Why do Olympic winners bite their medals?

So why are they doing it?

Although first-place Olympic medals haven't been made of real gold since 1912, an easy way that athletes would test them to be sure they were the real thing was to sink their teeth into the material.

Gold is a malleable metal, and biting into gold would leave an indentation; athletes' teeth would leave a mark.

But these days, Olympic gold medals are only 1.34 percent gold, The Washington Post reported. Most of the medals are made from mostly sterling silver and recycled silver.

>> Here's what the 2016 Rio Olympic medals look like

Olympic winners bite their medals as symbolism and to give photographers a pose to capture besides just smiles.

"It's become an obsession with the photographers," David Wallechinsky, president of the International Society of Olympic Historians, told CNN in 2012. "I think they look at it as an iconic shot, as something that you can probably sell. I don't think it's something the athletes would probably do on their own." 

According to Rio 2016, the gold medals are free of mercury and "have been made with sustainability at their heart."

In addition to the gold medals, American Olympic winners get $25,000 prizes.