The biology and culture of body fluids: from the physiology of saliva and earwax to the anthropology of the body, inspired by Ruben Verwaal's book Blood Sweat and Tears.

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The biology and culture of body fluids: from the physiology of saliva and earwax to the anthropology of the body, inspired by Ruben Verwaal's book Blood Sweat and Tears.
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Introduction

Have you ever wondered why substances produced by our own bodies evoke such extreme emotions? This article analyzes the biology and culture of bodily fluids, using saliva and earwax as primary examples. You will discover that the significance of secretions stems not from their chemical composition, but from their context. We will trace a path from physiology through the anthropology of disgust to population genetics. The goal is to understand the conflict between biological homeostasis and the cultural pursuit of sterility, demonstrating that the body is not merely a collection of tissues, but a dynamic ecosystem.

Saliva: A Fluid of Shifting Status and Complex Function

Saliva is an example of matter whose status changes based on the direction of its flow. Within the oral cavity, it is essential; outside of it, it often provokes revulsion. It can be a remedy or a diagnostic tool in a test tube, yet it becomes a symbol of insult when used to spit on another person. It is not chemistry, but intention and social relationship that define its meaning. Biologically, it is a complex environment containing mucins, enzymes, and antibodies. It enables the digestion of starch, protects tooth enamel, and serves as an indispensable medium for taste perception. Modern science treats it as a valuable source of medical data—provided it is placed in a sterile container—which shifts its status from filth to information.

The Biological Value of Saliva Revealed Through Its Absence

The value of saliva is often only recognized when there is a deficiency, known as hyposalivation. The lack of this fluid leads to impairments in speech and swallowing, as well as an increased risk of infection. Historically, science moved from speculations about the fermentation of food to empirical research on dissolution. Lazzaro Spallanzani's experiments helped distinguish mechanical grinding from the chemical action of juices. Over time, medicine began to view spitting in public spaces as a threat, particularly after Robert Koch discovered the tubercle bacillus. This led to the introduction of solutions such as the pocket spittoon, known as Blauer Heinrich. This transition shows that modern hygiene does not eliminate physiology, but rather alters its infrastructure to render secretions invisible.

Saliva as a Medium of Power and Regeneration

In many cultures, saliva was treated as a carrier of healing power. These practices, present in the Bible and the temples of Asclepius, correlate with the fluid's actual biological properties. Saliva contains growth factors and peptides, such as histatins, which support cell migration and wound closure. This explains why injuries in the oral cavity heal faster than skin wounds. However, these healing properties do not make it inherently safe. The oral cavity possesses an extensive microbiome; therefore, contact between foreign saliva and an open wound can introduce pathogens and trigger an infection. Medicine thus teaches us conditional thinking. Saliva is neither unequivocally good nor bad; its effect on the organism depends on context, the presence of microorganisms, and the immune barrier.

Summary

The analysis of saliva and earwax reveals a paradox of our civilization. In striving for an ideal of sterility, we often attempt to remove the very mechanisms that protect us. A healthy organism is not one devoid of secretions or bacteria, but rather a functioning ecosystem. Aesthetic cleanliness can sometimes conflict with biological health. The biological truth about humans is less sterile than our culture. Life, in its essence, is moist and inextricably linked to its own physiological products.

📚 Based on

Blood Sweat and Tears

👤 About the book's author

Ruben Verwaal

Erasmus University Medical Centre

Ruben E. Verwaal is a Dutch historian of medicine and science and a museum curator specializing in the cultural and physical history of the human body, bodily fluids, and sensory impairment. He earned his doctorate from the University of Groningen in 2018 with research examining bodily fluids in eighteenth-century chemistry. Verwaal serves as curator of medical collections at Erasmus University Medical Centre (Erasmus MC) in Rotterdam and has held research fellowships at Durham University's Institute for Medical Humanities. His scholarship focuses on how understandings and cultural perceptions of bodily fluids changed from early modern humoral theory to modern scientific practice, as well as the history of deafness and healthcare heritage. His major scholarly monograph, Bodily Fluids, Chemistry and Medicine in the Eighteenth-Century Boerhaave School (2020), analyzes the transformative role of chemistry in early modern physiology.

Mind map: The Biology and Culture of Bodily Fluids

📖 Glossary

ABCC11
Gen odpowiedzialny za transport białek, którego warianty determinują typ woskowiny (sucha lub mokra) oraz intensywność zapachu pachowego.
Hiposalivacja
Stan obniżonej produkcji śliny, prowadzący do problemów z połykaniem, mówieniem oraz zwiększonego ryzyka infekcji jamy ustnej.
Histatyny
Peptydy obecne w ślinie, które pełnią funkcje przeciwdrobnoustrojowe i wspomagają regenerację tkanek poprzez przyspieszanie gojenia ran.
Polimorfizm pojedynczego nukleotydu (SNP)
Zróżnicowanie w jednej pozycji pary zasad w DNA, które może wpływać na cechy fizyczne organizmu, np. konsystencję cerumenu.
Iatrochemia
Wczesna forma chemii medycznej z XVII wieku, traktująca ciało jako przestrzeń reakcji chemicznych i fermentacji.
Sialorrhea
Nadmierne wydzielanie śliny lub trudności w jej kontrolowaniu, często związane z problemami neurologicznymi.

