The bubonic plague killed one third of Europe's population between 1348 and1350, making it the most deadly epidemic since the sixth century. With no cure available, and no clue as to what caused the disease, many believed it was God's punishment for sinful behavior. The plague had a massive effect on every aspect of society: serfs were freed, the labor force was decimated, and cultivation of food ceased. Doctors were forced to think of medicine in a new way, leading to the rise of the scientific theory.
1628: Harvey discovers circulatory system
Dr. William Harvey, an English physician, made medical history when he published his discovery that blood, driven by the pumping of the heart, is constantly on the move throughout the human body. This disproved the previous medical wisdom that the heart's main purpose was to keep blood warm.
1882:Germs proven to cause disease
In 1864, Louis Pasteur amazed the scientific community by proving that microorganisms live in the air. Years later, German scientist Robert Koch announced his findings that specific microorganisms can be linked to specific diseases in what is now known as the "germ theory of disease." His discovery instantly improved physicians' ability to diagnose and treat patients, as well as expanding human understanding of cleanliness as a means to prevent disease.
1928:Fleming discovers penicillin
Scottish physician Alexander Fleming accidentally discovered the ability of molds to destroy sickness–causing bacteria, when he noticed that mold growing on a staphylococcus culture had killed parts of the culture. Penicillin, the antibiotic derived from mold, allows doctors to easily treat patients for a variety of ailments previously considered incurable, including pneumonia, tetanus, gangrene, and scarlet fever as well as more mundane illnesses like respiratory and ear infections.
Andreas Vesalius took the medical community by storm by revealing the true skeletal and muscular structure of humans for the first time and correcting more than 200 errors in the common thinking among doctors of the day. Unfortunately, his contribution was tarnished in his own time by the legal and moral taboo against the dissection of human bodies—Vesalius's main source of research.
English doctor Edward Jenner stumbled upon a way to prevent smallpox when he noticed that milkmaids who had developed cowpox didn't get the dreaded disease. His resulting vaccine, made from the cowpox virus, virtually wiped out smallpox, which had killed more than sixty million Europeans in the eighteenth century. His vaccine also gave credence to the science of immunology, leading to the development of vaccines for other deadly diseases, including diphtheria, polio, and measles.
1866:Mendel's Law of Heredity
Through his work crossbreeding different varieties of the garden pea, Austrian monk Gregor Mendel advanced the idea that traits are transferred from parents to progeny by way of distinct units and formulated mathematical laws governing the inheritance of these traits. Mendel's "law" was eventually proven true for both plants and animals. His findings were rediscovered in the early twentieth century, allowing farmers to reproduce positive traits in plants and create healthier, stronger crops of food.
Margaret Sanger sparked the birth control movement with the publication of The Woman Rebel, in which she encourages women to view conception as a choice rather than an obligation. In 1923, her tireless efforts resulted in the establishment of America's first legal birth control clinic, which served as a contraceptive dispensary and research facility under the auspices of the American Birth Control League (one of the groups that eventually morphed into Planned Parenthood). The birth control movement has had far-reaching, worldwide implications, from women's rights to population control to the sexual revolution.