From the forces behind devastating natural disasters to what’s best for women’s health, religion is frequently called upon to answer questions better left to science. But in a refreshing turnabout, some religious leaders are seeking advice from scientists. Three rabbinical experts from the Orthodox Union recently asked researchers from the American Museum of Natural History in New York City for help with a problem: Are the parasitic worms that turn up in fish roe and canned sardines kosher?
For those of us who don’t keep kosher, the matter may seem trivial. (Being grossed out by parasitic worms in your food is a different issue). But whether something conforms to Jewish dietary laws — kosher means “fit” or “appropriate” — is big business. Estimated sales of kosher-certified food in the United States were $12.5 billion in 2008. And marketing research suggests that the kosher slice of the consumables pie is only getting larger. Less than half of kosher products are bought by people who identify as Jewish. Muslims, vegetarians and lactose-intolerant consumers also look for the kosher label, as do a growing number of people who perceive kosher food as being better for you — and safer. You might guess that certified food producers include outfits like Zabar’s, Cohen’s and Soy Vay (a company that makes dressings, sauces and marinades). But Orthodox Union Kosher, the world’s largest certifying organization, also certifies Glenmorangie, Tom’s of Maine and the pharmaceutical giant Merck.
Kosher law is based on religious precepts — primarily the Torah, the first five books of the Bible — but it has little to do with blessings. Rather, it is concerned with the kosher status of food ingredients, the avoidance of forbidden food mixtures, and how said food is prepared. And while applying religious precepts and beliefs to determine what one eats may seem arbitrary, the approach has a kind of scientific resonance. There’s no gestalt, no “I know it when I see it,” to kosher law. “It is, above all, an internally consistent logical system that can be applied to new situations and technologies,” writes Zushe Yosef Blech in the 2009 edition of Kosher Food Production.
That said, the application of kosher law in the modern age isn’t always easy. Birds have long been problematic, as the Bible doesn’t detail signifying features of kosher fowl; it provides only a list of 24 species that are not kosher. When Jews came to the Americas and encountered the Muscovy duck, a species for which there was no settled tradition, an acrimonious, centuries- long debate ensued. Foods that employ technological advances, such as jelly beans and other sweets that are coated with lac resin — the oozy secretion of several species of insects — also pose problems. Here rabbis may use “if it walks like a duck,” or in this case a bee, reasoning. Even if the insects aren’t kosher, their secretions can be, like honey from bees.
Fish have always been relatively straightforward. Kosher fish have fins and scales, a scale being a fingernail-like growth that is removable without damage to the skin. So unlike catfish and sturgeon (no scales), the canned sardines and capelin roe brought to the American Museum were decidedly kosher. The scientists, led by leech expert Mark Siddall, had to determine whether the parasitic worms that were commingling with the fish and eggs were kosher.
Parasitic worms on their own are not kosher. So what made these parasitic worms different from all other parasitic worms? What concerned the Orthodox Union was whether these worms could be considered part of the fish. Before Louis Pasteur definitively debunked spontaneous generation in 1859, worms found in the flesh of fish were thought to arise from the fish itself and thus were kosher. Worms found in the fish intestine were presumed to have been eaten by the fish and therefore not kosher. Siddall and his colleagues had to determine what species of nematode were present and whether their life cycles entailed intestinal or nonintestinal dwelling.
A DNA analysis by the researchers revealed at least four species of parasitic nematodes (perhaps a fifth species — nematode taxonomy is still a work in progress). Given what’s known about their life cycles, none are thought to spend time in the intestines.
“Whereas the increased prevalence of nematodes in these samples might be alarming and perhaps unsightly, the products nonetheless were kosher and there was no evidence of any failure to adhere to food preparation practices consistent with Orthodox Judaism,” Siddall and colleagues write in a paper to appear in the Journal of Parasitology.
Phew. Now wouldn’t it be swell if science were called upon more often to offer expertise in areas where it, well, has expertise? After all, there’s no good reason why scientific knowledge shouldn’t always be kosher.