A less lethal and more entertaining swallowing misstep is nasal regurgitation. Here the soft palate—home turf of the uvula,* that queer little oral stalactite—fails to seal the opening to the nasal cavity. This leaves milk, say, or chewed peas in peril of being horked out the nostrils. Nasal regurgitation is more common with children, because they are often laughing while eating and because their swallowing mechanism isn’t fully developed.
“Immature swallowing coordination” is the reason 90 percent of food-related choking deaths befall children under the age of five. Also contributing: immature dentition. Kids grow incisors before they have molars; for a brief span of time they can bite off pieces of food but cannot chew them. Round foods are particularly treacherous because they match the shape of the trachea. If, say, a grape goes down the wrong way, it blocks the tube so completely that no breath can be drawn around it. A child is better off inhaling a plastic barnyard animal or toy soldier, because air can be inhaled through its legs or around its rifle. Hotdogs, grapes, and round candies take the top three slots in a list of killer foods published in the July 2008 issue of the International Journal of Pediatric Otorhinolaryngology, itself a calamitous mouthful. Jennifer Long, a professor of head and neck surgery at the University of California, Los Angeles, went so far as to declare hotdogs a public health issue. A candy called Lychee Mini Fruity Gels has killed enough times for the U.S. Food and Drug Administration to have banned its import.
Every now and then a food comes along that is so difficult to orally process that even healthy adults without dysphagia have trouble getting it down. Sticky rice mochi, a traditional Japanese New Years food, kills about a dozen people every year—along with puffer fish and flaming cheese, the world’s riskiest menu items.
The safest foods, of course, are those that arrive on the plate premoistened and machine-masticated, leaving little for your own built-in processor to do. They are also, generally speaking, the least popular. Mushy food is a form of sensory deprivation. In the same way that a dark, silent room will eventually drive you to hallucinate, the mind rebels against bland, single-texture foods, edibles that do not engage the oral device. Mush is for babies. Those who can, want to chew. The story of U.S. military rations bears this out. During World War II, when combat rations were tinned, meat hashes were a common entrée because they worked well with the filling machines. “But the men wanted something they could chew, something into which they could ‘sink their teeth,’” wrote food scientist Samuel Lepkovsky in a 1964 paper making the case against a liquid diet for the Gemini astronauts. He summed up the soldiers’ take on potted meat: “We could undoubtedly survive on these rations a lot longer than we’d care to live.” (NASA went ahead and tested an all-milkshake meal plan on groups of college students living in a simulated space capsule at Wright-Patterson Air Force Base in 1964. A significant portion of it ended up beneath the floorboards.)
The only thing sadder than swallowing mush is not swallowing at all. Tube-feeding is a deeply depressing state of affairs. Rather than chew and spit out his food, Tom Little—the Irishman with the strictured esophagus—could have mashed it and pushed it directly into his stomach. In fact, he tried this, but without chewing, it “failed to satisfy.” (Beer, however, was poured directly into the funnel.) Here’s how badly people want to chew. Recall that dysphagia may knock out the reflex that repositions the larynx (voice box) to allow food into the esophagus. Jennifer Long told me these patients have on occasion asked to have their voice box surgically removed so they can swallow again. In other words, they would rather be mute than tube-fed.
Crispy foods carry a uniquely powerful appeal. I asked Chen what might lie behind this seemingly universal drive to crunch things in our mouths. “I believe human being has a destructive nature in its genes,” he answered. “Human has a strange way of stress-release by punching, kicking, smashing, or other forms of destructive actions. Eating could be one of them. The action of teeth crushing food is a destructive process, and we receive pleasure from that, or become de-stressed.”
I run this by René de Wijk when I get back to his house in the evening. He is slouched on the sofa, his frizzy hair falling in clumps on his forehead. His son sits between us, playing Assassin’s Creed on the TV screen. A man in a cowled robe is doing some de-stressing, bludgeoning people and slicing them in two with a broadsword.
René agrees with Chen’s assessment. “With crispy, it’s so obvious that you’re destroying the food in order to get your sensation. What is more marvelous than to control a nice structure with your mouth?” René doesn’t know offhand of any studies on the psychology of crunchy food, but he promised to e-mail a colleague, Ton van Vliet, a food physicist who has devoted the past eight years of his career to a deeper understanding of crispy-crunchy.