Researchers say the numbing agent splashed onto iron scissors and tweezers during a procedure. They were found in a Ming dynasty doctor’s tomb The instruments and close-ups of their residues Antiquity In the early 15th century C.E., a doctor in China was entombed with surgical instruments. Recent analysis of residues left on those tools found that they’re coated in traces of a poisonous topical anesthetic—now the world’s earliest chemical evidence of use of a medical numbing agent, according to a study published in Antiquity . “Six centuries ago, a Ming dynasty surgeon performed an operation with a pair of iron scissors and tweezers, and today we have read the traces of anesthetic medicine left on those instruments using a beam of laser light,” says study co-author Congcang Zhao , an archaeologist at China’s Northwest University, in a statement .…