It all started in the 1970s (we think), when NBA Baltimore Bullets guard Fred Carter balled up his fist and bumped it against a teammate’s closed fist. Or maybe it was the Wonder Twins, who kissed fists and shouted “Wonder Twin powers, activate!” Soon, athletes and bros alike adopted the fist bump as the preferred greeting. In 2008, it received new prominence when Barack Obama and his wife fist-bumped as he accepted the Democratic presidential nomination. The Washington Post called it “the fist bump heard ’round the world.”

No matter the origin, fist bumps might actually be good for our health. A recent study finds that bumping fists rather than shaking hands in hospitals reduces the spread of bacteria.

Researchers, led by plastic surgeon Tom McClellan, asked people who had washed hands to either shake hands or bump fists. After the contact, the researchers took swabs of the subjects’ hands and cultured the samples to see how much bacteria were thriving on the hands. After 20 handshakes, people had more bacteria populating their hands than those who fist-bumped 20 times. A shake exposed three times as much skin as a bump and lasted 2.7 times longer.

“[Bumping] may lead to decreased transmission of bacteria and improved health and safety of patients and healthcare workers alike,” McClellan and his colleagues wrote in their paper in the Journal of Hospital Infection.

People spread germs via handshake because they fail to clean their hands properly. According to a study in The Journal of Environmental Health, only 5 percent of people wash their hands for 15 seconds or longer. But 15 seconds is not enough—the Centers for Disease Control and Prevention recommends that people wash their hands for 20 seconds to reduce the spread of illness. This improper handwashing means that 80 percent of people carry germs on their hands. When one improperly cleaned hand grasps another in a welcoming handshake, the two swap germs that can cause everything from a cold to MRSA to pneumonia to E. coli. While McClellan’s study focused solely on bacteria, he plans on investigating how fist bumps can impact the spread of viruses.

If you’re doing it like this, you’re doing it wrong! stop!

Mental Floss