The Heart in the Library

In the regional museum of Detmold, Germany, lies the mummy of a baby. Where it came from is uncertain: it is thought to be from South America. Radiocarbon dating places the child at about 4500 BCE, and the teeth suggest an age of six months at death.

In 2015 cardiologists and radiologists from the Heart and Diabetes Centre in Bad Oeynhausen passed the small body through a CT scanner and found that the left side of the heart had never grown. Hypoplastic left heart syndrome usually kills within weeks of birth, once the ductus arteriosus, a vessel that bypasses the lungs before birth, closes and the body loses its blood supply; today prostaglandins keep the duct open until a surgeon can intervene.

How this child lived for six months is unknown. The authors raised a possibility, not a finding: at high altitude the duct often closes late, and that may have bought the child time. Since the child's origin is itself uncertain, the explanation remains a guess.

Modern medicine reached that diagnosis the way it examines most patients, one competence at a time: engineers built the scanner, radiologists read it and paediatric cardiologists recognised the defect. This series follows that division of labour, mostly through the heart: who asked the questions, who could read what others had already found, and how medicine learned to ask for evidence instead of deferring to authority.

For more than a thousand years physicians followed Galen, the Greek physician of the second century, who taught that blood seeped from the right ventricle to the left through invisible pores in the septum. Avicenna's Canon of Medicine repeated the claim, and generations of commentators explained it.

Ibn al-Nafis, born in Damascus in 1213, trained at the hospital there and moved to Cairo at 23, where he became physician-in-chief of the Al-Mansouri Hospital. At 29 he wrote a commentary on the anatomy of the Canon. The septum, he stated, is solid and has no passage, visible or invisible: all the blood that reaches the left ventricle must first pass through the lungs, by small communications between the pulmonary artery and the pulmonary vein, a prediction made about 400 years before Marcello Malpighi saw the capillaries.

Where the Detmold diagnosis needed a team, Ibn al-Nafis held several fields in one head. He wrote on law, theology, philosophy and astronomy, and an early Arabic novel about a child raised alone on a desert island. The historian Nahyan Fancy has shown that commentaries like his tested each received claim by argument and at times by observation, and that his was widely cited in the Islamic world.

Europe did not read it. A Latin translation of 1547 rendered a different work of his, on compound drugs. Michael Servetus in 1552 and the anatomist Realdo Colombo in 1559 described the passage of blood through the lungs, each apparently by his own route, and many historians believe that Servetus never knew of the physician in Cairo. Neither grasped the larger circuit, which William Harvey published in 1628.

The commentary reached Western readers in 1924, when a young Egyptian physician, Muhyo al-Deen el-Tatawi, came across the manuscript in the Prussian State Library in Berlin while writing his doctoral thesis for the University of Freiburg. By then European anatomy had reached the same conclusion by other routes, more than three centuries earlier. Whether an earlier reading in Padua or Paris would have changed anything is a question the surviving record cannot answer.

Last updated: 22 October 2026