Oliver Plunkett, Archbishop of Armagh, was the last Catholic martyr to die at Tyburn, in 1681. He was hanged, drawn and quartered, and stray bits of his corpse were distributed among waiting friends. Three centuries later a scrap of linen that had touched part of his body was said to have cured an elderly Italian of her deadly disease, so Plunkett was canonised in 1975. As a child in Ireland in that decade, I knew all about Plunkett and his obscene end: my mother had hung a portrait of him in my bedroom, and I’d torment myself by turning it over to read an account of the execution – ‘his bowels taken out and burned before his eyes’. Consequent nightmares were all the more lurid because at St Peter’s Church in Drogheda – on a primary-school excursion, no less – I had looked in those very eyes, or at least their sockets, and imagined a July morning in London when the saint’s guts lay on the ground.

The shrivelled brown head of Plunkett, immured in its elaborate vitrine, is one of many instructive relics or trophies in Severed, Frances Larson’s fascinating book. Among the lessons of this vagrant history of decapitation and display is the ease with which such ‘lumps of matter’, which once were parts of people, may be incorporated into daily life. Whether as ritual object, anthropological specimen, grisly aide-mémoire or (amazingly) domestic gewgaw, the severed human head has served many purposes. It is, says Larson, ‘simultaneously a person and a thing’. In fact, as Julia Kristeva has argued in her book The Severed Head, decapitation (real or imagined) might be the inaugural act that allows humans to think of each other as mere objects in the first place, or to imagine themselves as inanimate, disarticulate, doll-like beings.

How does a cultural historian come to work such a dismal, blood-soaked patch? Larson became interested in her subject while working at the Pitt Rivers Museum in Oxford, where she observed visitors’ reactions to the ten shrunken heads displayed there. Some of these may in fact be fakes: monkey or sloth heads reduced and remodelled to fool Victorian curio hunters. Even so, they are part of a history that museum-goers who gasp and go ‘Ewww!’ before them do not always notice. Head-hunting raids were rare and ritually circumscribed in Ecuador and Peru until Europeans took an interest. Thereafter, as Larson puts it laconically, ‘supply rose to meet demand’. The pattern was repeated elsewhere: heads were traded for guns, with which hunters procured more heads and often killed women and children for the first time. The most grotesque of Larson’s anecdotes from this period concerns one James Jameson, a naturalist in Henry Stanley’s equatorial party, who in 1890 paid African soldiers to kill and cannibalise a girl while he watched, sketchbook in hand. He was also said to have had the head of a murdered man shipped home and stuffed for domestic display by a taxidermist in Piccadilly.

Jameson’s tale is emblematic, in part because of the public horror that greeted accounts of his grim antics. Mostly, people have found decapitation quite acceptable in limited circumstances, only objecting to the act or the spectacle when it seemed to be flaunted a touch too cruelly. The trophy hunting of American soldiers during the Second World War is a case in point. Larson has read numerous diaries and letters in which men serving in the Pacific admit to boiling Japanese heads in oil drums, bleaching skulls to make candlesticks or amusing themselves by tossing pebbles into the open cranium of a dead enemy. Many cleaned, painted or jauntily inscribed skulls (‘This is a good Jap!’) were sent home as souvenirs, but it was only in 1944, when Life magazine published a photograph of some GI’s sweetheart with a skull grinning away on her writing desk, that the army and the government publicly deplored the habit.

Photography played a part, too, in the eventual hiding away of the work of the guillotine, French crowds in the early 20th century proving horribly eager to get a snapshot of the decisive moment. Joseph-Ignace Guillotin’s contrivance provides Larson with her most alarming chapter, on the still-unanswered question of how long, if at all, a severed head may live. The inventor had declared: ‘With my machine, I can make your head roll in the blink of an eye and you do not suffer.’ But witnesses to the Terror began to report unsettling interludes in which the detached head still twitched and even responded to stimuli: Marat’s assassin, Charlotte Corday, was said to have flushed with anger when the executioner lifted up her head and gave its face a slap. In the early years of the 19th century, physicians made several studies at the foot of the scaffold, pricking severed heads with scalpels or shouting in the ears, ‘Do you hear me?’ Of course, none responded, but the occasional muscle contraction kept the mystery alive.

Such experiments lead Larson swiftly on to the morbid quackery of cryonics: heads deep-frozen – ‘neurosuspended’, in the hopeful jargon – inside giant Thermos flasks somewhere in Arizona. But she might also have considered the strange craze for living-head movies in the decades after the Second World War: films with such titles as They Saved Hitler’s Brain and The Brain that Wouldn’t Die, in which a crazed or tormented remnant has revenge on the full-bodied. (The heads often possess telepathic powers, which neatly solves the narrative problem of their not getting about much.) Larson is less apt than Kristeva to theorise about the desire to gaze upon a severed head, even when she turns inevitably to reflect on the millions who by now have watched terrorist beheading videos online. It’s a desolate thought, but maybe the frankly absurd living-head films of the 1950s and 1960s offer a clue to contemporary viewers’ urges: empathy and horror aside, some part of some of us expects to find a kind of comedy there.