Noah Whiteman (Oneworld (UK); Little, Brown (US))
EVERY morning, millions of people rub their bleary eyes and stumble as quickly as they can towards the nearest source of coffee. The urge to get a caffeine hit is so overpowering, and the reward for it so great, that we often forget we are hankering for a fundamentally bitter chemical.
That bitter taste is meant to be unpleasant, a warning that we are consuming something potentially dangerous, says , an evolutionary biologist at the University of California, Berkeley, in his book Most Delicious Poison: From spices to vices 鈥� the story of nature鈥檚 toxins. We may tend to ignore it, but our bodily alarm system has been tripped because caffeine is a plant-derived poison, sharing a lineage with such ugly customers as the atropine in deadly nightshade and the coniine in hemlock.
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In his book, Whiteman covers these and other plant toxins, though you might be surprised by how few you recognise as such, given that their effects in humans are varied and sometimes positive. Still, he argues that compounds we are familiar with as spices, stimulants and even medicines are just moonlighting in those roles, having been lifted from nature鈥檚 toxic battlefield. The original purpose of caffeine, the capsaicin in chilli peppers and the opioids we have adapted for pain relief was to 鈥済ain the upper hand, through offense and defense, in the Darwinian struggle for existence鈥�.
The main players in this struggle are plants and herbivorous insects, and Whiteman calls on a wealth of examples to explain how their constant adaptation to one another drives the evolution of more toxins with new and varied effects. These can be straightforward: the pyrethrins in chrysanthemum flowers can cause 鈥渋nvoluntary muscle contractions, paralysis, and even death鈥� for many insects, he writes. But there are subtler and more selective toxins. The flowers of Rhododendron ponticum, for example, are 鈥減oisoned chalices鈥� that deter most insect species, while sparing the northern European bumblebee due to its role as a pollinator.
In each chapter, Whiteman explores new categories of toxin 鈥� from alkaloids like caffeine and quinine to the tannins in red wine 鈥� teasing out the lessons each brings. The gritty mouthfeel of some wines, for instance, is a sign of our evolutionary adaptation to eating tannic plants, as salivary proteins bind to the tannins and take them out of commission before they can reach the liver, where they would do us harm.
Whiteman unravels how it is that plants, our distant evolutionary cousins, are able to target Achilles鈥� heels in human biochemistry. Digoxin in white foxglove, for example, binds to a specific site on a protein called a sodium-potassium pump, slotting into it 鈥渁s a hand fits into a glove鈥�. At high doses, this causes a catastrophic drop in blood pressure, but it can also be used in medical preparations to treat heart conditions.
Whiteman also explores a wholly different Achilles鈥� heel: the human propensity for addiction, centring this on the death of his father from complications of alcohol use disorder. Spurred by this, he explores the mechanisms that predispose some people to misuse psychoactive substances, many of which, such as nicotine, are plant toxins.
If that wasn鈥檛 enough, he also weaves in a history of the societal impact that toxins have had. From the spice trade in the Moluccas in what is now Indonesia to the plundering of the Amazon, their use has been defined by exploitation of Indigenous peoples.
Those living in the Amazon basin, for example, were never compensated for the sophisticated knowledge they passed to Westerners about curare, a toxic preparation that colonisers and settlers called 鈥渇lying death鈥�. Yet the tubocurarine within found profitable use during the 20th century as a muscle relaxant during surgery.
This makes for a lot of intertwining threads in the book and, at times, it can be difficult to follow what Whiteman is building to. However, his passion and depth of knowledge shine through, making this well worth a read. So, spare the time to mull over each chapter for slightly longer than you might otherwise, if just to let the poison sink in.
