Times might be tough in the world right now, but you should always be happy that you live today and not thousands of years ago. You know, back when medicine was virtually indistinguishable from torture. I recently reported on horrifying ancient medical practices like brutal Neanderthal dentistry. Now we’ve learned that doctors during China’s Ming Dynasty were apparently knocking patients out for surgery using poison.

According to a new study published in the journal Antiquity, researchers discovered the first direct chemical evidence of anesthetic residue on 600-year-old surgical tools found in a Chinese tomb.

The tools belonged to Xia Quan, a Ming Dynasty surgeon whose grave was excavated in the 1970s in Jiangyin County, China. The rusty iron scissors and tweezers sat around for several decades before modern researchers decided to analyze the reddish residue covering the tools using laser-based spectroscopy. They found traces of something called aconitine, a toxic compound derived from Chinese wolfsbane.

Scientists Found Evidence That Ancient Surgeons Used Poison to Knock Patients Out

It’s easy to imagine ancient doctors unknowingly misusing a toxic compound as some kind of medicine in itself. That’s not the case here. Researchers say that the Ming Dynasty docs absolutely knew that it was a very dangerous poison. Historical texts show that they developed methods to detoxify it using a range of common acidic edible substances, like vinegar, mung beans, or the urine of young boys, which I imagine is technically edible, though you very much shouldn’t consider it so.

Whatever their substance of choice was, they applied it to the skin as a topical anesthetic before minor surgeries. The researchers think the surgeons would numb the area first, then use tweezers to hold the skin while scissors excise damaged tissue or surface growths. The toxic residue was concentrated around the working ends of the tools, meaning that the anesthetic was actively used during procedures.

While this might seem like a laughable mistake made by ancient stupid people, it actually demonstrates an incredible, nuanced understanding of a dangerous substance. Ming Dynasty-era doctors understood that, when handled properly, small controlled doses of a literal poison could be used to our benefit, and they were doing it centuries before administering anesthesia became a whole, highly lucrative career unto itself.