As knowledge about the actual biological workings of the human body developed, so too did better and more effective medical treatments. Although vaccines became more effective and more numerous in the 19th and 20th centuries, the first vaccine was developed in 1796, and so is outside of the 125 year range. Perhaps the most important medical breakthrough in that range was the development of antibiotics. While the concept of antibiotics was theorized and put to experiments as early as the 1870s, the first really effective antibiotic was Arsphenamine, or Salvarsan, discovered in 1910 by Sahachiro Hata. This antimicrobial agent was useful in battling syphilis, which was common at the time. Later, Vincenzo Tiberio discovered Penicillium mold to be antibiotic, and its efficacy against harmful bacteria was proved by Alexander Fleming in 1928. Penicillin became the first mass-produced antibiotic to be truly effective against many harmful bacteria, and is responsible for saving millions of lives throughout the years.

The breakthrough in antibiotics meant that many diseases caused by bacteria were now treatable, extending the overall lifespan and preventing epidemics of untreated disease. Although certain bacteria are becoming resistant to antibiotics because of increased population growth and overuse, antibiotics are still a powerful tool in medicine and health care.