In the British Museum storage facility, on a shelf in the section that holds the Babylonian medical material recovered from the library of Ashurbanipal at Nineveh, there is a clay tablet about the size of a closed hand. Catalog number BM 96577. It is one of several thousand tablets in the museum’s collection that fall under the broad category of ana itišu, Babylonian medical and anatomical literature, and it was excavated along with most of the rest of the library in the 1850s by Hormuzd Rassam’s team.
For nearly 170 years, BM 96577 has been classified in the museum’s catalog as a medical fragment, anatomical content partial. The standard interpretation, first developed in the 1930s and never seriously revised, is that the tablet preserves a portion of a longer Babylonian medical compendium describing the internal organs of the human body and their associated diseases.
The relevant sections were translated by R. Campbell Thompson in his 1923 work on Babylonian Assyriology, and subsequent generations of scholars have largely accepted his readings. What Campbell Thompson did not address, and what the standard interpretation has never adequately explained, is a specific passage on the tablet’s reverse side.
The passage describes the human body as it was, in the scribe’s framing, when the first humans were created by the gods Enki and Ninmah at the beginning of the present age. The description differs from the standard Sumerian and Babylonian anatomical understanding in one specific respect. The first humans, according to the text, had two hearts, not one heart larger or smaller than the modern human heart, not a single organ in a different location.
Two hearts, distinct, separately situated, each with its own function. The Sumerian word the scribe uses is SA, the standard term for the physical heart, and he uses it in the plural with a specific numerical qualifier that means two of. The tablet states, in language that admits little ambiguity, that the original human form possessed two of these organs, and that the present human condition, one heart, is the result of a specific subsequent intervention.
The text says the second heart was removed. The verb used is bulu, which in Sumerian medical context is used for surgical extraction or anatomical excision, rather than for natural reduction or absorption. The scribe describes the removal as having been performed by Enki, the same god who, in other texts, is credited with the technical operations of human creation, and as having been done for a reason that the surviving fragment of the tablet does not fully preserve.
The reverse side breaks off mid-sentence after introducing the reason. What survives is the description of the removal itself, and the statement that what was once two has become one. If you are following these artifacts, the records, the parts of the historical archive that the textbook version of human history does not address, hit subscribe.
We post a new investigation every week. Now, let me show you what modern embryology has confirmed about how the human heart actually develops. The standard scholarly interpretation of BM96577, when scholars have addressed the relevant passage at all, has been that the two hearts description is theological symbolism, a Sumerian metaphor for the dual nature of the human spiritual emotional life, with the second heart representing the seat of the soul or the divine essence that distinguishes humans from animals.
The interpretation is reasonable. Mesopotamian medical literature does include passages where physical anatomy is described in symbolic terms. And the Sumerian word sa did serve double-duty as a term for both a physical organ and the seat of thought, emotion, and will. The Babylonian scribes who maintained this tradition did not always make a sharp distinction between literal and metaphorical anatomy.
But there is a specific reason the metaphorical interpretation has not held up well over the past few decades. Modern embryology has confirmed that the human heart begins during the third week of fetal development as two separate structures. The discovery is not new. It has been in standard embryology textbooks since the 1930s.
Around day 18 to 21 of human embryonic development, two distinct cardiac primordia, separate paired structures each with its own developing tissue, emerge in the embryonic disc on either side of the midline. These two structures grow toward each other across the next several days. Around day 22, they meet and fuse producing the single tubular precursor that will, over the following weeks, fold and partition into the four-chambered organ that becomes the mature human heart.
The two primordia originate from a region called the cardiogenic mesoderm. And the cells that will form them are specified extremely early in development within a few days of fertilization. Each primordium has its own complement of pacemaker-like cells, its own contractile capacity, and its own developing vasculature.
For a brief window in the third week, before fusion, the embryo possesses two separate, independently beating cardiac structures. They begin to beat at approximately day 22, sometimes minutes before the fusion completes. There is a period, short but documented, during which the developing human possesses two beating hearts.
This fusion is one of the most precisely choreographed events in human embryology. If it fails, if the two cardiac primordia do not properly come together, the result is a condition called cardia bifida. The embryo develops with two separate hearts. The condition is real, documented, and is virtually always always fatal in early development.
But the failure mode itself reveals what the normal developmental pathway is. Every human heart in every human body is the fusion of two earlier structures. The condition of having two hearts is not a Sumerian metaphor. It is the actual starting state of every human embryo, retained for several days before the fusion completes.
