Modern audiences do not find dragons frightening. Fascinating as mythical creatures, yes, but terrifying, no. Yet, present them with a story about a virus that can kill a healthy adult in hours and they will have nightmares for weeks. The difference between the two is believability. Monsters are at their most frightening when they carry characteristics that tie them to the real world in some way. Preposterous as they might seem today, dragons were no different in ancient times. Humans long ago stumbled upon skeletons that had sharp teeth and talon-like claws. These fossils were real and some were frighteningly large. Those who looked at them could only guess at how dangerous the animals that they belonged to must have been. From such interactions, dragons were born. Yet, in spite of ample physical evidence that dragons existed, none were ever seen in the flesh. Dragon bones were ultimately proven to be the bones of huge predatory dinosaurs like Tyrannosaurus Rex, but before the mystery was solved, they were the makings of frightening beasts that managed to evade human sight by lurking deep within the shadows of the wild. The Science of Monsters will explore monsters that have haunted humanity throughout the ages, from Medusa to sea serpents, giants, and vampires. In each chapter Kaplan uses scientific principles, current research, and his thorough knowledge of the natural world to explain why specific monsters came to be and what it was about them that was so terrifying to the people who brought them to life.

With the explosion of knowledge taking place in recent decades, scientists are constantly discovering that things they have been certain about are wrong: the continents they thought had been in place forever actually drift around; the cells we are made of are not simple but infinitely complex; our genus has been on Earth many times longer than they thought. And increasingly, there is compelling evidence that scientists are wrong about our living relatives. One thing considered certain was that the giants and wild men in stories from all over the world are entirely imaginary. Now that belief is under serious challenge. Forty-five years ago, giant footprints found in northern California brought Bigfoot to the attention of many revived interest in Canada's Sasquatch. Every year since then additional evidence has accumulated, and now that witnesses can submit information via the internet, the trickle of reports has become a flood. John Green has been in the thick of things from the beginning. In "Sasquatch, The Apes Among Us", first published in 1978, he sampled the evidence from the earliest records up the late 1970s and from all around the world, then concentrated on two aspects of the subject: the nature of the animal described and the wealth of reports from parts of North America outside the Pacific Northwest. When it came out, "The Apes Among Us" was acclaimed as the definitive work on the fascinating subject of whether humans share North America with a giant bipedal primate that is unknown to science. Since then, evidence for the existence of that unknown primate has grown exponentially, and individual scientists have written books about aspects of it. Remarkably, however, to most of the scientific world, the evidence remains unknown and unexplored, and for those who do follow the subject this is still the definitive book.