The End of Animal Experimentation

Every year hundreds of millions of animals are used both by universities and the pharmaceutical industry as experimental subjects. Members of the public who oppose animal experimentation have taken issue with this, pointing out that many experiments are extremely cruel. Scientists have maintained that their experiments are just the price we have to pay if we are going to find new cures for human diseases, leading to an acrimonious debate between the two sides. Now new technological advances have rendered this argument moot.

Animal experimentation is nothing new. It began in ancient Greece, primarily with Aristotle and reached its apogee with the Greek doctor Aelius Galen in the third century CE. When modern biomedical research began to develop in the 17th century it was initially viewed as a hobby carried out by a few wealthy gentlemen. This changed dramatically with the enormous increase in government research funding that followed WWII when science became a real profession. Nowadays millions of scientists perform biomedical research and, as a result, there has been a corresponding increase in the use of experimental animals and in the number of scientific publications where scientists report their results. Unfortunately, it is clear that the vast majority of these publications are rarely cited by anybody apart from their authors and contribute little, if anything, to either scientific discourse or the cure of human diseases.

Since antiquity, scientists have considered animals as stand-ins or models for humans. We don’t do most experiments on humans for ethical reasons; we use animals instead. The idea has always been that if we can cure a disease in an animal then we can cure it in a human. Regrettably, this has rarely proved to be the case. Most diseases have been “cured” in animals many times over, but have failed to impact human treatment, illustrating the fact that for many important purposes animals are poor substitutes for humans and provide inadequate models for human diseases.

Moreover, even when animal research has been useful there have always been questions regarding its ethical appropriateness. In the 17th century, Descartes’ mechanical philosophy encouraged the view that animals were merely unfeeling machines allowing scientists to ignore any potential ethical problems that might arise from their use. Eventually members of the public began to question what was going on. The philosopher Jeremy Bentham (writing in the 19th century) reframed the debate around animal experimentation asking, “The question is not, Can they reason? nor Can they talk? but, Can they suffer?” Since that time, groups who oppose animal experimentation have thought about the issue primarily from Bentham’s point of view. Whatever valuable information they may provide, animal experiments are certainly cruel, and animals certainly suffer.

Now things are changing fast. Since the beginning of the 21st century, new technologies have been developed that enable scientists to use human tissues rather than animal subjects for their experiments, thereby avoiding ethical problems associated with cruelty to animals and producing data that is directly relevant to humans. Gene sequencing studies have allowed scientists to start understanding the molecular fabric of humanity in great detail and have highlighted numerous critical differences between humans and animals. Importantly, the development of stem cell technology has enabled scientists to generate human tissues for an ever-increasing number of experimental purposes. The discovery of human “induced pluripotent stem cells” (iPSCs) has meant that such cells no longer have to be sourced from human embryos, something that was previously viewed as an ethical barrier by many people. The use of stem cells has led to the development of organoids, meaning entire human organs grown from scratch in a laboratory. Even parts of the brain, the most complicated organ in our body, have been grown this way. Organoids from different tissues can be linked together using microfluidic methods producing human-derived tissue arrays of ever-increasing complexity and sophistication. Such human-based organ systems provide much better experimental paradigms for drug development and investigating other biomedical problems than the use of animals. CRISPR-enabled gene editing methods now allow scientists to make genetic changes within stem cells derived from human tissues so that they genuinely reflect the entire spectrum of human diversity, something that also cannot easily be achieved using animals. Additionally, the development of live human imaging methodologies has allowed the assessment of human physiology and pathology in real time. Techniques like these are rapidly making animal experimentation obsolete. Scientists who conduct experiments on animals don’t like to be told that their research is no longer at the cutting edge, but the era of animal experimentation is coming to an end. Animal experiments are looking terribly old fashioned—even to scientists. It’s just not good science anymore.

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