproducible while minimizing the suffering inflicted on animals.
Furthermore, South Korea has established a regulatory framework governing the use of laboratory animals and animal experimentation. According to the 2024 survey conducted by the Animal and Plant Quarantine Agency, a total of 4,592,958 animals were used in experiments during 2024, of which rodents accounted for 4,067,518, or 88.6%. Mice accounted for the largest number at 3,744,411, followed by rats at 268,600. Therefore, considering that most animals used in experiments are rodents such as mice and rats, it is important to systematically manage their breeding and supply during the rearing and care process and to reduce indiscriminate animal experimentation in accordance with the 3R principles. It is also worth noting that in 2024, 2,364,100 animals—accounting for 51.5% of the total—were used in experiments classified as Grade E, the highest level of suffering. This demonstrates that efforts to reduce suffering and replace unnecessary experiments are more important than simply continuing animal testing.
Moreover, since humans are heterotrophs, we are beings that have no choice but to utilize other living organisms for survival. If we view medical technology as an extension of activities aimed at prolonging human survival and health, I believe that conducting animal testing within certain limits to protect human life and health can be justified. However, since the purposes and methods of using animals for food production differ from those of using them for scientific research, it is difficult to compare them using the same criteria. What is important is to consider, in conjunction, whether the benefit to humans is clear, whether there are no alternative methods, and whether the suffering inflicted on animals can be minimized. Therefore, it is difficult to consider it a sufficient argument to simply conclude that killing animals for food is acceptable while using animals for experiments is unconditionally unethical; conversely, one cannot justify all animal testing solely on the grounds that it benefits humans.
Second, I would like to introduce the 3R principles to those who oppose cruel animal experimentation. William Russell (W. M. S. Russell) and Rex Burch (R. L. Burch) proposed the 3Rs—Reduction, Replacement, and Refinement—as principles that researchers must follow when conducting animal experiments. Reduction in the number of laboratory animals means minimizing unnecessary or excessive use of animals and improving research design to use only the minimum number of animals necessary, while replacement of laboratory animals refers to substituting animal testing with non-animal methods such as cell culture, tissue models, or computer-based methods. Examples include efforts to replace the Draize test—in which raw materials such as cosmetics are instilled into the eyes of live rabbits to assess irritation—with alternative testing methods, as well as methods utilizing bovine eye tissue obtained during slaughter. Refinement of animal testing refers to improving experimental procedures and environments to minimize unnecessary pain and stress and to ensure the welfare and health of animals to the greatest extent possible. This principle continues to serve as an important standard for animal testing ethics today. South Korea also enacted the Animal Protection Act in 1991 and, in 2008, enacted the Act on Laboratory Animals, thereby establishing a legal framework for the ethical use of laboratory animals and the management of animal testing facilities. Therefore, conducting animal experiments in compliance with the 3R principles and relevant laws will help reduce indiscriminate testing and more actively protect animal welfare.
However, there are some animal experiments that are difficult to replace solely with experiments using non-living materials or tissue culture experiments. In mechanism-based research for the treatment of various diseases, it is sometimes necessary to induce and treat diseases using pathogens or to examine how various organs and physiological responses influence one another. Such research faces the limitation that experiments involving the culture of a single cell or tissue alone cannot fully capture the complex reactions occurring throughout an entire organ. Therefore, completely replacing all animal testing solely on the grounds of animal ethics could hinder the advancement of medical technology and may reduce opportunities to save human lives through medical innovation. Furthermore, the costs and time required to develop and validate new alternative testing methods cannot be ignored. However, new testing methods more directly relevant to humans—such as organoids, organ-on-a-chip technologies, and computer simulations—have been rapidly advancing recently. The U.S. Food and Drug Administration (FDA) is also reviewing these new approaches in the drug development process and expanding its policies toward reducing or replacing animal testing. Therefore, rather than choosing between unconditionally maintaining or immediately abolishing animal testing, we need to move toward reducing animal testing in areas where alternatives exist and applying strict ethical standards in areas where alternatives are not available.
Animal testing has long played a crucial role in human welfare, the advancement of medical technology, and the process of new drug development. The primary concerns raised by those who hold negative views on animal testing revolve around animal rights and ethics. However, rather than banning all animal testing simply because animal lives are important, we need to adhere to the 3R principles and continuously improve experimental methods while recognizing that animals are beings meant to coexist with humans. At the same time, we must acknowledge the scientific limitations of animal testing, and if alternative testing methods more suitable for humans are developed and validated, we should actively utilize them. Ultimately, acknowledging the necessity of animal testing does not mean unconditionally permitting all such experiments. Rather, it means we must pursue both the advancement of medical technology and the ethical protection of animals by constantly evaluating whether a particular experiment is truly necessary for human life and health, whether it can be replaced by other methods, and whether the suffering inflicted on the animals can be minimized.
