Modern medicine owes its successes to centuries of trial-and-error experiments on the human body. Without accidental discoveries and meaningful mistakes, our medical canon wouldn't be as full as it is today.
Here are a few of the grisly practices that led to the efficient methods we have today.
SEE ALSO: See startling photos of brain surgery's earliest patients
Doctors drilled holes in patients' skulls to cure neurological problems.
Trepanning, as the practice is called, is one of the oldest surgical practices in the archaeological record. Skulls with holes have been found dating back to the Neolithic period, according to a study in Surgical Neurology International.
The procedure was usually done on people who were acting abnormally. The belief was that drilling a hole into someone's head until the surface of the brain tissue showed could cure them of seizures or mental disorders.
According to Mental Floss, French neurologist Paul Broca suggested in the 1870s that the procedure had been done by ancient cultures to keep bad spirits from being trapped in the brain. But archaeologist Ephraim George Squier, who worked with Broca, suggested people trepanned to relieve swelling and pressure buildup in the skull after head injuries.
Today, the practice of trepanning still exists among brain surgeons, albeit not by the same name. They call it craniotomy, and it's used to relieve pressure in the skull and implant brain stimulators in Parkinson's patients.
Cupping, which is now popular with Olympic athletes, dates back to China's Han Dynasty.
Cupping was being practiced long before the 2016 Summer Olympics. Records date the practice, which supposedly promotes blood circulation, back to the Han Dynasty (221-206 BC).
The technique involves placing a heated cup on targeted areas of the body and inducing suction by cooling the cup or mechanically pumping out air. The cup is left on for five to 15 minutes, then taken off, leaving a visible mark that eventually fades away.
There are two ways to do cupping: dry cupping and wet cupping. The major difference between the two is that wet cupping involves small incisions on the skin to let blood flow during the process.
Leech therapy goes back to the ancient Greeks and Indians.
These bloodsucking worms might be the stuff of nightmares, but for a time, they were used unflinchingly in medicine.
The practice was referred to as "blood letting" in the ancient Indian text Sushruta Samhita and was also used in ancient Greek and Roman medicine.
The belief was that bodily fluids had to be in balance to be healthy; imbalances were considered the cause of inflammation, fever, or diseases that made skin appear redder than usual.
Leech saliva reportedly has anesthetic properties, which is why a leech can go unnoticed and is the reason the medical procedures were virtually painless for patients.
Today, leech therapy has found its way into alternative medicine, where it's been used in microsurgery and as a procedure to cure anything from migraines to varicose veins.
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