Free Gulp: Adventures on the Alimentary Canal by Mary Roach

food.)
    “So somebody,” I observe, “could do a taste test with various salivas.”
    “If somebody would like to do that, yes.”
    Somebody—really everybody—wouldn’t. I point to the beaker labeled E . “What about just your own? Would you ever—”
    “No, I wouldn’t. Even me. Although actually, you are drinking it all the time.”
    “Right, so—”
    “ No .”
    An intriguing double standard applies to your own saliva. As long as it stays in your mouth, it’s benign, welcomed even, no more offensive than the water it tastes like. Outside your mouth, it’s almost as vile and contemptible as a stranger’s. As part of a study, our friend from the University of Pennsylvania psychology department, Paul Rozin, asked subjects to imagine a bowl of their favorite soup and to rate their liking of it. He then asked them to rate that same bowl of soup after they’d imagined spitting into it. Forty-nine out of fifty subjects lowered their rating. Among certain castes in India, writes Edward Harper in “Ritual Pollution as an Integrator of Caste and Religion,” spitting on someone puts even the spitter “in a state of severe impurity,” because it is assumed that some of his saliva has “rebounded onto him.”
    The saliva taboo can make life burdensome for researchers. Silletti’s colleague René de Wijk did a study years ago that looked at how the salivary breakdown of starch mobilizes fats and enhances flavor. (Fat is the main carrier of flavor.) To do this study, he needed his subjects to rate the taste of custard samples with and without a drop of their saliva added. You can’t just have them spit in it, he explained, because then they won’t go near it. He had to collect samples of their saliva without telling them why, and then add it behind their backs, like a spiteful waitress.
    The same double standard applies to all “body products,” as Rozin calls them, managing to make snot and saliva sound like spa purchases. We are large, mobile vessels of the very substances we find most repulsive. Provided they stay within the boundaries of the self, we feel no disgust. They’re part of the whole, the thing we cherish most.
    Paul Rozin has given a lot of thought to what he calls the psychological microanatomy of the mouth: Where, precisely, is the boundary between self and nonself? If you stick your tongue out of your mouth while eating and then withdraw it, does the ensalivated food now disgust you? It does not. The border of the self extends the distance of the tongue’s reach. The lips too are considered an extension of the mouth’s interior, and thus are part of the self. Though culture shifts the boundaries. Among religious Brahmin Indians, writes Edward Harper, even the saliva on one’s own lips is considered “extremely defiling,” * to the extent that if one “inadvertently touches his fingers to his lips, he should bathe or at the least change his clothes.”
    The boundaries of the self are routinely extended to include the bodily substances of those we love. I’m going to let Rozin say this: “Saliva and vaginal secretions or semen can achieve positive value among lovers, and some parents do not find their young children’s body products disgusting.”
    I recall being told, in grade school, that Eskimos kiss by rubbing noses. Is this an example of a culture reluctant to accept the saliva of a loved one? Gabriel Nirlungayuk, my go-to man for all things Eskimo/Inuit, confirmed that the kunik , or nose rub, has been and remains the traditional alternative to the kiss. “Even to this day, now that my children are adults, I kunik them when I have been away for a long time.” But never girlfriends. By the time Nirlungayuk was a teenager, kissing “whiteman’s way” had caught on. Nobody seemed to have a problem with extending those boundaries. If anything, the Inuit are leaders in the field. “Sometimes when my ingutaq— granddaughter—is full of snot, my wife or myself will wipe it