Medusa's Gaze and Vampire's Bite: The Science of Monsters by Matt Kaplan

faint at the sight of blood or upon seeing other psychologically distressing things.
    Although the causes of these various forms of shock are different, they all result in the brain being denied the oxygen and glucose it needs to survive. When this happens, the brain starts having troublefunctioning. The symptoms are often the same: Patients become disoriented, nauseated, and dizzy while their limbs become cold, tingly, and stiff as a result of reduced blood circulation. In a sense, the tingly paralysis that people often feel in their legs after sitting for too long is kind of like a localized, nonlethal taste of what shock patients feel in all their limbs. Moreover, a lack of blood flow to the brain can trigger seizures that sometimes lead to a state of boardlike stiffness in the body.
    Human bodies worked the same way thousands of years ago and the ancient Greeks would have experienced the identical symptoms of psychogenic shock. With this in mind, it is tantalizing to consider the possibility that the concept of Medusa’s petrifying gaze stems from someone who felt the icy grip of this shock upon seeing something frightening or worse, had a seizure from the experience, and entered a state of severe rigidity. But what of the strange notion that her hair was made of snakes? How did such a trait find its way into the myth of the monster, and what fears was this feature representing?
Sensible serpents
    There are no living organisms that have heads covered in writhing snakes and, to date, there are no fossils indicating that such organisms ever existed. Why select snakes? Medusa could have had a head covered in tendrils like those on jellyfish or even tentacles like the limbs of a squid or an octopus. Yet the myths about her are consistent and specific: She always has hair of writhing snakes. This is not an accident.
    Snakes kill people. Whether they are anacondas that squeeze the life out of humans stupid enough to swim in their jungle waters or cobras that inject venom with their fangs, snakes are a major threat to human life in many parts of the world today and there is evidence that this has always been the case. A 1978 study led by James Larrick at Duke University analyzed interactions between venomous snakesand the Waorani of Ecuador’s Amazon rain forest. He found that 45 percent of the nearly six hundred individuals in the native population had experienced at least one snakebite and that about half of the people had been bitten more than once. As for the snakebite mortality rate, data collected on deaths over six generations indicated it had long hovered around 4 percent, roughly twice the 2.1 percent mortality rate that traffic accidents inflict on the developed world. True, with the invention of antivenins and emergency rooms, snakebites are now becoming less of a threat than they once were, but they were a terrible danger until very recently.
    It is difficult to determine when highly venomous snakes and our primate ancestors first started mingling, since venom does not fossilize as bone does. However, venom injection mechanisms, like the hollow hypodermic needle teeth in venomous snake skulls, do sometimes get preserved and can hint at venom having once been present. Some fossil reptiles with hollow fangs have been dug up in Triassic sediments dating back to around two hundred million years ago, long before primates evolved. What these hollow fangs were used for cannot be determined for certain, but the paleontology team that made the find, led by Jonathan Mitchell at the University of Chicago, theorized in 2010 in the journal Naturwissenschaften that these ancient fangs were probably used for injecting venom. This suggests that venomous reptiles have been around since the days when mammals were only just beginning to evolve. Yet Mitchell’s toothy find, named Uatchitodon, is more similar to a lizard than to a snake and is unlikely to have been on the same evolutionary path as modern snakes.
    Other work, led by