Frequently Asked Questions

Why can saliva be simultaneously a remedy, a diagnostic tool, and a symbol of insult?
Saliva functions as a remedy due to its properties that support mucosal healing and provide antimicrobial protection, while it serves as a diagnostic tool once collected in a test tube. Simultaneously, it can become a symbol of insult and degradation when intentionally spat upon another person.
1. How did science begin to perceive the function of saliva and how does its absence prove its value to the organism?
2. Science began to perceive saliva as an essential element of bodily functioning by analyzing the pathologies of its deficiency (hyposalivation). A lack of saliva leads to specific dysfunctions, such as difficulties in speaking and swallowing, taste disorders, and an increased risk of tooth decay and oral infections.
3. How does the cultural and religious perception of saliva as a remedy correlate with its actual biological properties?
4. The cultural and religious perception of saliva as a cure stemmed from it being treated as a personal medium transmitting power, rather than from knowledge of its chemical composition. However, modern biology indicates that saliva contains real factors that support tissue regeneration and wound healing, such as histatins or growth factors.
5. Do the healing properties of saliva make it safe, and how has medicine changed the perception of spitting in public spaces?
6. Healing-promoting properties do not make saliva safe, as the microbiome present in it can introduce microorganisms into a wound and increase the risk of infection. Robert Koch's discovery of Mycobacterium tuberculosis changed the perception of spitting in public spaces, transforming sputum into a visible carrier of an infectious agent, which led to the introduction of bans and the use of special containers for secretions.
7. How have modern hygiene and the fight against diseases changed our approach to bodily secretions in public spaces?
8. Modern hygiene aims to isolate secretions in special containers and devices to make them invisible and control their circulation. Biological activities have been shifted from public to private spaces, resulting, among other things, from rational foundations of public health and the fight against pathogens.
9. Why can the same substance be considered an act of violence, dirt, or a valuable source of medical data?
10. How a given substance is perceived is determined not by its chemical composition, but by intention, relationship, context, and location. Spitting is an act of violence because it violates bodily autonomy without consent, whereas saliva in a sterile laboratory container changes status from dirt to valuable medical data.
Why is earwax an example of a conflict between biology and culture?
Earwax is an example of a conflict between biology and culture because it serves a protective function for the organism, while the culture of cleanliness dictates that it be treated as dirt and removed. It constitutes a case study in the clash between body surface homeostasis and the aesthetics of cleansing.
When does the presence of earwax in the ear become a medical problem, and when is it a natural function of the organism?
Earwax is a natural function of the organism because it plays a protective role, moisturizes the auditory canal, and hinders the growth of microorganisms. It becomes a medical problem only when its accumulation causes symptoms, prevents an examination of the ear, or when the material is mechanically pushed deeper.
How has the approach to studying bodily secretions changed over the centuries, and what does this say about the development of science?
The approach evolved from theories of fluid quality and temperament, through the anatomical perception of physical obstacles and sensory chemical examinations (tasting, smelling), to modern laboratory methods that separate the researcher from the sample. This process shows that science does not develop through abrupt revolutions, but through overlapping paradigms and the gradual replacement of sensory cognition with objective instruments.
How do hygiene tools influence our perception of what constitutes dirt or disease?
Hygiene tools redefine norms of cleanliness, creating expectations for the removal of body elements that were previously not perceived as a problem. In this way, technology can transform natural physiological processes into aesthetic defects or mistakenly identify them as diseases.
Is the nature of bodily secretions constant and independent of external factors?
The nature of secretions is not constant, as their properties depend on genetic factors, such as polymorphism in the ABCC11 gene, which determines the type of earwax (dry or wet). Furthermore, the same substance can be considered physiological or pathological depending on its quantity, location, and functional effects.
Can genetic differences in earwax type be used to define ethnic groups or social hierarchies?
No, a single biological trait cannot serve to define the essence of an ethnic group or establish a value-based category. There are no grounds for deriving a hierarchy of individuals based on the frequency of a specific allele.
What does the analysis of bodily secretions teach us about the relationship between biological health and the cultural concept of purity?
The analysis of secretions shows that the cultural concept of purity often equates health with the invisibility of the body's material traces, whereas a biologically healthy organism is an ecosystem that requires the presence of secretions to function properly. This indicates a paradox in which substances socially regarded as dirt actually participate in maintaining biological order and perform protective functions.

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