The effects of evolution are sometimes difficult to perceive in daily life, making public skepticism of the existence of evolution all the more challenging to address. Perhaps the foremost example used to counter these notions is the widespread problem of resurgent diseases that had been previously treated through antibiotics, especially evolved resistance in bacterial pathogens. Although naturally produced antibiotics evolved in microbial communities long before humans appeared as a species, the medical realm began earnestly administering antibiotic drugs only since their discovery in the 1950s. Widespread production and utilization of antibiotics in medicine and agriculture, however, has created a massive uncontrolled experiment in which bacteria have been selected to harbor antibiotic resistance genes, making existing therapies largely ineffective in many clinical circumstances.