"What we think of as our culture's foods — ketchup, or fish and chips — usually developed over long periods of time across many cultures," says Dan Jurafsky.

Jurafsky is a Stanford linguist and author of the fascinating new book, "The Language of Food." In it, Jurafsky digs deep into the history of the words we used to describe our food — and uses it to show the winding, often surprising background of many dishes that feel utterly familiar to us. When I reached him in September to talk about it, he began by telling me about fish and chips — "the most surprising" of the stories he unearthed.

You probably think you know where fish and chips comes from. Britain. It's pretty much the national dish. Fried fish. Fried potatoes. Vinegar sauce. Pip pip, cheerio, and all that.

You're wrong.

The 6th century origins of fish and chips

But the dish didn't begin in Britain. "It began as a sweet-and-sour meat stew in 6th century Persia," explains Jurafsky. It was flavored with vinegar, and was a favorite of the Shah. After the Shah was overthrown, it was adopted by the court of Baghdad. Fried fish was added, and onions, and vinegar. It became known in the Christian part of Europe. In those days, Christians had a lot more fast days — which meant they couldn't eat meat or dairy, but they could eat fish — than they do now. So the stew became popular in Christian cookbooks.

In Spain, the stew was called escabeche. But then the Jews were kicked out of Spain, and they brought their fried fish and onions and vinegar to England. In Oliver Twist, Charles Dickens talks about the "fried fish warehouses." Then potatoes came to England and fish and chips were born.

But it doesn't end there. Portuguese Jesuits went to Japan and brought their fried fish with them. It became tempura. The dish went to Peru, and it became ceviche. These symbols of national cuisine are actually riffs on foods beloved by other countries.

Ketchup, from the Chinese word for fish sauce

"The word ketchup came from Chinese," Jurafksy says. It's a mixture of the word "tchup," which means "sauce" in certain Chinese dialects, and "ke," which refers to preserved fish. And there's a reason for that. Ketchup began as fish sauce.

"Go back thousands of years ago," Jurafsky says. "How do you preserve food? You use salt. In Southeast Asia, people stacked fish with salt in jars. One method was you would layer fish and rice and it would ferment and get goopy, and then you'd wait a few years, scrape off the rice, and the fish would be preserved. Eventually people began doing it with fresh fish and vinegar. That's the ancestor of sushi.

"But people kept preserving fish and making these fish sauces. Eventually you have Chinese sailors colonizing the rest of Asia, and bringing fish sauce and soy sauce and distilling liquor. The British and the Dutch and the Portuguese sail to Southeast Asia looking to trade. But beer and wine go bad on those trips. So distillation really takes off. They begin buying thousands of barrels of liquor from the Chinese, and they buy a few barrels of preserved fish sauce on the side. Back home, it becomes this sauce. But it's expensive. So people begin creating knockoffs. They do it out of mushrooms, out of walnuts, and then tomatoes arrive from the New World. Eventually, the fish die out of the sauce. So this is really the beginning of ketchup as we know it."

Meditate on that for a second: ketchup is the cousin of sushi.

Why we toast

Jurafsky's book is full of these sorts of stories. Ever wonder why we "toast" people?

"In the Middle Ages, you often drink wine or ale or broth with toast in it. It's called 'sops'. You put in hot bread and it heats up your wine, adds flavor, adds calories. Shakespeare talks about this a lot. Just as the custom was dying out, they started this tradition of drinking to your health at English dinner parties. And they began calling the person who was the spice of the evening 'the toast,' because toast spices wine. That's where 'toast of the town' comes from, and the verb 'to toast' develops out of that."

The point of Jurafsky's book is that "surrounding us everywhere in the words we use to describe food are hidden messages that we don't notice." It's as true today as it ever was. Take Yelp reviews.

The trauma of a bad meal

"People who give a one-star review of a restaurant display all the signs of a minor trauma," Jurafksy says.

"Social psychologists have looked at cases of trauma and the language people use after. They looked at blog posts after 9/11 and campus newspapers after tragedies. The clues they found were the use of past tense way beyond what's normal. You talk about other people a lot. You use very negative vocabulary. And you use the first-person plural — you use 'we' or 'us' more often than would be expected.

"You've suffered this traumatic event and you're taking solace in the fact that this bad thing happened to us and we can weather it together. That's exactly what you see in these one-star reviews."

If that seems a little extreme, well, that's the point. There's little that's more fundamental to the human experience than eating. It's not just how we generate the energy to live; it's how build our communities, welcome our friends, spend time with our families, define our nationalities, connect to our past, end our feuds, court our partners, and celebrate our triumphs. No wonder a bad meal throws us off.

But don't worry. We'll get through it. Together.

More on how we eat: 40 maps that explain food in America.