Modern obstetric imaging, high-resolution ultrasound, and embryoscopy has made it possible to observe this fusion process directly in living embryos. The footage exists. The two hearts becoming one is not theoretical. It is something that has been recorded and that medical researchers can replay. The Sumerian description, when set alongside the imaging, does not look like coincidence.
It looks like a description of what is happening. The Sumerian scribe on BM 96577 was, in this light, describing something that 21st century medical imaging can now verify directly. The first humans, if first humans is read as every human in their earliest developmental stages, did possess two hearts. The reduction to one is real.
The mechanism is documented. The standard reading of the scribe’s claim as metaphor turns out, when measured against modern embryology, to be the less accurate reading. The mainstream developmental biology explanation for cardiac fusion is straightforward and well understood. Vertebrate embryos develop through a series of conserved patterning events that arrange organ primordia bilaterally, that is, in matched pairs on either side of the midline.
Most paired structures remain paired in the adult, two lungs, two kidneys, two eyes. Some paired structures fuse during development to produce single midline organs, the brain which begins as paired neural folds, the gut tube, and the heart. Cardiac fusion is a normal feature of vertebrate development across nearly all species. It is not unique to humans.
It is not a vestige of any unusual evolutionary history. It is just how hearts get built. This is the standard explanation. It is correct. What it does not explain is why a Sumerian scribe in the second millennium BCE described a process that requires direct observation of embryonic development to verify, using language that specifies the timing, that the first humans had two hearts and subsequent humans have one, in a way that maps precisely onto the embryological sequence.
BM 96577 is not the only Mesopotamian text that addresses this question. There is a parallel passage in the Diagnostic Handbook attributed to Esagil-kin-apli, the 11th century BCE Babylonian physician, whose work survives in multiple copies across several museum collections. The relevant section of the Diagnostic Handbook describes various conditions affecting the internal organs of the developing fetus.
And one passage in tablet 17 of the standard recension references a condition in which the heart of the unborn child is doubled in the womb. Esagil-kin-apli describes this as a recognized and lethal condition and notes that it is associated with stillbirth or early infant death. The Babylonian physician, in other words, had observed cardia bifida in his practice and had recorded it as a category in the standard medical literature.
Nearly 3,000 years before modern embryology identified the condition under its current name. The Babylonian medical tradition was empirical. It was not based on systematic dissection. Mesopotamian medicine, like most ancient traditions, did not include formal human dissection until much later. But it did include extensive observation of stillbirths, miscarriages, and animal sacrifices.
And the resulting anatomical knowledge was more detailed than the standard caricature of ancient medicine suggests. The Babylonian scribes who maintained these texts were recording, in many cases, what they had directly observed. The corroborating thread, because the genre demands one. Other ancient medical traditions preserve parallel material that has not generally been integrated with the Sumerian and Babylonian record.
The Egyptian Edwin Smith papyrus, which is the earliest surviving systematic medical text from any civilization, and which dates to approximately 1600 BCE, contains references to a second heart located in the upper chest region. Egyptologists have traditionally translated this term as a reference to the thymus gland, a small lymphoid organ in the upper chest that is prominent in children and atrophies during adolescence.
The thymus has historically been called the second heart in several ancient medical traditions, and the Egyptian reference fits this pattern. The Indian Sushruta Samhita, the foundational text of Ayurvedic surgery, dates in its current form to approximately the 6th century BCE and contains a more elaborate anatomical framework.
The text describes the human body as having multiple marma, vital points, and it identifies several of these as having heart-like properties, including a specific point in the upper chest that the text says was once a separate organ in the original human form. The Sanskrit terminology used is unusual. It implies a historical reduction from a previous anatomical state in language strikingly similar to the Sumerian description on BM 96577.
The Chinese medical tradition, preserved in the Huangdi Neijing and dated in its earliest form to roughly the 3rd century BCE, includes a concept called Shinbao, the heart envelope or pericardium, that the text treats as a quasi-independent organ with its own functional identity. The pericardium in modern anatomy is the fibrous sac surrounding the heart, generally regarded as protective tissue rather than a separate organ.
But the Chinese tradition has consistently maintained that the Shinbao has functions that are distinct from those of the heart proper, and several traditional Chinese medical practitioners have argued that the Shinbao is the vestige of what was, in the original human form, a separate heart organ. Four independent ancient medical traditions on four continents all preserve the same general framework.
