Scientists debunk the tongue map theory | Press

Article published in the journal Nature states that the entire tongue can identify the five tastes.

Contrary to what many imagine, the human tongue does not have specific regions that separately identify each of the five basic tastes—sweet, salty, sour, bitter, and umami. At least that is what a supplement recently carried by the British journal Nature, one of the world’s most renowned scientific publications, argues.

According to one of the articles published, the entire surface of the tongue is capable of identifying the five tastes, regardless of location. That is because the tongue has receptors present in the taste buds, which in turn are spread across the whole tongue.

The myth of the tongue map began in the early 20th century, when a German researcher named David Hänig published an article with information on taste sensitivity in different parts of the tongue. “The article ended up being misinterpreted, and the ‘tongue map’ was mistakenly created,” explains Hellen Maluly, professor of Food Bromatology and Toxicology at Faculdade Oswaldo Cruz.

The first clue showing that the tongue map was nothing more than a myth came in 1931, when the American chemist Arthur Fox accidentally released a cloud of the organic compound phenylthiocarbamide during an experiment. A nearby coworker reported that the substance had a bitter taste. Fox, on the other hand, could not detect the sensation described by his colleague. After some tests, the chemist realized that taste perception was closely linked to each person’s genetic characteristics, a fact later confirmed by geneticist Lawrance H. Snyder.

The discoveries of Fox and Snyder triggered a series of further studies. Research advanced, but only after 70 years did scientists identify the specific mechanisms for each of the five basic tastes: bitter (2002); sweet (2002); umami (mGluR in 2000 and TR1 and TR3 in 2002); sour (2006); and salty (2010)—see the full timeline in the infographic. “Each taste bud has receptors or ion channels that trigger different mechanisms for the five basic tastes. In addition, each individual may perceive tastes in their own way because it depends on their genetic traits. For this reason, there is no specific pattern for all humans, which debunks the old tongue map,” Hellen concludes.

UMAMI TASTE

Umami is the fifth basic taste of the human palate and was discovered in 1908 by Japanese chemist Kikunae Ikeda. However, it was only recognized by the scientific community in 2000, when researchers at the University of Miami found specific receptors on the taste buds. The amino acid glutamate and the nucleotides inosinate and guanylate are the main substances that provide umami. Parmesan cheese, tomato, mushrooms, and meats in general are foods that contain these substances in high proportion and therefore display the fifth taste more intensely. The two main characteristics of umami are increased salivation and a lingering taste for a few minutes after eating.