Ibn an-Nafis and Pulmonary Circulation

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Ibn an-Nafis and Pulmonary Circulation

Overview

During the thirteenth century, the Egyptian physician Ibn an-Nafis (c. 1210-1280; also known as Ali ibn Abi al-Harma al-Qurayshi Ibn an-Nafis) described the minor, or pulmonary circulation of the blood. However, this discovery was apparently ignored by his contemporaries and was forgotten until the twentieth century. Historians of medicine generally believed that pulmonary circulation was first described by Miguel Serveto (Michael Servetus; c.1511-1553) and Realdo Colombo (c. 1516-c. 1559) in the sixteenth century.

Background

The Middle Ages of European history roughly correspond to the golden age of Islam, the religion founded by the prophet Muhammad (570-632). Just as Latin served as the common language of learning for students throughout Europe, Arabic was the language of learning throughout the Islamic world. Thus, Arabic texts need not have Arab authors; Persians, Jews, and Christians took part in the development of Arabic scientific literature. From the ninth to the thirteenth century Arab scholars could justly claim that the world of scholarship had been captured by Islam. Scholars at ancient centers of learning were encouraged to assist in the immense task of translating ancient manuscripts into Arabic. Pharmacology, optics, chemistry, alchemy, and medicine were of particular interest to Islamic scholars.

Until about the second half of the twentieth century, European historians generally looked at so-called Arabian science, medicine, and philosophy in terms of a single question: were the Arabs merely the transmitters of Greek achievements or did they make any original contributions? Eventually, historians rejected this approach and concluded that this question was inappropriate when applied to a period in which the very idea of a quest for new secular knowledge was virtually unknown. Medieval physicians, philosophers, and scientists accepted the writings of the ancients as essentially true and authoritative. Their goal was to preserve, analyze, and clarify the writings of the ancient. Nevertheless, Arabic translators, physicians, and philosophers eventually absorbed, assimilated, and transformed the writings, ideas, and theories of the ancient Greeks. The work of the Greek physician Galen (c. 130-c. 200) was especially revered and medieval physicians and scholars, whether Muslims, Jews, or Christians, generally shared the assumption that Galenism was a complete and perfect system.

The writings of Islamic physicians and philosophers, which were often presented as commentaries on the work of Galen, were eventually translated from Arabic into Latin and served as fundamental texts in European universities for hundreds of years. But for many European scholars medieval Arabic writers were significant only in terms of the role they played in preserving Greek philosophy during the European Dark Ages.

Much about the history of science and medicine, however, has been revealed through attempts to study the work of Islamic writers on their own terms. Western scholars assumed that the major historical contribution of Islamic medicine was the preservation of ancient Greek wisdom and that medieval Arabic writers produced nothing original. In the West, during the late Middle Ages and the Renaissance, the Arabic manuscripts that were sought out for translation into Latin were those that most closely followed the Greek originals. Arabic manuscripts that criticized Galen, or introduced novel ideas were dismissed as corruptions of ancient Greek wisdom. Therefore, the original premise of European scholars, that medieval Arabic scholarship lacked originality, was confirmed.

Impact

The story of the thirteenth century Egyptian physician Ibn an-Nafis and his discovery of pulmonary circulation demonstrates the unsoundness of previous assumptions about medieval Arabic literature. The writings of Ibn an-Nafis were essentially ignored until they came to the attention of twentieth century science historians. Ibn an-Nafis is now regarded as the first physician to recognize the minor, or pulmonary, circulation of the blood, that is, the movement of blood between the heart and the lungs.

Contemporaries honored Ibn an-Nafis as a learned physician, ingenious investigator, and prolific writer. According to one biographical sketch, he completed a treatise on the pulse between ablutions at the public bath. In addition to a commentary on Avicenna's (Ibn Sina; 980-1037) Canon, Ibn an-Nafis had plans for a comprehensive 100-volume compendium of medicine. About 30 volumes were apparently completed when he died, but only a few survived. While serving as chief of physicians in Egypt, Ibn an-Nafis became seriously ill. Other physicians urged him to take wine as a medicine, but he refused for reasons of piety. He told his colleagues that he did not wish to meet his creator with alcohol in his body.

