The Apples and Oranges of Animal Research

In the debate about animal experimentation, there are numerous angles to consider that can easily become confused if they are not examined in context. One of the most common arguments that the research industry states to justify its use of animals is that animals such as primates, dogs, and even rats and mice are similar enough to humans that testing on them may yield results that can be applied to human health. This study looks at the similarity/difference argument in particular, and works from the thesis that “a similarity/difference (S/D) calculus is not the bottom-line consideration in the evaluation of animal models of biomedical and psychological research.” In other words, though certain animals may be similar to humans in a variety of ways, this does not mean their use in biomedical research is scientifically valid (or ever ethically justified).

The author delves into this thesis by first unpacking the concept of model validity. In simple terms, the validity of a model is how closely it can be said to predict similar data outcomes in humans. Though this a simplification, and there are different kinds of “validity” depending on the type of study being done (and in what discipline the study is taking place), for the purposes of this summary, “validity” is best understood as how well any given animal model will predict a human health outcome. From this perspective, the author notes that “the relation between validity and the problem of evaluation of animal models is complex and often misunderstood.” Based on a host of background research, the author lists three ways that animal models fall short in terms of validity:

1. An animal model is never finally or fully validated.
2. Even an animal model for which some degree of validation has been demonstrated is not necessarily a contribution to understanding or treatment effectiveness.
3. Most animal models in biomedical and psychological research are not validated, even in the limited sense described.

With these three statements in mind, the author remarks that it is vitally important to understand animal models “a) in actual practice; b) as presented in the media and white papers by animal research advocates; and c) as they are supposed to work.” According to the author (and, it should be noted, many anti-vivisection advocates) there is a disconnect among these three.

If the animal models have limited validity, “the animal model is limited to a hypothesis generator. It is a locus of discovery not a locus of justification.” Therefore, though animal models may help us generate questions about human health, they cannot answer those questions for us. However, as the author notes, “science traditionally has used other kinds of models to generate hypotheses, beside animals — for example, machines (most recently the computer as a model of the nervous system) and mathematical models (to predict the molecular structure of therapeutic drugs and toxic chemicals). Of course, another locus of discovery is the target itself.” At some point in time, any techniques used on a model has to be applied to the target in a clinical setting.

Though this article does not go into ethical arguments for questioning animal experimentation, it does present a compelling scientific case, and in doing so gestures towards an ethical shift. If there are many models that we can use to generate hypotheses about human health that do not involve the captivity and suffering of sentient beings, then we should have a harder time justifying animal experiments altogether. The idea that similarity/difference is, on its own, a way to validate animal models is simply false. If we cannot validate animal models on this and various other axes, turning to alternatives is not only scientifically, but ethically, more sound.