From Anatomy to Antibiotics: Eight Scientists Who Changed How Medicine Knows Disease

Vesalius published De Humani Corporis Fabrica in 1543 after dissecting human cadavers himself, and the book corrected hundreds of errors in the Galenic anatomy that had stood for over a thousand years. He also taught by cutting in front of his students, which made direct observation the basis of anatomy.

Harvey published De Motu Cordis in 1628 and argued from quantity: the heart pumps far more blood in an hour than the body could manufacture, so the same blood must circulate. He backed the argument with experiments tying off vessels in living animals; the capillaries that complete the circuit were not seen until microscopes improved, decades after his death.

On 14 May 1796 Jenner inoculated eight-year-old James Phipps with cowpox matter and later exposed him to smallpox, and the boy did not fall ill. He published in 1798 and named the method vaccination, and it spread widely long before anyone could explain why it worked.

In 1847 at Vienna General Hospital, Semmelweis compared a doctors' maternity ward with a midwives' ward and found childbed fever deaths several times higher in the first. When he required handwashing in chlorinated lime solution, deaths fell sharply, though most of his peers rejected his explanation because no germ theory existed yet.

In 1854 Snow plotted cholera cases in Soho and traced the cluster to a single Broad Street pump, noting that a nearby workhouse and brewery with their own water supply were spared. His reasoning was inference from pattern rather than proof of a germ, and it challenged the prevailing belief that bad air caused disease.

Pasteur established that microorganisms cause fermentation and disease, the work that founded modern germ theory, and went on to develop pasteurization and vaccines against anthrax and rabies. This stop supplies the explanation that the earlier stops on infection and contagion had been missing.

Lister learned of Pasteur's germ theory in 1865 and began using carbolic acid on instruments, wounds and the operating air. At Glasgow Royal Infirmary, where about 45 to 50 percent of amputation patients had died of sepsis, his ward's mortality fell from around 45 percent to about 15 percent within four years.

In September 1928 Fleming noticed that a mould, later identified as Penicillium notatum, had killed Staphylococcus bacteria on a contaminated plate at St Mary's Hospital. He published in 1929 but could not purify the penicillin himself; Howard Florey and Ernst Chain did that, and the three shared the 1945 Nobel Prize in Physiology or Medicine.