The Evolution of Taste Sensation

The tongue map, once taught as the basis of taste perception, is a myth, as taste sensitivity is more evenly distributed across the tongue. The discovery of umami expanded the traditional four primary tastes to five, with each serving an evolutionary role in identifying food safety and nutrition. Additionally, individuals exhibit varying sensitivities to taste, with "supertasters" possessing more taste receptors and heightened sensitivity.

 

 

The Myth of the Tongue Map

For decades, students were taught that the tongue was divided into sections that each detected a specific taste: sweet, salty, sour, and bitter. This "tongue map" was first proposed by German scientist D. P. Hanig in 1901. However, more recent research has revealed that this map is a myth. It was later discovered that the sensitivity to tastes is more evenly distributed across the tongue, with small variations in receptor sensitivity across different regions.

 

The Discovery of Umami

While we once believed there were only four primary tastes, it is now known that there are five. The fifth taste, umami, was discovered in 1907 by Japanese chemistry professor Kikunae Ikeda. Umami, often found in foods containing monosodium glutamate (MSG), is described as a "good taste" or "good flavor."

 

The Role of Taste in Human Survival

The primary tastes served an evolutionary purpose for early humans, helping them identify the nutritional value and safety of food. Sweet foods provided a source of calories, salty foods offered essential nutrients, sour flavors signaled spoiled food, and bitter tastes often indicated toxicity.

 

How Taste Works

Taste sensations are detected by specialized receptor cells in the taste buds, located in the papillae (the bumps on the tongue). Each receptor cell has a gustatory hair that extends to the surface of the tongue. When a tastant (a substance that can be tasted) enters the taste pore and interacts with the gustatory hair, it sends a signal to the brain's gustatory areas, allowing us to perceive taste.

 

Sensitivity to Taste

Some individuals are more sensitive to taste than others. Studies using propylthiouracil (a compound used in thyroid disorder testing) found that 50% of participants could detect a bitter taste, while 25% could not taste it at all, and 25% experienced it as intensely bitter. These individuals, known as "supertasters," have a greater number of taste receptor cells and are more common among females and people from Asia, Africa, and South America.

Some individuals find the taste of cruciferous vegetables (such as Brussels sprouts and broccoli) to be extremely bitter—a taste that has been attributed to the same chemical found in propylthiouracil.