1: the study of life forms generally malevolent to humans and not recognized by science as actual organisms, specifically those considered products of myth and folklore
2: the act of hunting such creatures
The Androphagi [Anthropophagi] have the most savage manners of all. They neither acknowledge any rule of right nor observe any customary law… [They] have a language all their own, and alone of all these nations they are man-eaters.
—Herodotus, The Histories of Herodotus (440 B.C.)
It is said that the Blemmyae have no heads and that their mouth and eyes are put in their chests. —Pliny the Elder, Naturalis Historiae (A.D. 75)
… another island, midway, live people of stature and ugly nature, which have no head and their eyes on the back and mouth, crooked as a horseshoe, in the midst of the breasts. On another island, there are many people without heads, and which has the eyes and head in the back.
—Wonders of the World (1356)
Gaora is a river, on the banks of which are a people whose head grow beneath their shoulders. Their eyes on in their shoulders, and their mouths in the middle of their breasts.
—Hakluyt's Voyages (1598)
To the west of Caroli are divers nations of Cannibals, and of those Ewaipanoma without heads. —Sir Walter Raleigh, The Discovery of Guiana (1595)
Wherein I spake of most disastrous chances,
Of moving accidents by flood and field,
Of hair-breadth scapes i' the imminent deadly breach…
And of the Cannibals that each other eat,
The Anthropophagi, and men whose heads
Do grow beneath their shoulders.
—Shakespeare, Othello (1603)
What's up with the epigraph?
The epigraph might just be the scariest part of the whole book. Why? Because it is a collection of different quotes in actual historical documents in which Anthropophagi are referenced. That's right, folks: Yancey did not make these creatures up. Well, okay—he kind of did.
All of these quotes actually come from legitimate documents in which various intellectuals set down accounts of their exotic travels. Herodotus, for example, is considered the father of Western history because of his nine-volume tome that describes the rise of the Persian Empire and the Greco-Persian Wars in the 5th century BC (source). Pliny the Elder was a famous Roman scholar whose Natural History was considered an authority on scientific matters up until the Middle Ages (source).
Richard Hakluyt was a prominent English geographer around the same time Shakespeare was writing his plays (you may have heard of him) (source), and Sir Walter Raleigh was one of the dudes who most famously explored the American colonies (source).
So if all of these really famous dead white dudes are all writing about Anthropophagi (or Blemmyae), why are they still considered mythical? Well, it has to do with some misconceptions about indigenous peoples populating the places these guys were exploring, some cultural insensitivity, as well as a case of one-of-these-things-is-not-like-the-other.
The word "Anthropophagus" is derived from Latin: anthro = man, phagus = eater, so it literally translates to "man-eater" (source). Another term for man-eaters is the more familiar "cannibal" (which is derived from terms coined by Columbus in his New World explorations). However, taking the word cannibal at face value—especially during this period of exploration in the late 1500s—is problematic:
Natives, when referenced, often fit the category of cannibal, a term that features prominently in Elizabethan imaginings of the wider world to the south, east, and west—although interestingly Raleigh and his companions are themselves mistaken for cannibals by one group of Arwacas. It was a relatively recent coinage, probably originating in Columbus's adaptation of New World terms such as 'carib' (Shakespeare's Caliban is a further derivation). But it also corresponds to the well-known classical figure of the Anthropophagus, the eater of human flesh described by Herodotus. While 'cannibal' was initially designated solely for those who were thought to eat their fellow humans, it quickly became a term used to signal any fearsome native or 'savage' (although it always retains associations with flesh-eating) and could be used to justify Christian European appropriation and colonisation. (The Elizabethan World, p. 669)
What this means, at least according to this source, is that in all likelihood the Anthropophagi that these guys were encountering were probably just the local natives, but their exotic "otherness" led the explorers to make some pretty drastic (and yeah, racist) assumptions.
So what's up with the whole headless-mouth-torso thing, then? Umm, well… we don't know. Maybe there really were creatures that looked like human-shark hybrids. Maybe these people held their bodies in a way that gave the impression of being headless. Maybe the explorers were taken in by elaborate costumes. Or maybe it's like the 16th century version of a rumor going viral.
This all may seem like a lengthy digression, but it's pretty important to the story. What Yancey has done is take something terrifying that has a mythological basis and made it real. If Sir Walter Raleigh and Pliny wrote about them, they must exist, right?