Thursday, May 30, 2019

The Omnivore's Dilemma

No, not the book of that name, which was the only reference that popped up on a full page of Google results. I first encountered this term in the section on "Disgust" in HOW THE MIND WORKS, by Steven Pinker, who attributes it to psychologist Paul Rozin. The omnivore's dilemma encapsulates the double-edged nature of our ability to digest a vast variety of different foods. Therefore, human beings can survive in almost any environment on Earth. The negative side of this advantage is that we can't be sure whether a new potential food source is safe to eat until we've tried it.

As Pinker puts it, "Disgust is intuitive microbiology." After a certain age (when they outgrow the "put everything in their mouths" phase), children avoid things we would consider intrinsically disgusting, such as decayed organic matter or body fluids and excretions. Most people will even refuse to put in their mouths harmless items that resemble disgusting objects (e.g., fake vomit). Contact or resemblance equals contagion, an emotional aversion that overrides mere rationality. But what accounts for "disgust" reactions to items that we dismiss as inedible but many other cultures classify as food?

Pinker points out that we accept a very narrow range of animal products as food, even though those we shun are perfectly edible. Most Americans confine their animal diets to chickens, pigs, cattle, sheep, and selected types of fish and other seafood. From the mammals we raise for food, many of us eat only certain parts of their bodies and avoid the rest (e.g., organ meats, feet, tails, etc.). Pinker discusses how we learn these dietary prejudices as a byproduct of the omnivore's dilemma. In infancy and early toddler-hood, the "put everything in their mouths" stage, children have to eat what their parents offer them. When the child gets mobile enough to forage for himself or herself (in a hunter-gatherer society), the "picky" stage sets in. (It's probably not a coincidence that the food-finicky phase coincides with the drop in appetite when the rapid growth spurt of early life slows down.) Now the child regards new foods with suspicion. The items fed by the parents during the early months are accepted as edible. All other potential foods are, by definition according to the child's world-view, repulsive. Whatever isn't explicitly permitted is forbidden and therefore disgusting. As a practical corollary of this process, it seems parents should try to introduce their toddlers to as many different foods as possible during the sensitive learning period.

I was reminded of this section in HOW THE MIND WORKS (a fascinating, highly readable book—check it out) by Facebook videos of our seven-month-old grandson trying his first solid foods. He likes avocado. Until recently, he liked applesauce. Last week, he rejected it; maybe that's just a temporary fluke. Babies, like human beings in general, crave sweet tastes, because in a state of nature our ancestors depended on sweetness to tell them when fruit was edible. This natural attraction to sugar inspires infant-care experts to advise starting babies on less sweet foods (e.g., vegetables) first, rather than letting them get fixated on sugary things such as fruit right off the bat.

Pinker, by the way, says that not only are most parts and products of animals considered disgusting (see above), but also most or all disgusting things come from animals. Vegetables may be rejected because they taste bitter, but they're not viewed as disgusting. I reacted to that statement with, "Speak for yourself, Dr. Pinker." As a child, I was disgusted—i.e, nauseated—by several kinds of vegetables because they were served in a cooked-to-mush condition. The combination of change in taste from overcooking and the yucky texture made my stomach revolt. I believe, by the way, that the cliche of children hating vegetables arises from the crimes perpetrated on perfectly harmless plants by 1950s cooking styles and the prevalence of over-processed canned veggies in the American diet of that period.

One especially interesting issue: What about bugs? Why don't many cultures—ours included—eat insects and similar arthropods (e.g., spiders)? We often pay high prices for the privilege of consuming certain other arthropods, such as lobsters. And we happily eat one kind of insect secretion (honey). Yet we abhor the termites and grubs that form an important part of our ape relatives' diets. The easy answer in American culture is that bugs aren't included among the "permitted" items we're fed in childhood. But why aren't we?

An article from SCIENTIFIC AMERICAN attempting to answer that question:

What's Stopping Us from Eating Insects?

And one from the anthropology website "Sapiens":

Why Don't More Humans Eat Bugs?

Neither of these articles exactly repeats Pinker's hypothesis, which makes a lot of sense to me, although the second essay touches upon it: Gathering enough insects or other small arthropods to provide sufficient protein isn't a very efficient process. It takes a lot of time and energy. Therefore, people incorporated bugs into their diets only if those creatures were abundant (in the tropics, for instance) and nothing better was readily available. Where a society could obtain plenty of protein from more efficient sources, such as raising herd animals, they didn't bother to eat bugs. And since whatever isn't permitted during the early learning period is by definition forbidden, bugs are disgusting to most of us. This cultural phenomenon drives the humorous appeal of the popular children's novel HOW TO EAT FRIED WORMS, since at a certain age many kids develop a sort of queasy fascination with yucky things.

One lesson for future interplanetary explorers might be that colonists should conscientiously expose their children from infancy to all sorts of safe native foods in extraterrestrial environments, even if the parents find those items repugnant.

Margaret L. Carter

Carter's Crypt

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