To be a guinea pig

Origin

Guinea pigs, small rodents originating from the Andes, were first brought to Europe in the 16th century, valued initially as exotic pets. However, it was their compliant nature and physiological similarities to humans that soon made them indispensable to the burgeoning world of scientific research. By the 19th century, laboratories across the continent were routinely using these creatures for medical experiments, drug trials, and disease studies. Their role as the primary, often unwilling, subjects of testing became so ubiquitous that their very name became shorthand for anyone—animal or human—who is subjected to an experimental or trial process, cementing the image of the "guinea pig" as the first one to face the unknown.