It’s an old joke — if you can’t describe a flavor, say it “tastes like chicken.” But chicken wasn’t always synonymous with generic. Chicken used to be flavorful, expensive. As author Mark Schatzker describes in his new book, “The Dorito Effect,” that all changed starting in 1948, with a contest to make chickens more plentiful — and less delicious.

To those who doubt the blandness of modern chicken, consider the following story:

In the town of McPherson, Kansas, there is a butcher shop called Krehbiels Meats, where, not long ago, an elderly woman bought a chicken that moved her to tears. The chicken had longer legs, a smaller breast and yellower skin than regular chickens, and on the back appeared two words the woman, who was in her 70s, would not have seen in a very long time: “barred rock.”

This chicken was a throwback, a variety nearly vanished since the 1950s and still raised the old-fashioned way, outdoors, where it ate blades of grass, leaves, seeds, bugs and whatever else it could put its beak on. The woman purchased one and took it back home, an hour south to Wichita.

She had every reason not to be excited. During the course of her 48 years of marriage, chicken had only ever brought disappointment. The problem was chicken and dumplings. It was one of her husband’s favorite dishes, but every time she made it, his verdict was always the same: “Not as good as my mother’s.”

The woman tried different recipes. She tried different ingredients. But as the years turned into decades, his judgment never wavered. After close to a half-century of marriage, she was married to a man who still missed his mother’s chicken. And that, it seemed, is how it was fated to be.

For whatever reason, the woman decided to give chicken and dumplings one more try with the barred-rock chicken from Krehbiels. This time, her husband was astounded. This time, he swallowed his dumplings and delivered the news she’d been waiting almost 50 years to hear: “This is my mother’s chicken and dumplings.”

It was at this point in the story that the woman began weeping. She was on the phone with the farmer who raised the chicken, an heirloom-poultry buff named Frank Reese, of Good Shepherd Poultry Ranch, whom she’d never met or spoken to before. As the tears flowed, she said, “I just wanted to call and thank you so much.”

Nothing tastes like it used to

The woman’s mistake, it turned out, had nothing to do with the recipes she’d been using. It had nothing to do with her cookware, her oven, the thickness of her dumplings, her gravy, the amount of salt and spices she used, the hardness of her tap water or any of the usual variables a home cook might place under the beam of doubt.

All that time, the problem was the flavor of the chicken itself.

It’s a complaint we hear often from the blue-hair set. Nothing tastes the way it used to. We tend to dismiss it as the rose-tinted memory of times past or the result of failing taste buds. But they are on to something. Food has changed.

Chicken’s descent into blandness began in March 1948, in Easton, Maryland, at a grand event that would determine the way soups, broths and braises of chicken would taste for decades to come.

The Chicken of Tomorrow contest was conceived by Howard “Doc” Pierce, who was national poultry research director with A&P Food Stores, one of the largest grocery chains of the time.

For anyone in the chicken business, the late 1940s was the best of times, but also the worst of times. World War II, which had just ended, had been good to chicken farmers. As red meat was rationed, Americans almost doubled the amount of chicken they ate. But with the war over, Pierce worried that the spike in chicken consumption would come to a crashing end. Pierce wanted to stop that from happening.

Chicken of the 1940s was nothing like it is today. It was expensive by modern standards, and since chickens were often the by-product of the egg industry, they came in a range of sizes. There were broiler chickens, which were young and tiny — some weighed in at just a pound and a half — and so tender you could cook them under a scorching-hot broiler. Next came fryers, which were a bit bigger and less tender, but still small. After fryers came roasters, and last came “fowl” — old hens that were so tough, they could be used only in soups and stews.

If a quick and easy Tuesday night dinner was what you had in mind, you needed a broiler or a fryer. You might even need two. And it was going to cost you.

What this country really needs, Pierce thought, is a steady supply of tender, large-breasted chickens. So A&P put up $10,000 in prize money and sent wax models of perfect-looking chickens around the country. Whoever could raise the flock of chickens that grew the fastest and looked most like the wax model stood to make quite a bit of money.

