Smoking gives you lung cancerPascal le Segretain/Getty Images
The first studies connecting smoking to lung cancer came out as early as 1939, but many doctors contended that cancer was largely due to other factors such as air pollution until the early 1960s.
Bacteria produce ulcersChina Photos/Getty Images
Australian physicians Robin Warren and Barry Marshall identified the link between Helicobacter pylori and ulcers in 1982, but the medical community maintained that the causes were stress and/or diet until the mid-1990s when the NIH acknowledged the connection.
Aspirin lowers heart attack riskTim Boyle/Getty Images
A California physician named Lawrence Craven first published research showing aspirin’s anti-clogging effect back in 1950, but his practice of prescribing an aspirin a day to keep heart disease away wasn’t widely adopted until about 40 years later.
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Radiation can be harmfulJustin Sullivan/Getty Images
Research linking X-rays to leukemia and other cancers was published in 1911, but X-rays, used everywhere from doctors’ offices to shoe stores (yes, really!) were generally considered safe until the National Academy of Sciences issued a report condemning these practices (including use in pregnant women) in 1956.
A virus causes cervical cancerJoe Raedle/Getty Images
In the late 1970s, German virologist Harald zur Hausen published research suggesting that the human papillomavirus causes cervical cancer. Many scientists mocked his claim, but in 2008 he won the Nobel Prize for his research—and children today are routinely vaccinated against HPV.
Watch The Doctors daily for more fascinating facts and feel-great tips (check local listings).