Who was the first person to use animal testing?

The origins of animal testing can be traced back to ancient civilizations, but the first documented use is often attributed to Greek physician Hippocrates around 400 BCE, who conducted experiments on animals to understand anatomy and disease. However, it was not until the 19th century that systematic animal experimentation began to take shape, particularly with the work of scientists like Louis Pasteur and Robert Koch, who used animals to study infections and vaccines.