In this blog post, we will examine various arguments regarding the necessity and ethics of animal experiments and reflect together on their significance from today’s scientific and ethical perspectives.
The History of Animal Testing and Raised Concerns
The earliest known instance of animal testing is believed to be the in vivo dissections performed by the ancient Roman anatomist Galen, and for over 2,000 years, animal testing has provided humanity with a wealth of medical and scientific knowledge. Prominent scholars such as Hippocrates, Aristotle, and Pasteur advanced science through animal experimentation, greatly expanding our understanding of the physical structure, cells, tissues, organs, and diseases of animals, including humans. However, today there are persistent arguments that animal experimentation is not only unnecessary but also unethical. Therefore, we will examine these arguments and assess their validity.
Arguments and Limitations of the Opposition to Animal Testing
Prominent books opposing animal testing include ‘Animal Testing: Greed and Arrogance’ and ‘Science in Disguise: Animal Testing’, written by Ray Greig and Jean Swingle Greig. These works consistently highlight the adverse effects and unnecessary nature of animal testing. However, upon examining their arguments and evidence, one gets the impression that they are denying the overall usefulness of animal testing based on a few exceptional cases.
In Chapter 3, “Legislated Irrationality,” of ‘Animal Testing: Greed and Arrogance’, the authors argue that humans and animals are fundamentally different and that animal testing is conducted as a means to justify existing ways of thinking. Furthermore, in Chapter 1, “Philosophy of Science,” of ‘Animal Experimentation: Science in Disguise’, the authors argue that animal experimentation is supported solely because livestock producers, media outlets, and pharmaceutical companies derive economic benefits from it, and that it actually lacks scientific basis.
The authors explain that livestock farmers reap enormous profits from the sale of laboratory animals such as mice; the media boosts interest and revenue by exaggerating the efficacy of new drugs and downplaying their side effects; and pharmaceutical companies evade responsibility by claiming safety based on the results of animal testing.
However, it is a stretch to claim that animal testing is conducted solely for these reasons. First, it is true that animal breeders derive economic benefits from the sale of laboratory animals. However, this is merely a byproduct of animal testing. Given that research methods far superior to animal testing exist, it is difficult to argue that animal testing is maintained solely because of the interests of animal breeders.
Furthermore, the claim that the media supports animal testing to boost ratings or generate interest through coverage of new drug development is also unconvincing. New drug development accounts for only a small fraction of the countless stories covered by the media; if new drug development itself were the key factor driving interest, research achievements utilizing alternative technologies—such as cell culture, organoids, or organ-on-a-chip—rather than animal testing would be equally newsworthy. Therefore, this argument lacks sufficient grounds.
In the same vein, the claim that pharmaceutical companies support animal testing solely to avoid liability in the event of adverse effects is also difficult to accept. Today, the drug development process incorporates a variety of alternative testing methods, such as cell-based assays, computer simulations, organoids, and organ-on-a-chip technologies, and regulatory agencies in various countries are gradually expanding the use of these methods. Nevertheless, in a significant number of research fields, animal testing is still utilized as part of the process to verify safety and efficacy. Therefore, it is difficult to conclude that pharmaceutical companies support animal testing solely to avoid liability.
The Scientific Utility of Animal Testing
The Greeks explain that differences in DNA lead to significant variations in the structure of organs and organ systems, the patterns of disease onset, and responses to treatments; furthermore, even among humans, different responses occur depending on factors such as gender and race. Of course, it is true that drug responses can vary depending on factors such as gender or genetic background. However, these differences are mostly a matter of degree, and in the absence of specific diseases or genetic abnormalities, there are also many physiological characteristics that are common to all humans.
The same is true for animals. While differences exist between species, there are quite a few animals that share many physiological similarities with humans. Mammals, in particular, have long been used in biomedical research because their hormonal systems and the basic structures of their major organs are largely similar to those of humans. Pigs, whose organ sizes and structures are similar to those of humans, continue to serve as important research subjects in various fields, such as organ transplantation research. However, these similarities do not automatically guarantee identical results in humans, and recently, various alternative testing methods have been developed and utilized to compensate for the limitations arising from interspecies differences.
