This is What Early Muslim Physicians Said About the Science of Laughter

The Muslim thinkers of the Middle Ages seem to have offered some commentary on just about anything you can think of, and ‘Laughing Out Loud’ is no exception. Here’s what some of them had to say about that.

In the mid-9th century, the physician Ali ibn Rabban at-Tabari explained laughter in this way: “Laughter is the [result of] the boiling of the natural blood [which happens] when a human being sees or hears something that diverts him and thus startles and moves him. If he then does not employ his ability to think in connection with it, he is seized by laughter.” In other words, according to Ibn Rabban, laughter is the result of a person’s inability to think rationally about something that they are suddenly exposed to. After this passage, he shared Aristotle’s definition of the human as the laughing animal, followed by the Greek philosopher’s observation that out of all the animals, only humans can laugh.

The famous Muslim polymath Abu Yusuf al-Kindi, who also lived in the mid-9th century, commented on laughter in similar terms. He defined it as “an even-tempered purity of the blood of the heart together with an expansion of the soul to a point where its joy becomes visible”.

Ishaq ibn Imran was a thinker coming later in the 9th century, and his thoughts on laughter were similar but more detailed. In his book ‘On Melancholy’, he described the laughter of children and drunk people as the result of “the joy of the soul because of the even temper of their blood”. He also described excessive laughter as a sign of insanity. He then commented on laughter in more detail, defining it as “the astonishment of the soul at [observing] that is not in a position to understand clearly” and discussing different theories on where it originates in the body. In the 11th century, Constantinus Africanus translated On Melancholy from Arabic to Latin. Africanus’ Latin collection of textbooks (including Ibn Imran’s work) was translated into other European vernaculars and used until the 17th century.

A famous student of Ibn Imran was the physician Ishaq ibn Sulayman. He suggested that sadness is caused by anything restricting the flow of blood in the body and the release of heat from it. Therefore, laugher and joy are caused by healthy circulation of the blood and a working exothermic process in the body. It’s interesting that Ibn Sulayman developed his own theory about laughter rather than just borrowing from his teacher, Ibn Imran. Some of Ibn Sulayman’s work was translated into French in 1579 by a man named Joubert, who suggested that Ibn Sulayman was the first to offer a definition of laughter – and then discussed how wrong it was and why his own definitions were better.  

There are two important points to note here. The first is that these early Muslim thinkers didn’t take anything for granted, not even something as seemingly trivial as laughter. They did their research and tried to describe the origins and characteristics of laughter. The second is that they all recognized that laughter has something to do with the circulation of blood in the body. More than a thousand years later, science has established that laughter does, in fact, lower blood pressure and improves blood flow. The lesson? Don’t settle for a shallow understanding of anything, and never forget to LOL!  

Source: Franz Rosenthal, Humor in Early Islam (Leiden: Brill, 1956), 132-138.

Written by Hassam Munir

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Hassam Munir is a student and independent researcher of Islamic history based in Toronto, Canada. He enjoys looking into the past from fresh and diverse perspectives. He is the founder of the iHistory project, where he blogs regularly. To read more of Hassam's work on Islamic history, visit