Human progress has seen major setbacks in the past due to many reasons. Inventions such as that of flexible glass, if accepted when it was introduced to the world, would have changed the face of humanity forever. But the interfering of one person has brought drastic change for humanity. Here are 10 people who single-handedly damaged the progress of humanity.

1 Guy de Chauliac 

The surgeon, Guy de Chuliac, spoke vehemently against Theodoric Borgognoni who taught the proper way of wound care is to clean it and wrap it up. Guy hated that this new teaching went against ancient Greek surgeon Galen. His teachings were widely accepted which led to ignorance in developing the antisepsis method for 600 years, which would have had a huge impact on human progress. 

Chuliac was the most celebrated surgeon during the European middle ages. His work was the standard in surgery up until the 17th century. He strictly followed the ancient Greek surgeon Galen’s methods of surgery.

Even though Galen was a pioneer in dissection and surgery, his methods were sometimes outdated by 7,500 years. He remained unquestioned for years as the findings linked with religion. 

Being a follower of Galen, as the other surgeons at the time, Guy de Chauliac, who had a lot of influence as a surgeon, was against the teachings of a barber-surgeon named Theodoric. At the time, soldiers who were wounded were treated by putting boiled oil on the wound.

Theodoric, who was in the field working with wounded soldiers for a long time, found out cleaning the wound and tying it up tight would help much better.

Since people believed surgeons with traditional training at the time should be the only ones to be believed even though the barber-surgeons had more experience dealing with the wounded. This led to many more years of suffering for wounded soldiers and many deaths. (Source)

2 Tiberius Caesar 

The inventor of flexible glass was executed by Tiberius Caesar according to Petronius who was a Roman Courtier at the time. The Roman emperor of that time did this because he feared glass would become more valuable than gold and silver if this invention came out. 

Flexible glass is a lost invention from the time of the Roman Empire around 14 BCE. The inventor brought a bowl made of flexible glass before Caesar. The bowl was tested in front of him.

They tried to break it but it only dented. The inventor repaired the bowl with just a hammer. Tiberius had the man executed after he swore he was the only one who knew the technique.

According to Petronius who was Caesar’s confidant at the time, he was worried that flexible glass will become more valuable than gold and silver.

Eventually, apart from the accounts of two compilers who talked about this invention, flexible glass found its way back later and is now used in an optical fiber which is now helping humans immensely. (1, 2)

3 Thomas Midgley, Jr.

This chemical engineer who invented leaded gasoline and chlorofluorocarbons (CFC) has held hundreds of patents. His legacy is seen more negatively because of the impact it had on the environment. A historian remarked that this human “had more impact on the atmosphere than any other single organism in the Earth’s history.”

Midgley, in December of 1921, came across some tetraethyl lead. After this finding, the big companies chose to hide using the word “lead” to safeguard them from being associated with this.

But slowly people working in the ethyl plants began suffering from lead poisoning. The inventor himself briefly suffered from the same.

Eventually, he ended up making a freon that cooled indoor air for half a century. In 1922, the US Public Health Service warned about the dangers of leaded fuel and lead production.

The World Bank finally banned investments in leaded gasoline in 1996 followed by the European Union in 2000. An estimate of seven million tons of leaded gasoline has been released into the atmosphere from the US alone. (Source)

4 Bayezid II 

Despite knowing about printing presses as early as the 1480s, the Ottoman Empire did not permit the printing of Arabic scripts until 1727. They were restricted from printing any Islamic works or Arabic script as decreed by Bayezid II. This was later renewed by his son in 1515 and made it punishable by death.

The printing ban by the Ottoman Empire is attributed to their bigotry against human progress.

Even though Turks enjoyed the aesthetics of elegant handwriting and liked when the ink shined on their books, the real side of the myth as explained by historians is that the empire hindered the printing presses by saying that it is a sin and it was invented by the infidels.

The rulers banned printing religious books and loosened the complete ban later in the 1700s. After 1727, when the Ottoman industrial revolution began, the first printing press that belonged to Muslims was opened. That was 36 years after the first printing press opened in New York. (Source)

5 Bakhtiyar Khilji 

Bakhtiyar Khilji was a Turkish invader who burnt the Nalanda University in 1202 BCE. He was shocked by the fact that Indian scholars and teachers had more knowledge than his countryman. He set fire to the library of Nalanda and burned nine million manuscripts. 

Bakhtiyar Khilji ruled some areas of north India when he fell sick. He was told that the Ayurveda Department of Nalanda University was a good place for treatment. He was not willing to believe that Indian physicians had more knowledge than his masters. 

To save his life, he approached Acharya who was the head of the Ayurveda Department of Nalanda University. He put a strange condition on the doctors saying that he would take no medicine. They took up the challenge of fixing his sickness without medication. 

The doctor brought him a Quran and advised him to read certain pages. Eventually, Khilji was cured. The doctor later revealed that he applied suggestions on the pages and he got cured as he read the Quran. He was surprised by how they did it. He decided to destroy the roots of Buddhism and Ayurveda which lead to the burning. (Source)