Editor's Note: This story was originally published in the May 2003 issue of Scientific American.

The world lost the creators of two of its most celebrated biohoaxes recently: Douglas Herrick, father of the risibly ridiculous jackalope (half jackrabbit, half antelope), and Ray L. Wallace, paternal guardian of the less absurd Bigfoot. The jackalope enjoins laughter in response to such peripheral hokum as hunting licenses sold only to those whose IQs range between 50 and 72, bottles of the rare but rich jackalope milk, and additional evolutionary hybrids such as the jackapanda. Bigfoot, on the other hand, while occasionally eliciting an acerbic snicker, enjoys greater plausibility for a simple evolutionary reason: large hirsute apes currently roam the forests of Africa, and at least one species of a giant ape—Gigantopithecus— flourished some hundreds of thousands of years ago alongside our ancestors.

Is it possible that a real Bigfoot lives despite the posthumous confession by the Wallace family that it was just a practical joke? Certainly. After all, although Bigfoot proponents do not dispute the Wallace hoax, they correctly note that tales of the giant Yeti living in the Himalayas and Native American lore about Sasquatch wandering around the Pacific Northwest emerged long before Wallace pulled his prank in 1958.

In point of fact, throughout much of the 20th century it was entirely reasonable to speculate about and search for Bigfoot, as it was for the creatures of Loch Ness, Lake Champlain and Lake Okanagan (Scotland’s Nessie, the northeastern U.S.’s Champ and British Columbia’s Ogopogo, respectively). Science traffics in the soluble, so for a time these other chimeras warranted our limited exploratory resources. Why don’t they now? The study of animals whose existence has yet to be proved is known as cryptozoology, a term coined in the late 1950s by Belgian zoologist Bernard Heuvelmans. Cryptids, or “hidden animals,” begin life as blurry photographs, grainy videos and countless stories about strange things that go bump in the night. Cryptids come in many forms, including the aforementioned giant pongid and lake monsters, as well as sea serpents, giant octopuses, snakes, birds and even living dinosaurs.

The reason cryptids merit our attention is that enough successful discoveries have been made by scientists based on local anecdotes and folklore that we cannot dismiss all claims a priori. The most famous examples include the gorilla in 1847 (and the mountain gorilla in 1902), the giant panda in 1869, the okapi (a short-necked relative of the giraffe) in 1901, the Komodo dragon in 1912, the bonobo (or pygmy chimpanzee) in 1929, the megamouth shark in 1976 and the giant gecko in 1984. Cryptozoologists are especially proud of the catch in 1938 of a coelacanth, an archaic-looking species of fish that had been thought to have gone extinct in the Cretaceous.

Although discoveries of previously unrecorded species of bugs and bacteria are routinely published in the annals of biology, these instances are startling because of their recency, size, and similarity to cryptid cousins Bigfoot, Nessie, et al. They also have in common—a body! In order to name a new species, one must have a type specimen—a holotype—from which a detailed description can be made, photographs taken, models cast and a professional scientific analysis prepared.

If such cryptids still survived in the hinterlands of North America and Asia, surely by now one would have turned up. So far all we have are the accounts. Anecdotes are a good place to begin an investigation—which by themselves cannot verify a new species. In fact, in the words of social scientist Frank J. Sulloway of the University of California at Berkeley—words that should be elevated to a maxim: “Anecdotes do not make a science. Ten anecdotes are no better than one, and a hundred anecdotes are no better than ten.”

I employ Sulloway’s maxim every time I encounter Bigfoot hunters and Nessie seekers. Their tales make for gripping narratives, but they do not make sound science. A century has been spent searching for these chimerical creatures. Until a body is produced, skepticism is the appropriate response.