After Helen Gahagan Douglas was elected as a Democratic representative in 1944, news outlets spread rumors of a vicious rivalry between her and Republican congresswoman Clare Boothe Luce; one headline read helen vs. clare: torch vs. icicle. “For reporters short of real news,” Douglas complained, “it was a simple day’s work to speculate that we would claw at one another.” The women resolved to avoid giving fodder to such baseless stories by never discussing the same subject on the same day.

“His method was inefficient in the extreme,” scoffed Nikola Tesla in 1931 in a New York Times obituary for his former employer and longtime scientific competitor, Thomas Edison. “In view of this, the truly prodigious amount of his actual accomplishments is little short of miracle.”

British historian Orlando Figes admitted in 2010 to posting scathing reviews on Amazon for books by other Russian-history specialists. Using the name Historian, he called one work “dense and pretentious” and complained another was not “worth the bother of ploughing through its dreadful prose.” Of Figes’ own The Whisperers, Historian posted that it “leaves the reader awed, humbled, yet uplifted” and wrote of its author, “I hope he writes forever.”

“Those on the right and those on the left you have placed in your lap,” proclaimed an Assyrian prophetess in 680 bc in support of King Esarhaddon, who had defeated his brothers in civil war. Another prophetess promised to “tear apart” those “conniving polecats and rats.”

“I have personally watched and studied a jealous baby,” Saint Augustine reports in his Confessions. “He could not speak and, pale with jealousy and bitterness, glared at his brother sharing his mother’s milk.” Regarding the baby’s sinister intent, Augustine contends that “it can hardly be innocence,” when the milk “is flowing richly and abundantly, not to endure a share going to one’s blood brother, who is in profound need.”

Afridi tribesmen agreed not to engage in traditional blood feuds on a road through the Khyber Pass after it was seized by the British Raj in 1879. One result, the writer E.F. Benson later reported, was that Afridis would travel through clandestine tunnels to the road to “smile at each other.” Then, “having taken the air,” he wrote, “they rabbit it into their fortresses again.”

In love with the same slave girl, Iris, two men in first-century Pompeii fought via graffiti. Severus tagged the wall first, writing that Iris did not love Successus, adding, “His rival wrote this.” Successus responded, “Don’t even think to speak badly of a man more handsome than you, especially one who is both most vicious when crossed and yet also good.” “I have written all there is to say,” Severus retorted. “You love Iris, but she does not love you.”

Carl Jung attributed his split with his mentor Sigmund Freud around 1910 in part to a generational divide. “Our descendants are our most dangerous enemies,” Jung argued, “for they will outlive us, and, therefore, without fail, will take the power from our enfeebled hands.”

“Against the fashionable (and idiotic) claim that revenge is just hardwired and an instinctual response programmed into our genes and neuro-structures,” argues law professor William Ian Miller in an analysis of Njál’s Saga, “actual Icelandic feuding” rather “made it preferable for revenge to be served up cold; take your time and think. Only the stupid hit back right away.”

In the Texas border town of Lajitas, generations of goats named Clay Henry have since 1986 served as mayor from a pen outside the general store, where passersby often stop to give them beer. In 2001 a local man became envious that Clay Henry III was allowed to drink alcohol on Sunday in the blue law–abiding county. “The next morning,” the local sheriff reported, “the goat was found lying with its testicles cut off.”

Russian legend holds that the first dog was created without fur. He soon lost patience waiting for it and so ran after a passing stranger, who turned out to be the devil. Owing to this evil allegiance, the fur originally intended for him went instead to the first cat, from which derives the antipathy between their descendants: dogs believe cats have stolen their property.

Dynamite magnate Alfred Nobel omitted mathematics from the final list of categories his prizes would specifically recognize, claiming the prize for physics would cover it. Rumors circulated—likely helped along by the miffed Gösta Mittag-Leffler, Sweden’s leading mathematician—that this was due to a romantic rivalry between Nobel and Mittag-Leffler; the woman had chosen the mathematician, and punishing the whole field was Nobel’s revenge.

In 1873, as part of the Bone Wars, paleontologist Othniel Charles Marsh complained in The American Naturalist that his rival, Edward Drinker Cope, was dentally inept; he “mistook canines for incisors, nasals for frontals, maxillaries for premaxillaries, maxillaries for nasals, and maxillaries for frontals!” Cope claimed he was “too fully occupied on more important subjects.”

Ornithologists have found that hormones strongly determine aggression between sibling seabirds. Blue-footed boobies rarely attack a nest mate, while among Nazca boobies—born with androgen levels three times higher—the elder of two hatchlings unconditionally attacks and kills the younger one shortly after birth.

While uniting rival clans into a nation in the third millennium bc, China’s Yellow Emperor is said to have established prohibitions against feuding by making a gruesome example of one rebellious leader—peeling the man’s skin off to use for target practice, stuffing his stomach to make a ball to kick around, and fermenting his flesh and bones into a bitter broth to drink.