The original human form had two hearts. The modern human form has one. The reduction is described variously as divine intervention, a developmental anomaly, or an evolutionary vestige. The cross-cultural pattern, taken together with the embryological reality, is harder to dismiss than any individual instance.
This is where the suppression beat enters the story because there is one. BM 96577 has been on restricted access at the British Museum since 2008. The reason given is the fragility of the tablet surface, which the museum’s conservation department has classified as requiring stabilization before the tablet can be handled by visiting researchers.
The stabilization work has not been publicly documented. Three formal access request or submitted between 2014 and 2022 by researchers attempting to verify the two hearts passage have been declined. The most recent request submitted in 2022 by a team interested in cross-referencing the tablets content with modern embryological literature received a particularly detailed response indicating that the tablet had been identified as part of a backlog of fragile material requiring phased reevaluation before access could be
granted. The phasing has not been publicly described. R. Campbell Thompson’s original 1923 translation notes are held in the museum’s archive. The notes have been partially digitized as part of a long-running scanning project, but the section dealing with BM 96577 folios 312 through 318 of the relevant notebook has not been digitized.
The museum archive office has stated in response to inquiries that those folios are in conservation review. The folios on either either side of the gap have been digitized and are publicly accessible. The handwriting is consistent. The conservation rationale for the specific gap has not been further explained.
Campbell Thompson himself, in a brief published reference to BM 96577 in his 1924 article in the Journal of the Royal Asiatic Society described the tablets anatomical content as of theological rather than medical character and indicated that he intended to publish a full analysis in a forthcoming monograph on Babylonian medical literature.
The monograph appeared in 1928. The full analysis of BM 96577 was not in it. Campbell Thompson continued to publish prolifically on Babylonian topics for another two decades, but the promised analysis was never completed. His private correspondence from the late 1920s contains brief references to the duplicated organ passage that he had been working on with notes indicating that he had encountered interpretive difficulties that he expected to resolve later.
He did not resolve them publicly. Now, the modern stakes and the demands of the genre are clear. The question that BM 96577 and the corroborating cross-cultural texts raise is not just whether the Sumerian scribes had access to information about human embryology that they could not have obtained through ordinary observation.
The question is whether the information they preserve goes beyond what modern medicine has so far confirmed. The fact of embryonic cardiac fusion is well established. What is less well established is what, if anything, remains as a functional vestige of the original two-heart configuration in the adult human body.
The standard cardiology textbook position is that nothing remains. The fusion is complete and the resulting single organ is the heart in every meaningful sense. But there are observations that complicate this picture and they have been accumulating over the past several decades. The human heart possesses an unusually elaborate intrinsic nervous system, sometimes called the heart brain, or the intrinsic cardiac nervous system.
This network of approximately 40,000 neurons embedded in the heart tissue is capable of independent processing, and it influences cardiac rhythm in ways that the standard pacemaker model does not fully capture. The heart also produces its own hormones, including atrial natriuretic peptide, and engages in two-way signaling with the brain through the vagus nerve and through circulating chemical messengers.
The picture that emerges from modern cardiology research is of an organ that is substantially more intrinsic neural and endocrine capability than the textbook description suggests. Research by Andrew Armour and others over the past three decades has documented that the intrinsic cardiac nervous system can learn, remember, and make decisions independently of input from the brain.
The system has its own short-term memory. It modulates heart rate in response to factors that the central nervous system does not directly observe. It has been described in cautious published accounts as a little brain with capabilities that exceed what would be expected of a simple peripheral ganglion. The HeartMath Institute has published research extending these findings into the domain of electromagnetic field interaction between hearts of different individuals, though that work is more contested than the core neurocardiological research.
Separately, the human body contains what neuroscientists now refer to as the enteric nervous system, a network of approximately 500 million neurons distributed throughout the gut, capable of independent processing, and connected to the brain through the vagus nerve. This system is sometimes called the second brain in popular accounts, and the comparison is not entirely metaphorical.
The enteric nervous system can function autonomously, produces most of the body’s serotonin, and influences mood, cognition, and many physiological processes in ways that conventional medicine has only recently begun to integrate. The two hearts description on BM 96577 does not specify where the second heart was located.
