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.

“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.”

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.”

“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.”