By Stephanie Eichberg
In 2012, a book appeared on the shelves of popular science that (re)acquainted the public with a medical revelation; namely that animals share with humans a wide range of acute and chronic diseases as well as psychological disorders, and that they can accordingly ‘teach us about being human’. From the point of view of the history of medicine, it appears strange that this is presented as ‘new’ knowledge, considering human-animal comparisons have long formed the backbone of anatomical, physiological and clinical research. No matter what historical period you investigate, you’ll find that the diseased bodies, brains and behaviors of animals have always been serving as surrogates for our own afflicted bodies, brains and behaviors.
Today, disciplines including Experimental Pharmacology, Genetics and Evolutionary Psychology provide modern medical researchers with a well-established scientific framework for practicing ‘zoobiquity.’ However, the resemblance of human and animal bodily structures and propensities for diseases has been exploited by physicians for their own therapeutic goals since antiquity. When the eminent German pathologist – and anti-evolutionist – Rudolf Virchow (1821-1902) maintained in 1875 that, “[b]etween animal and human medicine there is no dividing line – nor should there be. The object is different but the experience obtained constitutes the basis of all medicine,” he was not only drawing on a long-established practice of comparative anatomy and experimental physiology, but potentially, and maybe unconsciously, related to an even older tradition in which animals not only played a role in medicine but as medicine. Take any early modern materia medica, a published collection of substances with healing properties, and you’ll find that
“All Sorts of Medicine may be had from Beasts …some we take whole, of some but part, we oft-times in Physicke use whole creatures, as Foxes, Whelpes, Vipers, Cantarides, Frogs, Snailes, Wormes, Serpents; We also use some parts of them, as Liver, Heart or Braines; also of the Bones, as a Mans Scull, Marrow, Grease, Blood; likewise of the Excrements, as Haire, Urine, Dung, Spittle, Hornes, Honey, Waxe, Wooll, Sweate.” 
Carl Linnaeus also compiled a compendium of medical substances. Book I lists botanical substances, but the cover image also depicts snakes and a scorpion, only two of a myriad number of animals mentioned in his 1750 book Materia Medica, Regno Animali.
Arguably, consuming or using parts of an animal to cure (human) disease is not the same as gaining a better understanding of disease by comparing it with that of a similarly afflicted animal. But there is an underlying acknowledgement at play in both approaches: the make-up of human and animal bodies – ranging from bodily structures to vital spirits in early modern terms – was similar enough to cure one with the help of the other. The author of the above-quoted seventeenth-century materia medica inadvertently blurred the species boundary even further by listing human-based ingredients, such as ‘Mans Scull’, among beastly ones without bothering to differentiate (so much so, that it’s not clear whether the following ‘Marrow, Grease and Blood’ refers to those of humans or of animals). Next to animal-based medical ingredients – the stock and trade of healers for thousands of years – it was also common to think of diseases as transgressing the species barrier (the oldest example being the epileptic goats mentioned in the Hippocratic corpus). Thus, the ‘zoobiquitous’ method of learning from animal bodies and animal diseases has a long history. Why, then, has it become necessary to ‘rekindle’ this methodology?
The authors of Zoobiquity describe their realization that animals and humans share most ailments of body and mind as a ‘shifted boundary’, alluding to their previous conviction that the fundamental difference, i.e. the boundary between human and animals, must also be mirrored in the species’ susceptibility to diseases. At some point in the nineteenth- and twentieth centuries, human medicine and veterinary practice drifted apart, turning into two fundamentally different branches of medicine (the fact that in 1875, Rudolf Virchow felt the need to point out that there was no dividing line between the two disciplines is in itself an indication that this view was changing in the wake of medicine becoming scientific). On first reckoning, the human-animal boundary indicates a rather fixed barrier; yet, despite the split within the actual practice of human vs. animal medicine, the species barrier continued to be handled surprisingly fluidly within foundational research. In a cultural context, the sociologist Keith Tester referred to this flexible human-animal boundary business as a ‘demand for similarity’, constantly battling it out with an equally strong ‘demand for difference’. In a medical context, we could say that the need to use animals as proxies for the human body creates a demand for similarity, while the need to maintain a species barrier in order to preserve the unique and ultimately superior position of human medicine (based on a general belief in human superiority over animals) has invoked a demand for difference.
