A Smart Book on Taste: John McQuaid's Tasty

Illustration: Tomi Um

There’s a commonly held belief—espoused in high school biology classes and wine-tasting seminars—that different parts of the tongue hold particular types of taste receptors. Sweet’s in front, bitter’s in back, sour and salty sit in between. That concept turns out to be completely false, writes John McQuaid in his new book, Tasty: The Art and Science of What We Eat. In reality, the receptors on our tongues are spread around more or less evenly.

McQuaid’s latest falls squarely in the “Why X Explains the World” popular-science genre. The human sense of taste, McQuaid argues, has largely determined who we are today: a restless, curious, clannish species that has the run of the planet, suffers from high rates of obesity and diabetes, and groups itself according to our individual mealtime preferences. (My mother, who grew up eating daily doses of kimchee in Korea, was horrified the first time she encountered cheese.)

Even though taste has kept countless animal species alive, researchers have traditionally dismissed it as the crudest and least interesting of the senses. And yet it has the power to create giant multinational food conglomerates, enforce social norms, and shorten human life spans. “More than vision, or hearing, or even sex, flavor is the most important ingredient at the core of what we are,” McQuaid writes. “It created us.”

A Pulitzer Prize-winning science journalist whose previous book was about superstorms and Hurricane Katrina, McQuaid fortunately doesn’t spend much time litigating his point. Instead, the book is mostly an exploration of taste in all its complexity and contradiction.

You’ll learn, for instance, that recognizing bitterness has been more crucial to the development of advanced life-forms than recognizing any other flavor. So we’re very attuned to it: The human mouth has only three types of receptors for sweetness but 23 for bitterness. Taste developed as a primitive aversion-attraction binary that helped the earliest organisms find (sweet) sustenance and avoid (bitter) poisons—jellyfish, fruit flies, and even bacteria can recognize bitter compounds, which is why they’re still around today. (Then again, so are whales and dolphins, whose taste buds can only sense saltiness.)

Taste, he shows, drove the domestication of animals and new technologies such as fire: Without the tenderizing power of flame, it would take eight hours of chewing to consume a modern meal.

Entrepreneurs, naturally, are trying to crack taste’s codes. McQuaid points to Opertech Bio in Philadelphia, which trained an army of rats in the mid-2000s to identify promising new flavor formulations and then test the palatability of compounds. Another, Senomyx, goes even further, growing taste receptors in petri dishes. There’s also the Chicago molecular gastronomist Homaro Cantu, who’s trying to create a line of healthy, low-sugar pastries. He’s playing around with the extract of a West African shrub, Synsepalum dulcificum, which tricks the tongue into thinking sour tastes are actually sweet.

McQuaid is a deft writer with a talent for vivid metaphors, and what he leaves you with most is a sense of all that remains unknown. In one of the most interesting chapters, he looks at the quandary of why human beings seem to take pleasure in eating painfully spicy food. Research has suggested it might be a way to feed the human hunger for risk and arousal without the downside of actual bodily harm.

There are deeper mysteries, too. It turns out we have taste receptors not only in our mouth, but also throughout our entire body. Because we can’t consciously “taste” things once we’ve swallowed them, no one knows exactly what those receptors are for. “Flavor, in other words, is only the capstone of a vast, hidden system,” McQuaid writes. “It starts in the mouth with a burst of deliciousness, then disappears in darkness down into the gut, and from there its hand reaches everywhere in the body.” It’s something to ponder, if not at dinnertime. 

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