“They tell us a kind of story about ourselves,” he said, one that is becoming ever more urgent.

Image Credit... Sonny Figueroa/The New York Times

When Mr. Young began the book, he imagined a “slim meditation on the idea of what a hoax is.” But history is rich and well larded with falsehoods, and Mr. Young, already a connoisseur of hoaxes — he described quizzing friends at dinner parties about their favorite hoax, and sharing some of his own (he’d been fascinated by the Spectra poetry hoax, a parody of Modernist poetry taken seriously, for one) — found plenty more that demanded attention. The book, both compendium and commentary, ballooned to nearly 500 pages.

“Bunk” traces a lineage of lies through time. It begins in the 18th century, with Shakespeare forgers and travel liars; makes its way through the 19th, with P. T. Barnum as a kind of ringmaster/hoaxmaster (among whose incredible acts was Joice Heth, a black woman whom he purported had been George Washington’s nursemaid — which would have made her, in Barnum’s time, 161 years old); and wends through the false memoirs and fake personae of the 20th and 21st. (In Mr. Young’s taxonomy the hoax, unlike a lie, a conspiracy theory or an urban legend, flirts with and delights in the possibility of discovery, at least in its early iterations.)

What the hoax returns to, both underpinning and undermining, Mr. Young found, is race. “I had a hunch that they would often deal with race,” Mr. Young said, but he was struck how often the hoaxes he found came back to the subject.” The hoax lays bare both prejudice (as did Barnum’s exhibiting of a black man as “What Is It?,” the missing link) and pilfering (as in the case of Rachel Dolezal, the former N.A.A.C.P. chapter president who had been living as a black woman until she was outed, in 2015, as white).

Mr. Young’s earlier book, “The Grey Album,” looked at the generative power of storytelling, but “Bunk” takes a bleaker view. The progression of the hoax, as Mr. Young describes it, is one from honor to horror. Early hoaxes validated: a young poet tracing a false genealogy between himself and the greats; Joice Heth providing a direct line between her 19th-century spectators and the father of the country. By the late 20th century, the hoax had turned grim: Mr. Young points to hoaxes like false Holocaust or Benghazi memoirs or even, in his view, Dylann Roof, the Charleston, S.C., shooter, whom Mr. Young sees as acting out in the service of a hoax — the hoax that is racism, in Mr. Young’s view — that perceives blackness, and black people, as a threat.

In its proximity to violence and its ever-more-accessible transmission via the internet, the hoax has metastasized, the stakes raised ever higher in what Mr. Young calls our “Age of Euphemism,” when “fake news” is a rallying cry for any unwelcome report. “In a way, the book is a prehistory to Trump,” said David Remnick, the editor of The New Yorker. “Donald Trump didn’t invent —” he used a word he acknowledged would be unpublishable in The Times — “but he has certainly upped the ante.”