The thumbs-up is a symbol that most of us have known our entire lives. It’s become synonymous with positivity, congratulations, a job well done, and with online school, it has found even more use in everyday conversation. However, despite the seeming simplicity of it, the roots of it go back centuries!

The idea of using a thumb pointed upwards or down first found meaning in Ancient Roman gladiator fights. These brutal fights are often depicted in Hollywood action films to be barbaric and somewhat disturbing, but actually were built around a somewhat fair set of rules that aimed at entertaining a crowd, and not always ending in blood-soaked arenas. In fact, they even had their own form of a referee, called a summa rudis. This ancient ref would monitor the battle and decide when it was over. When it was time for the fight to conclude, he would flash one of a large variety of hand signals to both the gladiators on the ground and the crowd watching. One such signal was the thumbs up; unfortunately for the gladiator, this was the rudis calling for him to be killed.

Two millennia later, the motion would adopt its more positive meaning. First World War veteran Arthur Guy Empey, who was American but served in the British Army, recounted his experiences in battle in his 1917 book “Over The Top.” It was here that he mentioned how other soldiers in the U.S. Army would flip up a thumb to indicate that everything was fine. Their British counterparts gave the gesture the name the “thumbs-up.” Similarly, pilots in World War II used it as a quicker and more efficient way of telling their flight crew that they were safely strapped into their aircraft.

Usage expanded into more non-military communities with the popularity of the classic ‘70s and ‘80s show “Happy Days,” in which Fonzie was famous for using the gesture.

The trend continued. In 2007, advanced teams on the ever-growing social media site Facebook were looking for a way to keep the platform fresh, and working on things called “props,” actions to interact with posts. They debated stars, rating systems, and even used the working name of the “awesome button.” But after much debate, and a little input from CEO Mark Zuckerberg himself, they came up with one of the most influential tools of the 21st Century: the “like” button. And the symbol chosen to portray this? A thumbs up, of course.

By this point in history, there is no doubt what a thumb pointed to the skies indicates. It has become even more important in an age of masks and digital school, in which so much of our expression through body language is lost. Unmuting is a glitch-plagued hassle which can lead to more confusion. A teacher checking for understanding may instead see a screen filled with thumbs up. 

Hundreds of years have passed since the sign was first used, and the meaning has been altered back and back again and back once more. Yet the usage is consistent, and for the same reasons. So the next time you respond to a teacher with the thumbs up, think of a summa rudis doing the same; think of a soldier preparing for battle; think of a World War II era pilot signalling his flight crew; and think of the long history behind a simple movement.