In 1946 and 1947, regional Chicken of Tomorrow contests were held. The cream of that group was invited to compete in the national event in 1948, which is how 31,680 eggs from 25 different states found their way to a hatchery in Maryland. Once hatched, the chicks were raised in identical pens and fed a secret diet that contained a minimum of 20 percent protein, 3.5 percent fat and 7 percent fiber.

After 12 weeks and two days, the chickens crossed the metaphorical finish line — they were slaughtered.

The chicken of tomorrow

Under bright and unflattering light, their plucked bodies were scored for things like uniformity of size; quality of skin; the length, depth and width of the breast; and performance traits such as hatchability, feed efficiency and average weight.

The winners were from Vantress Hatchery in California.

They were big, averaging 3.75 pounds, and scored 3.17 for feed efficiency, which means it took just over 3 pounds of feed for every pound of chicken.

This is what agricultural types call “improvement.” And it had been going on at a slowish pace for a couple of decades already. Back in 1923, it took 16 weeks to get a chicken to a relatively puny live “broiler” weight of 2.2 pounds, with a feed efficiency of 4.7. By 1933, that same broiler had gained half a pound and took two fewer weeks to do so.

By 1943, broilers were averaging 3 pounds at 12 weeks. These Vantress chickens, however, were something to behold. Not only were they roughly a full pound heavier than their peers, they somehow managed to get that big on less food. These were miracle chickens.

How did these miracle chickens taste? No one knows. The judges didn’t measure flavor. The point of the contest, after all, was to create a chicken that looked like a wax model.

The very principle demonstrated at the Chicken of Tomorrow contest would go on to doom the flavor of chicken and dumplings for decades to come: Chickens can be changed through breeding.

Growth rate and plumpness weren’t fixed physical laws, like the speed of light or the electrical charge of a proton. By choosing which rooster got to mate with which hens, you could change chickens’ genes. You could make chicks that were different — much different — from their parents.

Those genes kept changing. By 1951, the Chicken of Tomorrow winners got fat two weeks earlier than they did in 1948, and by 1955, the winning chickens of 1951 were just average. By 1973, it was down to 8½ weeks.

Everything, in other words, went according to plan. As World War II concluded, chicken consumption did indeed decline, just as Doc Pierce had feared. But then chickens got cheaper and plumper, and the eating of said chicken rebounded, rising back up to wartime levels in the early ’50s and then exceeding them by the middle of that decade.

By 1967, Americans were eating twice as much chicken as they had in 1948, and by 2006, chicken had become so cheap and so abundant that Americans were eating nearly five times as much as they had in 1948.

The dream of Doc Pierce, in other words, has been gloriously realized. Chicken is number one. The country that formerly preferred beef now eats 26 billion pounds of chicken every year.

Chicken is cheap. The bird that was selling for 60 cents a pound in 1948 was down to 39 cents in 1968. In 1948, a 5-pound chicken cost $3 — which might sound inexpensive, but in today’s dollars it works out to $30 for a single bird. In 2015, a supermarket chicken will run you $7. Chicken today costs less than a quarter of what it did during the Chicken of Tomorrow contest.

They are all broilers now. Words like “fryer” and “roaster” still appear in cookbooks, but they don’t exist anymore. We eat gigantic babies. As a paper in the journal Poultry Science puts it, if humans grew as fast as broilers, “a 6.6 lbs. newborn baby would weigh 660 lbs. after 2 months.”

What chickens eat

We paid in flavor for this “improvement.” In 1961, Julia Child and her co-authors of “Mastering the Art of French Cooking” stated that chicken “should be so good in itself that it is an absolute delight to eat as a perfectly plain, buttery roast, sauté or grill.”

Thirty-seven years later, Mark Bittman’s “How to Cook Everything” described chicken as “downright bland” and “essentially a blank slate.”

For the first 99.9925 percent of their domesticated careers, chickens ate all sorts of stuff: blades of grass, leaves, seeds, bugs, mice, frogs, meat scraps, dead rabbits, even snakes. Without green treats and outdoor foraging, chickens got sick and died. No one knew why.