The damage to the tablet’s reverse side prevents reconstruction of the relevant detail. What survives is the statement that two organs existed, that one was removed, and that the present human body retains traces of the original configuration. Whether those traces correspond to the intrinsic cardiac nervous system, to the enteric nervous system, to the thymus gland, or to some other structure that modern medicine has not yet adequately characterized, is on the evidence available an open question.
The genre’s required concession. BM 96577 is most plausibly read as a religious medical text whose use of anatomical language is theological rather than literally embryological. The Sumerian and Babylonian medical tradition produced extensive observations, but it did not have access to systematic embryology, and any apparent correspondence between the scribe’s description and modern developmental biology can be explained through the combination of empirical observation, specifically the documented
occurrence of cardia bifida in stillborn fetuses, and the inherent likelihood that any sufficiently detailed ancient anatomical text will eventually correspond to some piece of modern medicine by chance. The cross-cultural parallels in Egyptian, Indian, and Chinese sources are real, but explainable through the universal tendency of ancient medical traditions to identify candidate second hearts among the various organs visible at autopsy and dissection.
The access restrictions on BM 96577 are most plausibly explained by ordinary conservation concerns. Campbell Thompson’s failure to publish the full analysis is most plausibly explained by competing research priorities rather than by suppression. This is the responsible position. It is probably correct. What is harder to dismiss is the specificity of the language.
The verb lu on BM 96577, meaning extraction or excision, is not used elsewhere in the Babylonian medical literature for natural developmental processes. It is used for surgical and divine actions. The scribe was not describing fusion or reduction by absorption. He was describing the deliberate removal of an organ that had existed and now did not.
This is closer, structurally, to what one might describe if one had observed cardia bifida in a stillborn fetus and had developed a theological framework in which the failure of one of the two hearts to survive, its apparent excision during development, was identified as the explanation for the normal single heart adult condition.
The scribe was describing a deliberate event. The Babylonian medical tradition documented cardia bifida directly. They knew the condition existed. They may have built their understanding of normal cardiac development around the observation of abnormal cases. Each individual element has an alternative explanation.
The overall pattern is harder. The tablet sits in London. The Campbell Thompson notebook gap is in its 100th year. The access restrictions are in their 17th year. The intrinsic cardiac nervous system continues to be characterized by cardiology researchers with new findings appearing in the literature at an accelerating rate.
The enteric nervous system is now widely recognized as a substantial neural network with autonomous capabilities. Heart transplant recipients have, in numerous documented cases, reported experiences that the standard physiological model does not fully account for. Taste preferences, emotional dispositions, and in some cases memories that appear to be associated with the donor rather than the recipient.
The phenomenon is contested. The data are real. They have not been satisfactorily explained. Paul Pearsall, a clinical neuropsychologist who collected and analyzed dozens of heart transplant case reports in the 1990s, documented numerous instances in which recipients reported specific knowledge, preferences, or experiences that they could not have known, and that turned out to correspond to traits of the donor.
The mainstream medical position is that these reports are anecdotal and explainable through coincidence, suggestion, or the psychological effects of major surgery. The reports themselves continue to accumulate, and several research groups have called for systematic investigation that has not yet been adequately funded.
The Sumerian scribe at Nineveh wrote 4,000 years ago that the original human form had two hearts, and that the removal of one of them is what made us what we are. Modern embryology has confirmed that every human body does in fact begin with two hearts, and that the fusion of these two into one is a normal developmental event.
Whether what was lost in that fusion is anything that modern medicine has yet characterized, or whether the description is purely theological, depends on how you read the convergence between what the scribe wrote and what the embryologists have found. There is one final detail. BM 96577 ends with a phrase that Campbell Thompson rendered in his unpublished 1924 working notes, as in where there was the second, now there is silence.
The phrase has been disputed. The Sumerian word translated as silence, c.e.l., can also mean an absence that listens or a quiet that remains. A more aggressive reading proposed by an independent researcher in 2017 and ignored by mainstream scholarship translates the phrase as in where there was the second there is now a hearing that does not speak.
The grammar admits both readings. The scribe was specifying that something remained where the second heart had been, something that could perceive but not articulate, something that the body still contained but in altered form. Silence is one possible reading. What that residual structure is the scribe at Nineveh did not say.
He may have meant the soul. He may have meant the thymus gland. He may have meant some category of physiological reality that the Babylonian medical tradition could distinguish but for which we no longer have a clear term. The tablet does not specify. What it specifies is that something is still there in the place where the second heart used to be and that what is there has the quality of perception without expression.
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