When comparing humans and animals, there are cases where animal experiments actually provide more accurate and systematic results than those conducted on humans. Because humans are subject to various variables—such as living environments, dietary habits, genetic backgrounds, and social environments—it is extremely difficult to control the same conditions across time and space. Furthermore, it is not practically feasible to manage a large number of people in the same environment over a long period for research purposes. In contrast, laboratory animals can be managed relatively consistently under controlled environmental conditions, allowing for a clearer analysis of how specific factors influence the results. Therefore, while human studies often involve the complex interplay of multiple factors, animal testing offers the advantage of relatively easier control over variables.
Furthermore, animal experiments offer economic advantages compared to other research methods. For example, the white mouse—widely used as a laboratory animal—is relatively easy to breed and maintain, reproduces rapidly, and offers the advantage of securing strains with consistent genetic characteristics tailored to research objectives. In contrast, culturing human tissue or conducting research on human subjects requires high costs, complex technologies, and strict ethical standards. Of course, various alternative testing methods—such as organoids, organ-on-a-chip technologies, and computer-based predictive models—have been rapidly advancing in recent years, but as of now, they have not yet reached a level where they can completely replace animal testing in all fields of research. Therefore, in modern life science research, animal testing and alternative methods are used in a complementary manner.
Animal Testing and Ethical Debates
Of course, animal testing remains a subject of ongoing controversy not only from a scientific perspective but also from an ethical standpoint. As the number of households with companion animals increases and social awareness of the need to respect animal rights spreads, there are growing calls to respect animals not merely as research subjects but as living beings in their own right. Consequently, the debate over whether animal testing is ethically justified continues. There are also diverse opinions regarding whether adequate ethical frameworks—not just institutional ones—are sufficiently in place to support scientific research.
Researchers who conduct animal experiments sometimes hold memorial services to honor the laboratory animals sacrificed in the research process, arguing that without these sacrifices, modern medicine and the life sciences would not have advanced to their current levels. On the other hand, opponents of animal testing criticize such experiments as being closer to abuse than research when they are conducted without adequately guaranteeing animal welfare and rights.
However, in reality, it is not easy to immediately halt all animal testing. This is because animal testing is still utilized to some extent in various fields, such as pharmaceuticals, vaccines, medical devices, and disease research. Furthermore, even among those who oppose animal testing, there are differing views on the extent to which animal rights should be recognized.
Animal welfare advocates believe that humans have a responsibility to protect animals and ensure their well-being. Therefore, they argue that humans have a duty to provide appropriate environments and treatment to ensure animals do not suffer unnecessary pain. On the other hand, supporters of animal rights view animals as living beings with inherent rights, just like humans, and argue that they should not be used for research or industrial purposes. Another perspective explains that preventing unnecessary suffering in animals is the core of ensuring animal rights.
Ultimately, preventing animal abuse is the most crucial aspect of the animal ethics debate, and various positions—including the animal rights movement and the animal welfare movement—differ based on how this is to be achieved. The reasons why animals should not suffer and the extent to which this principle should be recognized remain important topics of social debate. Therefore, sufficient social consensus and continuous institutional improvements are necessary to determine, in practical terms, the level at which animal rights should be guaranteed and the systems and standards through which this will be achieved.
Is Animal Testing Still Necessary?
Summarizing the discussion so far, it is difficult to view as sufficiently substantiated the claim that animal testing is supported solely because livestock producers, media outlets, and pharmaceutical companies stand to gain economic benefits. Furthermore, animal testing has long played a crucial role in the advancement of medicine and the life sciences, and it continues to hold significant scientific value across various research fields today.
Of course, technologies capable of replacing animals—such as organoids, organ-on-a-chip, and AI-based predictive models—are advancing rapidly, and global efforts to reduce animal testing are expanding. Therefore, it will become increasingly important to actively utilize alternative testing methods wherever possible and to conduct animal testing only when absolutely necessary, and then to a minimum extent.
There are certainly ethical issues associated with animal testing. However, rather than outright rejecting animal testing itself, this challenge should be addressed by continuously strengthening ethical standards, minimizing the suffering of laboratory animals, and actively developing and utilizing alternative technologies. Animal testing remains one of the key research methods in the preclinical stage, and when used in a complementary manner with various alternative testing methods, it can lead to even more meaningful research outcomes. Therefore, rather than unconditionally rejecting animal testing, continuous efforts are needed to develop it in a way that balances scientific necessity with ethical responsibility.