The metaphysical conviction of the human-animal difference has a long history in and of itself. During my research on the pre-modern understanding of the nervous system, in which the constant negotiation of the human-animal boundary took center stage, I found remarkable incidences of neuroanatomical and experimental research in which the experimenters’ gaze was distorted to an extent that anatomical structures, seen by the naked eye, were either described wrongly, or their functional interpretation was twisted and turned so as to remain in accordance with the overriding principle of human uniqueness – in other words, a ‘demand for difference’. The history of neuroscience is a rich field for exploring the flexibility of the human-animal boundary in science as well as philosophy because the functions of the brain and nerves have always been tightly connected to debates on what makes us human, whilst the very concepts related to those debates (sense perception, cognition, pain, emotion, amongst others) have, then and now, been explored in humans and animals.
Generally, though, the laboratory remained and remains the place where potential differences between species are consistently made to disappear: where a rat’s brain can be turned into an object that is representative of all mammals’ brains, including the human brain; where human researchers dip into and extrapolate their own subjective memory or knowledge of pain to assess its presence or degree in an experimental rabbit; where the animal body, any animal’s body, can become a diseased entity to be treated, operated upon or medicated with chemicals so that the knowledge gained can be applied to human patients. A shared psychology might not (yet) be fully accepted, but scientists have begun to remind themselves that not only bodies, but also human thought and emotion have evolutionary roots, and that an acknowledgement of shared psychological mechanisms and disorders would present us with a basis for ‘new’ research – notwithstanding the fact that experimental psychiatry has long been extrapolating observations from ‘beastly’ experiments. Ranging from infamous isolation experiments with infant macaques to explore childhood disorders to spiders whose web formation went awry after absorbing drugs or even the blood serum of human catatonic schizophrenic patients, the range of conditions researched and animals used to find out about our diseased minds is truly astonishing. So again: what’s new?
In fact, following the authors of Zoobiquity on their highly readable and entertaining journey towards realizing the extent to which animals share common and rare ailments with us, it still comes as a surprise to learn that today’s physicians and veterinarians do not communicate their shared patient (hi)stories at all, let alone exchange treatment options. As indicated above, out in the field of medical practice, human and animal diseases are still conceived as fundamentally different even though animal-to-human extrapolation of medical knowledge has been the building block for understanding and treating both.
Zoobiquity accordingly sets out to rectify the situation by building bridges between physicians and veterinarians for the therapeutic benefit of their respective patients. As it is, behind the scenes, academics and scientists have been busy working out a way of doing the same, with movements like One Health or One Medicine representing attempts to bring the two medical realms – animal and human – together.  It is tempting to say that we’ve come a long way, were it not for the fact that this ‘new’ knowledge is old enough to have a history of its own.
After her PhD studies at the Centre for the History of Medicine and Disease at Durham University and a Teaching Fellowship for History of Medicine courses at UCL, Stephanie Eichberg is currently a research associate for a project at the Centre for Literary and Cultural Studies in Berlin which explores the neurosciences between natural science and cultural studies. Her research focuses on the mind-body problem, the human-animal boundary in neuroscience and the phenomenon of pain.
 The term signifies a ‘species-spanning approach to the diagnostic challenges and therapeutic puzzles of clinical medicine’; see Barbara Natterson Horowitz and Kathryn Bowers, Zoobiquity. What Animals Can Teach Us about Being Human (London: Virgin Books, 2012), 18.
 Quoted in Zoobiquity,7.
 Thomas Brugis, The Marrow of Physicke. Or, A learned Discourse of the severall parts of mans Body. Being a Medicamentary….(London: Printed by Richard Hearne, 1640), 89.
 [Hippocrates], On the Sacred Disease (De Morbo Sacro, c. 410 B.C.). Further examples can be found in Vivian Nutton, Ancient Medicine (London and New York: Routledge, 2004), 77.
 Barbara Natterson Horowitz and Kathryn Bowers, Zoobiquity. What Animals Can Teach Us about Being Human (London: Virgin Books, 2012), 12.
 Keith Tester, Animals and Society. The Humanity of Animal Rights (London and New York: Routledge, 1991), 88.
 See Michael Lynch, ‚Sacrifice and the Transformation of the Animal Body into a Scientific Object: Laboratory Culture and Ritual Practice in the Neurosciences’, Social Studies of Science 18:2 (1988) 265-289.
 The neuroscientist Jaak Panksepp has been at the forefront of advocating the ‘new’ knowledge of shared emotions in humans and animals with his book Affective Neuroscience. The Foundations of Human and Animal Emotions (New York: Oxford University Press, 1998).
 See, for example, J.D. Keehn, Animal models for psychiatry (London et al: Routledge & Kegan Paul, 1986). For more on the on the drugged spiders’ webs experiments, see Noever, R., J. Cronise, and R. A. Relwani, ‘Using spider-web patterns to determine toxicity’, NASA Tech Briefs 19:4 (01 April, 1995),:82. Published in New Scientist Magazine, 29. April 1995.