The preference or dislike for certain aromas is far from a whim, but is encoded in genetic material. A group of Icelandic scientists discovered that people with genetic mutations found that the smell of rotting fish was unpleasant and stronger than other fish.
Every year on December 23, Iceland will repeat the same mistakes. In memory of Thorlaco Torhallsson (ÞorlákurÞórhallsson In Iceland) or the island’s patron saint, San Thorlaco, is called ” Þorláksmessa.By then, restaurants, streets, and businesses in Reykjavik, Kopavogur, Hafnarfjord and other cities have suffered Strong smell of rotten fish.You cannot escape the oily smoke in the fermentation bar or Castel SkardaThis is a typical Icelandic dish, decorated with boiled potatoes and radishes, melted lamb fat and sweet rye bread, to start Christmas.
This has been the case for centuries. The rays will not rot, but will undergo fermentation and curing for several months.As Sour herring Swedish-fermented herring from the Baltic Sea-and Lakfisk The Norwegian-smelly trout that has been eaten since 1348-this Icelandic food has its downsides.This Polls It shows that the number of lovers of this unpleasant centuries-old food is declining. Almost two-thirds of Icelanders are tired of its unpleasant smell.
There are many reasons: generations have changed, customs have changed, and new attitudes have been adopted.Or, to put it simply, it might be Genetic cause Some people find that the taste of fish is usually stronger and more unpleasant than others.That’s the warning Rosa GisladottirHe is a researcher at deCode Genetics and a professor at the University of Iceland. He has conducted the largest research on human olfactory genes and discovered the material basis behind the diversity of “nose taste”.
The research team led by Gísladóttir scanned the genomes of 11,000 Icelanders for a mutation that affects the sense of smell and discovered a mutation in a specific gene called TAAR5 that affects the sense of smell. Three et, The compound responsible for the smell of rotting fish.
“We have discovered variants in the sequence that affect the way we perceive and describe the fishy smell,” the scientist told SINC that his research was published today in the journal Current biology. “Our sense of smell is very important for the perception of taste. This is why these variants may affect whether we like foods that contain these smells.”
Smell affects our food preferences, mood, and even partner choices. Even so, although the Nobel Prize winners Linda Buck and Richard Axel in 2004 in the early 1990s have made great progress since their discovery of odor receptors, it is still one of the most mysterious and little-known sensations.
One of the most interesting aspects of scientists is “nasal relativity”, that is, how the sense of smell varies from person to person. No two people smell the world in the same way. There are about 4 million olfactory cells in the human nose, divided into about 400 different types of olfactory receptors, each with different variants.
in a article British biochemist John Amoore (John Amoore) published an article in 1976, pointing out that 7% of people are particularly averse to the smell of rotting fish, that is, they cannot perceive it.
In its natural state, fish tissue contains an odorless substance called trimethylamine oxide, which is essential for organisms living in saline-alkali environments. Once these animals die and their bodies are exposed to the air, enzymes and bacteria break down these molecules into another substance: trimethylamine, causing them to emit an unpleasant smell. As time increases, its concentration increases.
In order to understand why the smell of fish is unpleasant for some people but not others, researcher Rósa Gísladóttir scanned the genomes of 11,000 Icelanders to look for variants that affect the sense of smell, and asked volunteers to smell a series of aromas, they would identify and According to their intensity and pleasure. / Jón Gústafsson-Amgen Inc. of DeCODE Genetics
Interestingly, the smell of fish is tolerable for many people, but not for others.To find out why this happened, Gísladóttir used the so-called “Icelandic experiment”: it was founded in 1996 by the biopharmaceutical company molecular biologist Kári Stefánsson (Kári Stefánsson). Decoding Genetics it has Genealogical data of all Icelanders, Blood samples of 160,000 individuals, and the complete genomes of approximately 60,000 volunteers aged 18 to 96. These volunteers have given informed consent to 120 employees of the company and can use their data to understand the root cause and diversity of the disease And evolution. Over the years, more than two-thirds of the Icelandic population has participated in some genetic research on deCODE.
The team led by Gísladóttir first recruited 9,122 Icelanders and studied the genetic variations that affect odor perception. The researchers asked the study participants to smell a series of smells presented to them on a pen-like device: Fish, lemon, licorice, cinnamon, mint and banana.
Then, volunteers must identify them and rate them based on their strength and satisfaction. This exploration led to the identification of three gene variants, which the scientists confirmed in a control sample of another 2,204 Icelanders.There is a person Specific mutations in the TAAR5 gene They are more likely to say that when the fishy smell is introduced to them or not seen as offensive, they smell nothing. They also use words to describe words that are not related to trimethylamine, such as “caramel” or “pink.”
Gisladottir said: “Carriers of this variant find that the fishy smell is not so strong and unpleasant, and it is unlikely to name it accurately.” So far, research on the gene has been focused on animals: with 1200 Mice with an olfactory receptor associate the odor of predator urine with dangerous odors and instinctive escape odors. Now, the team’s findings extend the significance of this research to human perception and smell.
He said: “One of our main findings about Icelanders’ sense of smell is related to the smell of fish, which is kind of ridiculous.” Traditionally, Icelanders consume a lot of fish. Iceland is a convenient place to conduct this research because trimethylamine is a common odor in our diet. “
Weaknesses of Licorice
This is not the only surprise the team got. Icelandic scientists have also identified genetic variations related to the smell of cinnamon and licorice: mutations in the OR6C70 gene may contribute to a preference for black licorice.
“We found the impact Feel the smell of licorice and cinnamon They differ in frequency between groups of people.The scientist said: “Especially the licorice variety, which is more common among Asians than Europeans.” “This is interesting because one of the components of the smell of licorice is TransaminolIt is found in a variety of spices and plants, which are widely used in Asian cuisine and traditional medicine, such as star anise.
Research by Gísladóttir and his team at deCODE Genetics shows that mutations in olfactory genes affect human perception of smell. They admit, but reducing the odor preference for organisms is very simple: in addition to having genetic roots, the neglect of fishy odor is partly regulated by farming. People who do not eat fish smell more unpleasant than those who eat this food. In addition, because rotten fish is often associated with food poisoning, we have the conditions to find its odor annoying, not appetizing.
Therefore, English since the beginning of the 19th century expression”fishy” Describe the suspicious behavior or situation. As the psychologist Norbert Schwarz (Norbert Schwarz) pointed out, referring to something or someone with suspicious or turbid characteristics is different from one country to another. , Although they always use food or organic matter in a bad state as a source: for example potatoes or rotten meat.
Among members Tribute to Da Azanah In southwestern Ethiopia, odors associated with goats and cattle, such as dung, are thought to have aromas. Because cattle are the core of this society, it smells like wealth and higher social status. On the contrary, daasanach hates the smell of fish, because fishermen are considered to be the lowest members of society, so their smell is classified as unpleasant.
As evidenced by Icelandic scientists, the answers to these olfactory mysteries exist not only inside, but also inside.
Current biology, Gisladottir et al.: “Sequence variation in TAAR5 and other loci can affect human odor perception and naming” https://www.cell.com/current-biology/fulltext/S0960-9822(20)31343-9