18 February 2021

Francesco Redi - biologist and poet

Renaissance scholar who debunked scientific myths

Francesco Redi proved that maggots resulted from flies' eggs
Francesco Redi proved that maggots
resulted from flies' eggs
The physician Francesco Redi, famous for challenging a centuries old belief that certain living things arose through spontaneous generation rather than any reproductive process involving parent organisms, was born on this day in 1626 in Arezzo, Tuscany.

Redi, who enjoyed literary success alongside his work in experimental biology, devoted much of his scientific life to dismantling some of the widely held beliefs in his field that he was sure were incorrect.

The most famous of these was that the maggots frequently discovered in rotting meat occurred spontaneously as a product of the decaying flesh.

In order to show that this was a myth, Redi conducted a number of experiments in 1668 involving sets of jars containing dead fish and raw pieces of different meats. In the first, he sealed three of six jars and left the other three open. In the second, he placed raw meat in three jars, plugging one with a cork stopper, placing gauze over the other and leaving the third open.

After a period of time, the flesh in the open jars contained maggots, but in the sealed jars did not.  In the gauze-covered jar, maggots appeared on the surface of the gauze but not in the meat.

The cover of Redi's book about the generation of insects
The cover of Redi's book about
the generation of insects

Redi’s belief was that maggots came from tiny eggs laid by flies on the surface of the rotting meat or fish. To add further weight to his theory, he captured some live maggots, which then metamorphosed into flies.

In a further experiment, he placed dead flies in one jar containing meat and live flies in another. Only in the jar with live flies did maggots appear in the meat.

These experiments were described in Redi’s magnum opus, Esperienze intorno alla generazione degl'insetti (Experiments on the Generation of Insects).

This is generally recognised as the first refutation of spontaneous generation, the belief in which went back at least 2,000 years to the time of the Greek philosopher Aristotle and possibly beyond. It was not entirely disproved until the mid-19th century. Redi’s work with maggots was also one of the first recorded examples of a scientific experiment using controls, which would later be recognised as an essential element of biological research. 

Earlier, Redi’s 1664 work Osservazioni intorno alle vipere (Observations on vipers) challenged some bizarre suppositions relating to vipers, which were thought for many years not only to be capable of shattering glasses but drinking wine.

Redi proved that the venom of the snake, which was thought to be harmful when swallowed, came not from the reptile’s gallbladder but was contained in fangs in the mouth and poisoned its victims by entering their bloodstream via a bite. He also showed that by tightening a ligature around a bitten limb, the venom could be prevented from reaching the victim’s heart.

Detail from the funeral monument to Redi in Arezzo's duomo
Detail from the funeral monument
to Redi in Arezzo's duomo
As well as debunking myths, Redi also carried out considerable research in his major area of interest, parasitology.  His books on the subject described 180 species of parasites that he had identified.

Redi, whose father was an eminent physician, obtained degrees in medicine and philosophy at the University of Pisa. His career took him to Rome, Naples, Bologna, Padua and Venice before he settled in Florence, where he served at the Medici Court as both the head physician and superintendent of the ducal apothecary to Ferdinando II de' Medici, Grand Duke of Tuscany and his successor, Cosimo III

His major contribution to Italian literature was a collection of his poems published in 1685 called Bacco in Toscana (Bacchus in Tuscany), which he wrote in praise of Tuscan wine and is considered one of the finest works of 17th-century Italian poetry, and which prompted Cosimo III to award Redi a medal of honour.

Redi died in Pisa in 1697 at the age of 71. His remains were taken to Arezzo, where there is a funeral monument to him on the wall of the left nave of the city’s duomo, the Cattedrale di Ss. Donato e Pietro.

Science commemorated his life in several ways, including a crater on Mars named in his honour. The Redi Award has been given annually by the International Society on Toxinology since 1967, a scientific journal called Redia, an Italian journal of zoology first published in 1903, was named after him, as is a European viper subspecies, vipera aspis francisciredi.

Arezzo's sloping Piazza Grande is regarded as one of the most beautiful squares in Tuscany
Arezzo's sloping Piazza Grande is regarded as one
of the most beautiful squares in Tuscany
Travel tip:

Arezzo, the city of Redi’s birth, is one of the wealthiest cities in Tuscany. Situated at the confluence of four valleys - Tiberina, Casentino, Valdarno and Valdichiana – its medieval centre suffered massive damage during the Second World War but still has enough monuments, churches and museums to be a worthwhile stopover on tourist itineraries. Its main sights include the Basilica di San Francesco, with its beautiful frescoes by Piero della Francesca, the central Piazza Grande, with its sloping pavement in red brick, the Medici Fortress, the duomo and a Roman amphitheatre.

Arezzo's cathedral stands in an elevated location a short distance from the city centre
Arezzo's cathedral stands in an elevated location
a short distance from the city centre
Travel tip:

Arezzo’s original cathedral was built on the nearby Pionta Hill, over the burial place of Donatus of Arezzo, who was martyred in 363. In 1203 Pope Innocent III had the cathedral moved within the city's walls, to the current site in another elevated position a short walk from Piazza Grande.  The construction of the current structure started in 1278 and continued in phases until 1511, although the fa├žade visible today, designed by Dante Viviani was not completed until 1914, replacing one left unfinished in the 15th century.  The interior contains several notable artworks, including a relief by Donatello, entitled Baptism of Christ, and a cenotaph to Guido Tarlati, lord of Arezzo until 1327, said to be designed by Giotto, near to which is Piero della Francesca's Mary Magdalene.  The wooden choir of the Grand Chapel was designed by Giorgio Vasari.

Also on this day:

1455: The death of early Renaissance painter Fra Angelico

1564: The death of painter and sculptor Michelangelo

1967: The birth of football icon Roberto Baggio

1983: The birth of tennis star Roberta Vinci

(Picture credits: Funeral monument by Stefano Bolognini via Wikinedia Commons; Piazza Grande, Arezzo by El_en_a from Pixabay; Arezzo cathedral by Spike)


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