The Perineum and the Saint

The Christian doctrine of the Fall owes much of its modern architectural rigour to Saint Augustine of Hippo (354–430). While one might avoid a full theological discourse here, it is undeniable that Augustine’s interpretation of the Garden of Eden narrative has profoundly shaped various—though not all—strands of Western Christian thought.

It is perhaps Augustine's specific attitude towards humanity that manifests most memorably in a somewhat unholy reference to human (and particularly female) anatomy. His assessment of human nature post-Lapsarian was fundamentally pessimistic, viewing humanity as a massa peccati (a mass of sin), naturally inclined toward evil due to an inherited corruption of the will. This dim view may have its roots in his early adherence to Manichaeism—a dualistic philosophy that regarded the material world and the flesh as inherently corrupt. Consequently, a phrase frequently ascribed to him describes mankind as being born "between urine and faeces"—or, in the Latin, inter faeces et urinam nascimur. By this, he makes a direct, if crude, reference to the perineum.

The term perineum entered the English lexicon in the early 15th century via Late Latin, having been borrowed from the Ancient Greek perinaion. Its roots are a combination of peri- (meaning "around" or "near") and inan or inein ("to empty" or "evacuate"). It describes that specific anatomical site between the anal and urethral openings where, in the female, the vaginal opening is situated.

However, a scholarly convenience is at play here: while Augustine is the perennial source for this quote, the phrase does not appear in any of his surviving works. Hence, one often finds the phrase "attributed to Saint Augustine" used. Its earliest known appearance in print dates to an 1875 edition of Arnobius of Sicca’s Arnobii Adversus Nationes Libri 7, edited by August Reifferscheid. A variant, inter stercus et urinam nascimur ("we are born between dung and urine"), appears in 17th-century texts, such as Joannes Christophorus Avemann's 1695 Disputatio medica inauguralis, where it was actually attributed to the Roman philosopher Seneca. To further muddy the hagiographic waters, the phrase has also been linked to Bernard of Clairvaux.

Despite the lack of primary evidence, the phrase persists in modern theological and literary circles to illustrate the "messy" physical reality of birth in contrast to spiritual ideals. This juxtaposition is especially striking when compared to traditional religious iconography. Where medieval depictions of the Nativity or the Birth of Mary are typically sanitised and ethereal, this "Augustinian" sentiment forces the reader to confront the visceral proximity of the sacramental and the excremental. Without the convenience of this attribution, writers seeking to highlight this tension would find themselves without their most potent rhetorical weapon.

Moving beyond the polemics of the saints, the pelvic floor remains a critical anatomical region. A vast array of clinical issues can arise from the natural process of childbirth alone, quite independent of patristic commentary. While the term pelvic floor dysfunction has faced academic criticism for its lack of medical specificity, the very breadth of the problems it encompasses—from urinary incontinence to pelvic organ prolapse—makes the term particularly telling. We indeed enter the world via a complex anatomical threshold, a reality that persists whatever theological interpretations are put on it.

Skipping Guts - Addendum

 In a previous post, I suggested that it might be better to equate gut length to height rather than textbooks giving them absolute lengths. In so doing, I referred to a physiological 70 kg man (and 60 kg woman) that formed the standard against which comparisons could be made. While height was not proposed for a standard man or woman, specific heights were proposed to accompany these physiological standards.

The 70 kg man (and 50 kg woman) reference was primarily established by the International Commission on Radiological Protection (ICRP) to create a uniform model for radiation dose calculations and anatomical comparisons.

• Reference Man (70 kg): The standard height is 170 cm (approximately 5'7"). This "Reference Man" was defined in ICRP Publication 23 (1975) as a Caucasian male between 20 and 30 years of age living in a temperate climate.
• Reference Woman (60 kg): The ICRP's updated standard for a "Reference Woman" (often used alongside the 70 kg man) is typically 60 kg with a height of 163 cm (5'4"). In some older or different physiological contexts, a 50 kg woman is often paired with a height of 152–158 cm (5'0"–5'2") to maintain a similar Body Mass Index (BMI) of approximately 20–22.

The Layered Brain

As a student, I was introduced to the architecture of the brain through a specific phylogenetic lens, using the terms archicortex, paleocortex, and neocortex. While the term archaeocortex was still in use at the time, it has since largely been superseded by archicortex. These designations were more than mere labels; they reflected a chronological narrative of evolutionary appearance, categorised from oldest to newest.

1. Archicortex: The phylogenetically oldest component of the cerebral cortex, primarily represented by the hippocampus and the dentate gyrus.

2. Paleocortex: Considered the intermediate or "old" cortex, it is fundamentally associated with the olfactory system.

3. Neocortex: The newest and most sophisticated addition, appearing first in early mammals and now accounting for approximately 90% of the human cerebral cortex.

While this three-part schema remains a useful pedagogical starting point, it is, in truth, a gross simplification. Each section consists of distinct neuronal layers, and the phylogenetic order itself is a matter of debate. While many sources cite the archicortex as the most ancient, some neuroanatomists argue that the olfactory system appeared first, or at least concurrently. I suspect the professor who taught us this order belonged to the latter school of thought. In a lecture on the cranial nerves, he adopted a similarly phylogenetic approach: he argued that the olfactory nerves were the oldest not just anatomically, but in terms of how life first "contended" with its environment. The first interaction was chemical; what we call "smell" is, in effect, the detection of airborne molecules. It requires little imagination to see this as a primary evolutionary necessity.

He extended this logic to the remaining cranial nerves. If the first challenge was chemistry, the second was electromagnetic radiation—specifically, the spectrum we call light. Thus, the optic nerve followed. Whether this specific evolutionary sequence is entirely accurate is perhaps a moot point; its value lies in providing an entry into the brain’s daunting complexity. It suggests an underlying logic to biological structure, reinforcing the idea that the brain is not a single, unitary object, but a record of evolutionary history.

This perspective aligned with the Triune Brain hypothesis, a theory that was particularly popular during my student years. Originated in the 1960s by Paul MacLean and popularised by Carl Sagan in his 1977 book The Dragons of Eden, the hypothesis used the archicortex, paleocortex, and neocortex as the biological foundation for a theory of three distinct evolutionary "brains" residing within the human skull. MacLean’s model was an expansion of these cortical categories; he integrated them with deeper structures, such as the basal ganglia (or "R-complex"), to suggest a functional hierarchy of behaviour that moved from primal survival to complex reasoning.

The enduring popularity of the Triune Brain in the public imagination is a testament to the power of compelling narrative in popular science. Through Sagan’s prose, a hypothesis was "frozen" in the public consciousness, persisting long after the scientific community had moved toward more integrated models. Today, neuroscience has largely moved past these "additive" layers in favour of network neuroscience and neuroplasticity, which view the brain as a highly interconnected system rather than a series of autonomous chronological strata.

In the decades since, the Triune Brain hypothesis has fallen out of favour. However, I wonder if the theory still holds value as a pedagogical "thinking tool" or an object for critical analysis. It could serve as a rigorous exercise for students—not merely as a historical footnote, but as a challenge. It is a rare and perhaps necessary experience in scientific education to be handed a once-revered hypothesis with the instruction: "Explain exactly why this is now considered incorrect."

Penultimate Circulation Figure

My notes say that this figure depicting the human circulation is from a textbook entitled The Human Body - An Introduction to Structure and Function by Faller and Schuenke.

This is the penultimate such illustration in this series. I have only one more. Please be sure to click the label marked 'The Circulation' to access all such posts. My idea was to illustrate how the same topic can be illustrated in very different ways.