A taco vendor scans the beach for clients on in Acapulco, Mexico. (John Moore/GETTY IMAGES)

T here is a joke that the citizens here require a special nutritional supplement in order to thrive, and that would be Vitamin T, contained in tamales, tortas, tostadas, tlayudas, tortillas, tequila and — first among equals — their tacos.

Is there any food more sublime than tacos al pastor, the King Kong of Mexico City street fare, served up on plastic plates 24-7 at a thousand stands by a taquero who shaves off the caramelized pork from the twirling rotisserie, plops the shreds of meat into a warm tortilla lying open like a welcome mat in the palm of his hand, adds chopped onion and cilantro, and then finishes it off, with a flick of his knife, by adding that genius bit of pineapple?

How timeless, how authentic, how . . . 1950s?

As the binational foodie wars wage — who invented what and when, and why have the gringos annexed it (again)? — the curious eater is now blessed with not one but two new books about the rise of the taco as the international rock star of consumables.

Here we learn that the Crunchy Taco Supreme from a Taco Bell in Arkansas and the tacos arabes on pita bread, served up at Taqueria el Greco in Mexico City, may be closer cousins than we think.

“The idea that the taco is somehow deeply authentic isn’t supported by the facts. The taco is kind of like chop suey and pepperoni pizza. Tacos are a product of modernity. And this is true not only in the United States but in Mexico,” said Jeffrey M. Pilcher, history professor and author of “Planet Taco: A Global History of Mexican Food.”

Gustavo Arellano, syndicated columnist behind “¡Ask a Mexican!,” eats off the same plate in his new book, “Taco USA: How Mexican Food Conquered America,” in which he embraces the wandering taco as a shape-shifter, a mongrel not sapped but strengthened by its appropriation north of the border.

“The taco is the longest-lasting soul survivor, endlessly customized,” said Arellano, who also rhapsodizes on Major League Baseball cheese nachos and a bacon-wrapped, bean-stuffed frank called the Sonoran hot dog.

“The idea that all authentic Mexican foods date to the Aztecs and everything else is McDonald’s isn’t true,” said Pilcher, who argues that Mexican food in Mexico is an amalgamation of cultures, foreign and domestic, as regional ingredients and cooking styles continue to bend and blend.

Arellano chides food nazis, Chicano leftists and celebrity chefs such as Rick Bayless who see Mexican food with a tunnel vision that separates everything into “authentic” (pure, true, indigenous Mexican cuisine) and “Americanized” (neocolonial, globalized glop).

“It’s nonsense,” Arellano said. “It’s not supported by historical record.”

Both authors stress that there are really just two kinds of tacos: good ones and bad ones.

“Of course, the idea of the taco is very old. You take a corn tortilla, stick something on it, roll it up and eat it,” said Pilcher. “But they didn’t call it a taco.”

Drawings of women rolling corn masa into tortillas can be found in the Florentine Codex, an account of life in Mesoamerica compiled by Spanish friars of the 16th century. It also contains images of Aztecs maybe eating maybe tacos.

The word “taco” appears in Spanish dictionaries dating to the 17th century, but not meaning foodstuff. To blast ore, Mexican miners would wrap an explosive charge in a wad of paper called a taco. “So with circumstantial evidence, you could see someone calling a tortilla wrapped around beans and chilies a taco — a culinary explosion,” Pilcher said. He found later references to tacos de minero.

The first printed recipe for a taco that Pilcher found comes from a 1904 edition of the Mexico City newspaper Diario del Hogar. It was no taco we would recognize today: It was a crepe made with pastry and rose water.

In the United States, Arellano discovered an 1899 Los Angeles Times article by the travel writer Olive Percival. The taco she encountered in Mexico was “a turnover filled with chopped, highly seasoned meats.” She didn’t dare try one.

Pilcher finds mention of the first “taco shops” in Mexico City tax records for poor neighborhoods of the 19th century, when migrants were pouring into the industrial capital. Later, tacos moved to middle-class colonias, as the nouveaux riches embraced a new national cuisine.

The food writer and culinary guide Lesley Tellez leads “taco tours” through the La Condesa neighborhood of Mexico City, one of the original taco zones. On a recent Saturday afternoon, tagging along were a taco-obsessed couple from Australia and a publicist for an international festival celebrating regional delicacies.

One taco led to the next: an aromatic Swiss chard filling at Tacos Hola, followed by a sweet stuffed chile relleno taco at Tixtla, then a blue corn tortilla stuffed with barbecued lamb steamed in maguey leaves at El Hidalguense.

Tellez relates the story of how, in the 1930s, Lebanese immigrants to the Mexican state of Puebla turned the Middle Eastern kebab into tacos arabes — lamb, later pork, tacos wrapped in pita bread.

Their rotisserie spit was a hit. Then, in the 1950s, it was employed to create the Mexico City classic: tacos al pastor, the same thing but with spicier pork swaddled — instead — in a corn tortilla.

Just a few years later, in 1962, Glen Bell opened his first Taco Bell in California. Today the chain has more than 6,000 restaurants around the world. One of the few places it has not succeeded — despite two tries — is Mexico.