Ancient Healers: How People First Mapped the Human Body

More than 2,300 years ago, in the Egyptian city of Alexandria, a doctor named Herophilus did something almost no one had done before: he cut open human bodies to see exactly what was inside. He counted the parts of the eye, traced nerves down the spine, and figured out that the brain -- not the heart -- controls thought. His notebooks are lost today, but later writers copied his findings, and historians still call him the "Father of Anatomy."

- How ancient Egyptians learned about organs through mummification - Why Greek doctors like Hippocrates and Herophilus changed medicine forever - How Andreas Vesalius corrected 1,300 years of mistakes in 1543 - How X-rays and MRI let doctors see inside living bodies without cutting

Around 2600 BCE, Egyptian embalmers removed the liver, lungs, stomach, and intestines from a body before wrapping it as a mummy, storing each organ in its own canopic jar. They left the heart in place because they believed it held a person's memory and personality. Embalmers weren't scientists -- they were preparing people for the afterlife -- but the process gave them more hands-on knowledge of human organs than almost anyone else in the ancient world.

Around 400 BCE, the Greek physician Hippocrates argued that illness came from natural causes in the body, not from angry gods -- a huge shift in thinking. About a century later, Herophilus went further by dissecting human bodies in Alexandria, Egypt, one of the few places in the ancient world where this was legally allowed. He described the retina of the eye, distinguished arteries from veins, and named the duodenum, a part of the small intestine we still call by that name today.

In 1543, a 28-year-old professor named Andreas Vesalius published De Humani Corporis Fabrica ("On the Fabric of the Human Body"), based on dissections he performed himself in Padua, Italy. His detailed drawings proved that Galen had made real mistakes -- for example, the human jawbone is one bone, not two, as Galen had claimed from studying animals. Vesalius's book is considered the start of modern anatomy because it was based on direct observation instead of old assumptions.

In 1895, German physicist Wilhelm Roentgen discovered X-rays and used them to photograph the bones inside his wife's hand -- the first medical image ever made without surgery. Nearly 80 years later, in the 1970s, MRI (magnetic resonance imaging) let doctors see soft tissue like muscles and organs in detail. Today, a surgeon can study a 3D scan of a patient's exact anatomy before ever making a cut.