“Fish is brain food.”
“Fish will make you cold and slow and will block medicine power.”
“If it doesn’t have fins and scales, it is unclean.”
Don’t compliment a baby or you will bring down the evil eye. Don’t sit so that the sole of your shoe or the bottom of your foot is pointed at someone. Don’t touch someone on the head lest you interfere with their chi. Don’t eat within one hour before going swimming. Women shouldn’t bathe during . . .
Every culture has things that Must Not Be Done. Some of them seem odd to outsiders, and on occasion, even those inside the culture can’t explain precisely why you Don’t Do That. When anthropologists and folk-lore students start finding patterns, well, then it gets interesting.
Many Plains Indian peoples had taboos about fish – don’t eat them. Either they are just bad luck, or their are bad for medicine power, or they will make you slow, or . . . Up and down the Great Plains of North America, freshwater fish were taboo. Which made ethnographers wonder what the connection was, since these groups all moved to the Plains at different times, and had somewhat different cultures. What probably made fish bad news was the lack of fat. Most parts of the Great Plains, especially the western parts, lack carbohydrates but have lots of lean-meat protein sources. Eating too much lean meat without access to fats and carbohydrates can lead to medical problems, and that may be the origin of the prohibition. Season-dated Paleoindian bison kills show a preference for females in the fall (when they are fattier than males), but males in the spring (when females are far leaner than males.) Some archaeologists have speculated that rules of hunting might have included taboos, although we can’t tell.
The Jewish and Muslim rules about not eating pork are probably the best known food taboos in the western world, although they are not identical. Jewish rules hold pork to be unclean, but pigs may be raised and sold to outsiders. In an emergency, pork may be consumed if the alternative is starvation. Finding a package of bacon on the front step of a synogogue does not render the place of worship ceremonially unclean. The same is not true of a mosque. Pork and pigs are abominations in Islam, and are to be avoided at all costs.
Many food-related taboos are tied in with ideas of ritual purity and cleanliness. Insects and things that creep on the ground may be “dirty.” Likewise many cultures have a ban on consuming carrion eaters, because they eat decayed (and thus corrupt and unclean) flesh. For the Comanche, fish are unclean, and they won’t eat dog because Coyote is close to dogs. Other Indian peoples have no problem with consuming dog meat (the Cheyenne and Maya, for example) but the Kiowa eschew bear meat.
Ritual cleanliness also places a lot of limitations on women of child-bearing age. A woman having her menses is often ritually unclean, or might have the unfortunate ability to break medicine-power or certain blessings. In some cases, women were strictly confined away from sunlight and the rest of society, under the strict care of a post-menopausal woman, until their cycle had finished. In other cultures, the rule was that women of child-bearing age could not go near where the shaman or medicine man lived. Sometimes, women were to avoid hunters for a set number of days before a major hunt, to ensure that hunting magic would remain strong, and that the “scent” (real or spiritual) of blood would not contaminate the hunters and scare away the game.
Some cultures have a lot more taboos than do others. Entire slices of society might be under strict limitations because of a caste system, to the point that if the shadow of a certain person touches the possessions of a different person, the offender is to be executed for polluting the one of higher rank or spiritual authority.
The west doesn’t have as many religious taboos as many cultures, although we certainly have unspoken customs and limitations. Don’t talk about your income or job. Don’t tell dirty jokes or swear in mixed company. Certain cuts of clothing are not suitable for daytime or business attire. Don’t forget to leave a tip for a waiter or waitress, unless the service has been truly terrible. Men should remove their hats when entering a place of worship unless that faith requires the head to be covered. Don’t talk about sex, religion, or politics at the supper table. (Note that “religion” can include college or professional athletics in some parts of the country.)
And never, ever comment on a no-hitter baseball game in progress, or a smooth ride on a flight, or say anything like, “Boy, this equipment test is going really well!” Every fan, pilot, and tech or engineer will turn well-deserved wrath upon thee.
For an intriguing academic look at food taboos around the world:
Cat Rotator's Quarterly 
Don’t forget “knock on wood”.
That one still exists. 😀
As a bald guy, I fullheartedly agree that the tops of people’s heads should not be touched. I don’t know about chi, but it makes me markedly less sanguine.
Don’t ever say the words “quiet” or “slow” in an Emergency Room.
Don’t speak of good fortune, or it will go away.
Don’t speak of your fears, lest you invite them.
One wonders just where Murphy fits in the realm of Heaven, or more likely Pandaemonium.
IMO The Trickster (and Murphy is one of his names) is one of the Great Author’s agents in keeping Humans humble.
Anytime some human thinks that “he has a perfect plan” then the Trickster shows the human the flaws in his plan. 😀
Of course, sometimes the Trickster cause “accidents” that help out somebody facing terrible odds. 😉
I’ve also heard that there was a good reason for the pork prohibition among Jews and Muslims: trichinosis, which can be contracted from badly cooked pork, is common in pigs in the Mideast/Asia Minor/North Africa region.
About these food taboos that supposedly have solid medical reasons behind them, one question that I always wonder about is “how did tribes/peoples that supposedly had no knowledge of medicine and (for North American Amerinds) no method of transmitting information besides oral histories ever figure out these issues?” Especially the freshwater-fish thing: if fish was only one of several sources of high-protein-low-carb meat in use, how could they ever make the connection between specifically “we’re eating too much fish” and the resulting physical problems?
The typically religious part is going from “Don’t eat too much fish,” to “Don’t eat any fish.” People always seem to take things too far. As the Hindu worship of cows as a great source of food to, well, what it is now. Buddha’s great teaching was “All things in moderation,” which seems to have fallen on deaf ears. Christ’s simple parables were routinely misunderstood or not comprehended at all, even by his chosen disciples. And then there’s veganism, and the people who inflict it upon their children and pets.
Trichinosis, as it turns out, requires a comparatively temperate climate to become a problem. You have to get up into the Mt. Lebanon region and the highlands, up into the Atlas Mountains, and so on before you see much of it. But pigs do not fit a nomadic life like that described for the Patriarchs. When you read about the Children of Israel up until Judges, most of them were basically Bedouin, with a few settled groups. So if deep-seated taboos form early in a culture, 1) the high consumption of pork by Egyptians and 2) the inability for “our kind” to rear pigs makes “we don’t eat pigs” a logical development. Islam takes that and intensifies it, as it does with alcohol. “Don’t drink alcohol in excess” becomes “don’t drink anything fermented for more than three days. At all.”
“Don’t touch children on the head lest you interfere with their chi.” Is or was actually in the country brief for Thailand for years and that was a quick way to piss off the Thai people!
Pigs are also extremely hard on desert or marginal environments and are impossible to keep completely confined. That would make raising them ill advised in most middle eastern ecosystems.
Goats can be worse, if not very carefully managed. In part because goats are used in even more marginal zones, and damaged branches and grasses take much longer to regrow.
Freshwater fish are prone to parasites which can be transferred to humans. Saltwater fish can be eaten raw. The Plains Indians were well advised to avoid fish, at least until the introduction of the cast iron skillet, breading, and ketchup.