From time to time, politicians and other rulers-of-men like to categorize the natural world not according to biology, but rather for convenience or monetary gain. Take, for example, the tomato. The progenitor of ketchup is a seed-bearing structure that grows from the flowering part of a plant. It is, by definition, a fruit. In 1893, however, the US Supreme Court ruled in the case of Nix v. Hedden that the tomato was a vegetable, subject to vegetable import tariffs. Even if the tomato is, technically, a fruit, it tends to be treated in American cuisine as a vegetable, wantonly littering our salads with its jelloey gooeyness.
Corn and rice are another good example. The Bible forbids Jewish people from eating chametz - foods made from wheat, barley, spelt, rye, or oats - on Passover. Ashkenazi Jews consider corn, rice, and legumes, a class of foods called kitniyot, as forbidden on Passover as well. It isn't that they're forbidden, per se, but that they're easily confused for the real thing. As I learned in my high school Talmud class, the medieval Rabbis decided to forbid these not-technically-forbidden grains because of a principle called marit ayin, which literally means "what it looks like." The Wikipedia explanation is quite good: "While not against the laws of passover to consume kitniyot, a person might be observed eating them and thought to be eating chametz despite the law, or erroneously conclude that chametz was permitted. To avoid this confusion, they were simply banned outright."
Still, neither the Supreme Court's reclassification of the tomato is a fruit, nor the medieval Rabbis' designation of corn and rice as forbidden grains, is the most amusing example of non-scientific categorization. The Catholic Church has them all beat.
There were once between 60 and 400 million beavers (Castor canadensis) occupying the rivers and streams of North America, from the great white north to the deserts of northern Mexico. Then the Europeans came. With them came disease along with an insatiable desire for beaver pelts and for beaver castoreum, a urine-like secretion often used in perfume and cologne. Combined with the once-sustainable hunting of beaver by indigenous North Americans for their meat, the beaver population rapidly declined. (The species is now rebounding, thanks to trapping regulations, and now includes some 6 to 12 million individuals)
In addition to disease, the European settlers also brought Catholicism with them, and successfully converted a large proportion of the indigenous population. And the native Americans and Canadians loved their beaver meat.
So in the 17th century, the Bishop of Quebec approached his superiors in the Church and asked whether his flock would be permitted to eat beaver meat on Fridays during Lent, despite the fact that meat-eating was forbidden. Since the semi-aquatic rodent was a skilled swimmer, the Church declared that the beaver was a fish. Being a fish, beaver barbeques were permitted throughout Lent. Problem solved!
The Church, by the way, also classified another semi-aquatic rodent, the capybara, as a fish for dietary purposes. The critter, the largest rodent in the world, is commonly eaten during Lent in Venezuela. "It's delicious," one restaurant owner told the New York Sun in 2005. "I know it's a rat, but it tastes really good."
And it's not just oversized rats that make for good eating in the run up to Easter, either. I have it on authority from my cousin Jerome (who knows everything) that "iguana tail soup is a fave for Lenten meals in Nicaragua." Yum.
For more on beavers:
For more on bad taxonomy:
For more on dietary traditions during Lent:
Naiman R.J., Johnston C.A. & Kelley J.C. (1988). Alteration of North American Streams by Beaver, BioScience, 38 (11) 753-762. DOI: 10.2307/1310784