helped her resist the urge to breathe for far longer than most people. Some have suggested that the ability to voluntarily hold your breath is evidence of a watery episode in human evolution. It’s even been said that humans have an ability to lower heart rate and metabolic rate in order to breath-hold for even longer. Other anatomical and physiological bits and bobs – our hairlessness, the distribution of our subcutaneous fat and even our tendency to walk on two legs – have been linked to an aquatic phase of evolutionary development. Unfortunately, the cobbled-together “aquatic ape hypothesis” fails to hold water. It’s a romantic notion that may appeal to us but, with the cold light of day falling on the scientific evidence, it’s revealed to be nothing more than a fiction. Looking at voluntary breath-holding, it turns out that we’re certainly not unique among non-aquatic mammals in being able to hold our breath. (Having said that, it’s a difficult thing to investigate in other mammals as, unlike humans, they tend not to comply when you ask them to breath-hold.) And experimental evidence shows that heart rate doesn’t drop during breath-holding. At least, it doesn’t if you’re breath-holding on land. When you’re submerged in cold water it’s a different story: cooling the face does lead to a slower heart rate in most people. But, once again, this