It is not clear how Ibn an-Nafis actually discovered pulmonary circulation. Human dissection was generally prohibited by Islamic law and custom and a man as pious as Ibn an-Nafis was unlikely to challenge such laws. In his writings, Ibn an-Nafis frequently invoked religious law to explain why he did not perform dissections. Indeed, in his Commentary on the Anatomy of Avicenna, Ibn an-Nafis explained that he could not practice human dissection because of the prohibitions of religious law and his own natural charity. Systematic human dissection was not acceptable in the Muslim world, because orthodox Muslims believed that mutilation of a cadaver was an insult to human dignity. Islamic law forbids the practice of the kinds of ritual mutilation that had apparently followed warfare in ancient times. Muslim legal experts argued that scientific dissection was essentially the same kind of violation of the human body. However, some anatomical research was conducted on various animals, such as monkeys and sheep. Despite his reluctance to perform dissections, Ibn an-Nafis was eventually led to question Galenic physiology.

As was customary, an-Nafis began his account of the structure and function of the heart with a fairly conventional reflection on traditional theories. However, after finding inconsistencies in Galen's account of the functions of the lungs, heart, and associated vessels, an-Nafis went on to propose a novel theory of the movement of the blood between the heart and the lungs. Rejecting the usual belief that Galen was virtually infallible, an-Nafis expressed his criticism of traditional Galenic physiology and insisted that there were no visible or invisible passages between the two ventricles of the heart. Moreover, he argued that the septum between the two ventricles was thicker than other parts of the heart. The thick-walled septum would, therefore, prevent the harmful and inappropriate passage of blood or spirit between the right and left parts of the heart. This position was actually stronger than that taken by the sixteenth century European anatomists, because Ibn an-Nafis rejected the possibility of invisible, as well as visible, pores in the septum of the heart. To account for the presence of blood in both sides of the heart, Ibn an-Nafis argued that after the blood had been refined in the right ventricle, it must be transmitted to the lungs where it was rarefied and mixed with air. The finest part of this blood was then clarified and transmitted from the lung to the left ventricle. In other words, the blood must move in a circle between the heart and the lungs because the blood could only get into the left ventricle by way of the lungs.

The writings of Ibn an-Nafis were essentially ignored until 1924 when Dr. M. Tatawi, an Egyptian physician, presented his doctoral thesis to the medical faculty of Freiburg. Fortunately a copy of Tatawi's thesis came to the attention of professor Max Meyerhof, an eminent historian of medicine who recognized the significance of the long-neglected writings of Ibn an-Nafis. Without the attention of Tatawi and Meyerhof, the first account of pulmonary circulation might have been forgotten again.

There is no direct evidence that Ibn an-Nafis could have influenced later writers, but the fact that he was able to describe his theory so clearly in the thirteenth century provides an interesting challenge to previous assumptions about progress and originality in the history of science. Since only a small percentage of Arabic manuscripts from this period have been studied, edited, translated, and printed, the possibility remains that some other medieval manuscript could contain a commentary on the unorthodox theory of Ibn an-Nafis.

Since World War II, scholars have examined many Arabic manuscripts that were previously unknown, ignored, or unpublished. This has changed the way historians of science and medicine and other students of Islamic studies view the development of Islamic science. Although scholars generally agree that a decline in Islamic science and medicine did occur after its socalled golden age, it occurred later than the eleventh century, which was previously considered part of the period of decline, and might be placed as late as the fifteenth or sixteenth century. New studies of Arabic manuscripts reveal that between the twelfth and thirteenth centuries, for example, important work in astronomy, mathematics, optics, pharmacology, and medicine was conducted. The research on Ibn an-Nafis is a prominent example of this scholarship. Some historians believe that hundreds, or even thousands, of manuscripts written between 500 and 1,000 years ago are still gathering dust in various archives throughout the world. Further studies of such manuscripts might clarify ambiguous aspects of Islamic scholarship and might lead to new discoveries.

LOIS N. MAGNER