The aroma of cinnamon and nutmeg smells like sweet autumn nostalgia in the US, but the real story behind pumpkin spice is far spicier.

Long before I'd ever sipped a pumpkin spice latte, I was in love with pumpkin spice. As a student in London, I waited eagerly for autumn, when auburn leaves crisped underfoot and my American flatmate prepared her annual Thanksgiving feast. The kitchen was redolent with the American spice mix – a blend of nutmeg, ginger, cinnamon and clove – and a parade of hearty dishes emerged. My favourite was the pumpkin pie; sweet, spicy comfort on a fork.

My youthful encounter with that fragrant spice blend was, of course, hardly the last. In the years since, pumpkin spice has metamorphosed from a simple seasoning into a full-blown national obsession. Americans splash out $500m annually on pumpkin spice-flavoured foods, while spending on pumpkin spice products escalates every year, with the industry slated to more than double in size by 2035.

Americans insist it wasn't always this way. "I only remember [pumpkin spice] as the key flavour in pumpkin pie, and we'd make it once a year for Thanksgiving," says culinary scientist and author Jessica Gavin. That changed in the early 2000s, when the "Pumpkin Spice Latte" suddenly appeared on everyone’s radar.

Blame Starbucks (many do); its 2003 introduction of the PSL (Pumpkin Spice Latte) is credited with igniting pre-Thanksgiving pumpkin spice consumption while cementing the combo as the American shorthand for autumn.

But how did pumpkin spice become synonymous with US culture when nutmeg, ginger, cinnamon and clove are indigenous to Asia?

The answer lies in the dark history of colonialism.

To trace that story, we have to look far from the US to the islands where the world's most coveted spices first grew.

Though the Asian spice trade had existed peacefully for centuries, it would turn deadly during the conquest of the New World. In 1621, the Dutch, desperate for a monopoly over the expensive, rare nutmeg that grew only in Indonesia's Banda Islands, would annihilate nearly the entire Bandanese population, keeping the rest in near-slavery, while selling the spice for massive profits in Europe. In Sri Lanka, home of the cinnamon plant, the Portuguese, Dutch and English forced locals into harvesting and peeling cinnamon under brutal, exploitative conditions; those who resisted were flogged and tortured. Cloves from Indonesia’s Ambon Islands were gathered under the same Dutch regime; while ginger, introduced to the Caribbean in the 17th Century, was cultivated on plantations where the English, Spanish and French relied on enslaved labour.

Meanwhile, across Europe, those same spices became synonymous with celebration and comfort, used to flavour meat and "baked dishes such Christmas cake or the British figgy pudding", says food historian Dr Ashley Rose Young. "North America was colonised by many different European groups, so the US in its early iterations had many British influences. That included making heavily spiced ginger cake and other heavily spiced dishes in the holidays."

As Americans developed their own cuisine, those holiday traditions of spiced, sweet dishes persisted. "Citizens started to develop their own cuisine to distinguish themselves from their colonial overlords, including recipes that used local squash like pumpkin," says Young.

In 1796, Amelia Simmons's American Cookery was the first to list nutmeg, ginger and allspice as ingredients in "pompkin pie"; and with the rise of "convenience cooking" in the late 19th and early........

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