A guy posted a tweet about a mural on a medical building that shows someone who presumably represents medicine fending off death, while holding a staff with wings at the top and two snakes wrapped around it. Pretty normal, right? Except that the staff with wings and two snakes has nothing to do with medicine at all — it’s called a “caduceus” and it’s associated with Hermes the messenger (or Mercury, if you are Roman instead of Greek), who is associated with commerce and other things. What this medical god should be holding is the rod of Asclepius, which has no wings and only one snake.
Despite this, lots of medical iconography, especially in the US, uses the caduceus instead of the rod of Asclepius. The US Marine Service started using it in 1857, and in 1902, it came to represent the US Army Medical Service and the US Public Health Service, which adopted it in 1881. Why did they choose the wrong one? Probably because it looks more impressive. After all, it’s got wings. And two snakes instead of just one. Way cooler 🙂
There are also theories that the two-snake rod became popular as a symbol representing medicine because early medications used mercury, and from there it became associated with pharmaceutical side of medicine, and then later was used to represent all of medicine. But some medical professionals don’t like to use the two-snake staff because it is primarily associated with commerce, rather than with the healing arts in general.