Not everyone has it, but for those who do, it could be a life-saver one day.

It's called the "mammalian diving reflex" and it's the reason why victims of icy plunges into chilly water can survive the effects of hypothermia.According to Discover magazine, the diving reflex occurs in aquatic mammals, such as seals or beavers and humans. When submerged, the mammal automatically stops breathing and its heart rate decreases. In addition, the body channels blood mainly to the heart and brain. These defensive reactions allow the victim to stay submerged for long periods with no ill effects.