Gulliver's Travels
by Jonathan Swift

Their Heads and Breasts were covered with a thick Hair, some frizzled and others lank; they had Beards like Goats, and a long ridge of Hair down their Backs and the fore-parts of their Legs and Feet, but the rest of their Bodies were bare, so that I might see their Skins, which were of a brown buff Colour. They had no Tails, nor any Hair at all on their Buttocks, except about the Anus; which, I presume, Nature had placed there to defend them as they sate on the Ground; for this Posture they used, as well as lying down, and often stood on their hind Feet. They climbed high Trees, as nimbly as a Squirrel, for they had strong extended Claws before and behind, terminating in sharp points, and hooked. They would often spring, and bound, and leap with prodigious Agility. The Females were not so large as the Males, they had long lank Hair on their Heads, but none on their Faces, nor any thing more than a sort of Down on the rest of their Bodies, except about the Anus, and Pudenda. Their Dugs hung between their Fore-feet, and often reached almost to the Ground as they walked. The Hair of both Sexes was of several Colours, brown, red, black and yellow. (IV:1;4)

Swift invented the word "Yahoo" for the Travels. He and his friends used the word in their correspondence as an inside joke while Swift was writing the book. Researchers have identified a number of possible sources for the word. Clark, in his extended analysis of Swift's "little language" has rendered it as a derivation of the sound whinny which is also the root for houyhnhnm.

Equally, a number of sources have been suggested for the Yahoos themselves, including some native peoples and certain other primates recently encountered and described by European travellers. This device allows Swift to criticize human nature indirectly, similar to the way he managed to criticize English goverment by rendering it tiny in Part I. The technical term for this technique, used extensively in science fiction, is "cognitive estrangement."

For additional sources for Part IV and the Yahoos, see Sources: Literary Criticism & Interpretation: HouyhnhnmLand

... the Houyhnhnms have no Word in their Language to express any thing that is Evil, except what they borrow from the Deformities or ill Qualities of the Yahoos. Thus they denote the Folly of a Servant, an Omission of a Child, a Stone that cut their Feet, a continuance of foul or unseasonable Weather, and the like, by adding to each the Epithet of Yahoo. For Instance, Hhnm Yahoo, Whnaholm Yahoo, Ynlhmndwihlma Yahoo, and an ill-contrived House, Ynholmhnmrohlnw Yahoo. (IV:9;11)