Around the turn of the last century, a Dutch physician named Christiaan Eijkman observed that when his chickens were fed white rice and only white rice, they became afflicted with beriberi — they had difficulty walking, they would vomit, and eventually they became paralyzed and died.

If the sick chickens were fed brown rice, however, they recovered. Eijkman postulated that there must be something about brown rice, some hidden essence crucial to maintaining health, that was not to be found in white rice.

A few years later, a Polish biochemist by the superb name of Casimir Funk took the stuff that makes brown rice brown — rice bran — and treated it with alcohol and phosphotungstic acid and was left with a tiny amount of an almost magical substance that could cure a pigeon just hours away from death by beriberi. Funk called this revolutionary substance a “vitamine.” (It was, in fact, vitamin B1, properly known today as thiamin, and which, over the past 50 years, has been depleted by half in vegetables such as cauliflower and collards.)

The study of nutrition would never be the same. Thanks to vitamins, deadly diseases like rickets, scurvy, beriberi and pellagra would become not only treatable but preventable. Eijkman was awarded a Nobel Prize. (Funk got bupkis.)

But what Christiaan Eijkman almost surely did not realize is that thanks to him, the birds he was studying would, before the century was over, taste like teddy-bear stuffing.

As poultry scientists ticked off the list of vitamins, minerals, amino acids and the other microscopic substances essential to chicken life, feed makers began adding them to chicken feed.

Chickens didn’t need to go outside anymore. They didn’t need to eat cabbage and table scraps or a dead toad to get a “complete” diet.

In the late 1940s, a new and important feed was unleashed upon poultrydom: the “high-energy diet.” For chickens to grow twice as fast as their recent ancestors, they needed to mainline carbs.

There was, however, a tradeoff that no one thought much about. What the high-energy diet gains in calories, it loses in flavor. The feed is typically a blend of seeds — corn, wheat, millet, soybeans, etc. — and while some seeds (nutmeg, for example) are flavorful, the seeds we feed chickens are not.

The taste of animal flesh is strongly influenced by what an animal eats. Flavor compounds in the food birds eat find their way into bird tissue. Scientists refer to this as biodistribution — it’s the same reason a dairy cow that eats onion grass produces milk that tastes like onions. And the food we feed chickens today has no flavor at all.

Preflavoring lies

Why do consumers put up with chicken that tastes like … nothing? You can thank what the food industry refers to as “flavor solutions.”

When you stop to consider that nearly half of all chicken sold is “further processed” — chicken nuggets, chicken sausage, chicken patties, chicken burgers, chicken strips, chicken cutlets, chicken Kiev — that adds up to a lot of “preflavoring.”

If this makes you imagine, as I did, a man wearing a chef’s hat sampling a nugget and then sprinting to the other end of the factory while shouting, “More oregano! More oregano!,” think again.

Seasoning arrives by the truckload to chicken factories and is stored in big paper sacks in a kind of flavor warehouse alongside sacks of powdered marinade, breading and batter. Just tear open a bag and dump it in.

Because however complicated it may be to breed and grow chickens, that’s actually the easy part. Making a modern chicken taste good requires a flavor solution that calls for three rounds of seasoning that includes recognizable substances like garlic and oregano, unrecognizable substances like MSG or hydrolyzed yeast, and unknowable, secret substances called “natural flavors” or “artificial flavors.”

Making flavor solutions requires a cluster of scientific know-how that brings together advanced organic, analytic and synthetic chemistry with engineering, neuroscience, psychography, psychophysics, ethnography, demography, molecular biology, finance, botany, economics and physiology — even feelings.

If you are wondering why you’ve never noticed this thing called the dilution effect, why all that supposedly bland food we now grow tastes delicious — why people still want it despite its nutritional and flavor diminishment — it is thanks to flavor solutions.

So much of the food we now eat is not only a lie, it is a very good lie. Modern food may be the most compelling lie humans have ever told.

Excerpted from “The Dorito Effect: The Surprising New Truth About Food and Flavor” by Mark Schatzker, out now, published by Simon & Schuster.