German physician Robert Koch, noting fellow German Ferdinand Cohn's report of a spore stage of a certain bacterial species, traced the life cycle of Davaine's bacteridia, identified spores, inoculated laboratory animals with them, and reproduced anthrax—a breakthrough for experimental pathology and germ theory of disease. Pasteur's group added ecological investigations confirming spores' role in the natural setting, while Koch published a landmark treatise in 1878 on the bacterial pathology of wounds. In 1881, Koch reported discovery of the "tubercle bacillus", cementing germ theory and Koch's acclaim.

Japanese physicians immediately recognized the values of X-Rays. They were able to purchase the equipment locally from the Shimadzu Company, which developed, manufactured, marketed, and distributed X-Ray machines after 1900.[149] Japan not only adopted German methods of public health in the home islands, but implemented them in its colonies, especially Korea and Taiwan, and after 1931 in Manchuria.[150] A heavy investment in sanitation resulted in a dramatic increase of life expectancy.[151]

In East Semitic cultures, the main medicinal authority was a kind of exorcist-healer known as an āšipu.[8][9][10] The profession was generally passed down from father to son[8] and was held in extremely high regard.[8] Of less frequent recourse was another kind of healer known as an asu, who corresponds more closely to a modern physician[7] and treated physical symptoms using primarily folk remedies composed of various herbs, animal products, and minerals, as well as potions, enemas, and ointments or poultices.[7] These physicians, who could be either male or female, also dressed wounds, set limbs, and performed simple surgeries.[7] The ancient Mesopotamians also practiced prophylaxis[7] and took measures to prevent the spread of disease.[7]

As infectious diseases have become less lethal, and the most common causes of death in developed countries are now tumors and cardiovascular diseases, these conditions have received increased attention in medical research. Tobacco smoking as a cause of lung cancer was first researched in the 1920s, but was not widely supported by publications until the 1950s. Cancer treatment has been developed with radiotherapy, chemotherapy and surgical oncology.
The sexual revolution included taboo-breaking research in human sexuality such as the 1948 and 1953 Kinsey reports, invention of hormonal contraception, and the normalization of abortion and homosexuality in many countries. Family planning has promoted a demographic transition in most of the world. With threatening sexually transmitted infections, not least HIV, use of barrier contraception has become imperative. The struggle against HIV has improved antiretroviral treatments.

The medicinal leech has been in use for thousands of years, and is even today considered to be a way of restoring venous circulation after reconstructive surgery. But it was in the early 19th century that the leech really soared in popularity. Led by French physician François-Joseph-Victor Broussais (1772–1838), who postulated that all disease stemmed from local inflammation treatable by bloodletting, the ‘leech craze’ saw barrels of the creatures shipped across the globe, wild leech populations decimated almost to extinction, and the establishment of prosperous leech farms.
1950s: A series of successful anti-psychotic drugs are introduced that do not cure psychosis but control its symptoms. The first of the anti-psychotics, the major class of drug used to treat psychosis, is discovered in France in 1952 and is named chlorpromazine (Thorazine). Studies show that 70 percent of patients with schizophrenia clearly improve on anti-psychotic drugs.

The authors also provide examples of how evolutionary principles can direct future research. They reference new research looking into the role of intestinal parasites and autoimmune diseases. The research is based upon the premise that humans co-evolved not only with our intestinal flora, but with certain parasites, such as intestinal worms. Now we live in a largely hygienic environment, and have even taken steps to eliminate parasites. This may have unintentionally deprived our immune systems of needed stimulation, resulting in poor immune regulation, and subsequent increase in auto-immune diseases like asthma and multiple sclerosis.
^ Hayward, Rhodri (2011). "Medicine and the Mind". In Jackson, Mark. The Oxford Handbook of the History of Medicine. Oxford University Press. pp. 524–42. ISBN 978-0199546497.; Scull, Andrew (2005). Most Solitary of Afflictions: Madness And Society in Britain, 1700–1900. Yale University Press. pp. 324–28. ISBN 978-0300107548.; Dowbiggin, I. (1992). ""An exodus of enthusiasm": G. Alder Blumer, eugenics, and US psychiatry, 1890–1920". Medical History. 36 (4): 379–402. doi:10.1017/S002572730005568X. PMC 1036631. PMID 1435019.; Snelders, S.; Meijman, F.J.; Pieters, T. (2007). "Heredity and alcoholism in the medical sphere: The Netherlands, 1850–1900". Medical History. 51 (2): 219–36. doi:10.1017/S0025727300001204. PMC 1871693. PMID 17538696.; Turda, M. (2009). ""To end the degeneration of a nation": Debates on eugenic sterilization in inter-war Romania". Medical History. 53 (1): 77–104. doi:10.1017/S002572730000332X. PMC 2629178. PMID 19190750.
Retinal neurons and their axon output have evolved to be inside the layer of retinal pigment cells. This creates a constraint on the evolution of the visual system such that the optic nerve is forced to exit the retina through a point called the optic disc. This, in turn, creates a blind spot. More importantly, it makes vision vulnerable to increased pressure within the eye (glaucoma) since this cups and damages the optic nerve at this point, resulting in impaired vision.
In 1953 Jonas Salk announced he had a vaccine for poliomyelitis. A vaccine for measles was discovered in 1963. Meanwhile surgery made great advances. The most difficult surgery was on the brain and the heart. Both of these developed rapidly in the 20th century. A Swede named Rune Elmqvist invented the first implantable pacemaker in 1958. The first heart transplant was performed in 1967 by Christiaan Barnard. The first artificial heart was installed in 1982. The first heart and lung transplant was performed in 1987.
Cardiology used to be the study of the heart - but in the last couple decade it's been more about the study of cardiac procedures. Not all of these procedures have long term benefits and most just treat the symptoms and do not prevent future events. Dr. Masley looks at this from a preventative and lifestyle medicine perspective and works to educate both patients and practitioners on what they can do to avoid seeing a cardiologist altogether. 
As you pointed out, 80% just want a prescription and are not willing to find the causes of their illness, I have chosen to focus on the 20% who are willing to discover the causes and make lifestyle changes. Patient satisfaction is up, and I am getting control back of my practice. I believe this the medicine of the future, that will appeal to my grandchildren.