Thursday, February 4, 2021, 19:17
We certainly asked ourselves if we are able to leave the tongue to give him a tube. Some will have achieved it without greater difficulty, as if we have prepared a number of muscles to make from birth to make that movement in such a useless principle, while others have fought with a stubborn flat tongue without success. It is also very likely that they explained us below, perhaps in a class of natural or biological science form to the tongue. And the truth is that we have brought a few mistakes there: The language, just like other curious characteristics that enable us to classify people in two groups, is not as easy as some people believe stubbornly.
We will judge some of those peculiarities by the hand of the American professor John H. McDonald and his ‘myths of human genetics’. Be careful, because this is one of those reports that at certain times, They almost force the reader to make an unexpected gesture: the surrounding people may wonder what that is coming To suddenly get your tongue and rarely wiggle it.
The rule of the language
There are more people who can excite the language than people who cannot do this: according to different studies, Between 65 and 81% of society have no problem giving the language that appears of a Rulo, With the peculiarity that the percentage is slightly larger in women than in men. It has a genetic component, because the chance of being able to do this is greater if our parents can, but far from working with a mechanism as simple as the unique gene: in fact, in a study of 33 pairs of identical twins, there were seven in which a brother could let the tongue and the other not. Moreover, In research with children it has been proven that some learn to make this gesture, so that it is not even a sharp anatomical difference And it not only depends on genetics, but sometimes also on the effort made in childhood. Ah, there are some people (about 15%) who can curl the tongue in the form of a clover, fold it in three and even four lobes.
Forearms and fingers
The vast majority of people We cross the arms in a certain way and always place the same forearm above. If we deliberately try to do it differently, we will feel a strange discomfort. It is slightly more common than the dominant forearm on the left and is sometimes still heard as an example of a simple legacy, but the first study on this, almost a century ago, concluded that this issue had little or no genetic basis. The same happens with The thumb that we put on, Although there is a minimum of the population (about 1%) that has no preference.
Asparagus urine
Some have been enough to read this epigraaf to know what we are talking about, but others may have to explain: in short, many people notice a strong and unmistakable scent in their urine. This reaction presents certain complexities and has resulted in numerous scientific studies, because it seems that it We are actually talking about two different things: on the one hand there are people who excrete that scent and people who don’t (And that can be a Mendelian inheritance function, so that two non -excretorial parents could not get an excretion child), But there are also people who perceive it and people who don’t, nor in their own urine or in others. This has exceptionally complicated the research procedures: “Ask people if their own urine smells rare after eating asparagus is not a good way to tackle it,” McDonald summarizes. Another highly commented phenomenon is The ‘beet urine’, for the reddish shade he acquires from some people after he has set this tuber, But scientists have proven that there are not two clearly differentiated groups, but a red scale that covers the imperceptible to alarms (at least if you ignore the cause).
73%
Of the participants in one of the most recent studies, which were carried out in Nigeria two years ago, they were able to excite the language.
25.6%
Of the participants in another recent study, which took place in China, cut by suddenly exposed to light. The share was greater in men (30%) than in women (21%).
52%
Of the participants in a Spanish project of 1961, they placed their hands on the right when they cross their hands.
Car -dopistic thumb
If we ask the people of our environment to expand their thumbs and move them away from the rest of the hand, we will probably find a case of ‘car -dopist thumb’, in which in which Falanges form a highly marked corner and the finger bends back. In the introduction to genetics, many functions are also often resorted With a very spectrum of possibilities between straight thumb as a candle and the most extreme car -thumbist thumb. Of course the ability to bend your finger in this way is genetically influenced.
Light
If we are doing well, we can call it Sneeze. If we want to continue, we will refer to the dominant autosomal syndrome of Helio-Doftálmica Compulsive irruptie, a technical name whose playful acronym is pronounced in English ‘Achú’. The point is that One in four people sometimes sneezes uncontrollable by exposing yourself to a sudden bright light. In the beginning it is a harmless phenomenon, but it can lead to unwanted implications in the case of drivers, pilots and operators who treat heavy machines in mines and tunnels. Apparently it has a clear genetic component, but it does not depend on a single gene.
The two earwafes
There are two types of ear wax: one of them, the ‘wet’, is sticky and color between yellowish and brown; The other, the ‘dry’, has a good appearance, such as grain flakes, and a tone that takes care of gray. Second It is the most common in the East East (practically the only one in North China and in Korea), but it is much less common in Europe and is practically not found in Africa. Here we are confronted with a function that is transmitted by the most basic mechanism of inheritance: the allele of the dry variant is the recessive, so that two parents with that kind of cerum would be transferred to their child with violence. Professor McDonald, very tired of using the other examples in the classroom, claims that the ear washing would be “especially attractive” to treat it in the classroom: «The gene has been identified, the biochemical basis of the variation is understood fairly well, there are indications for natural selection and links with some issues related to health. But there are also a few problems to use it in class exercises. On the one hand, The dried wax allele has a frequency in the Western European population of 10 or 20% and is practically absent with the African population, so it is likely that everyone in a class with students of that origin has wet Aeman. The second problem is that many students mess in their ears in search of wax and then show that there can be a little unpleasant ».
“A geneticist always wonders why these qualities are there”
You can attract the attention that scientists spend time and effort to measure the corner with which hundreds of people fold their thumb or make many people smell urine monsters in search of the trail of asparagus. “In general, all characteristics, both physical and behavior, are interesting for a biologist, and more if you are a geneticist, because you always wonder why they are there,” says the molecular biologist, geneticist and scientific disseminator Julio Rodríguez. We always see everything from the perspective of evolution: as a function that will always have a bit genetic, here is with us, that is ‘something’ in the evolutionary process. The most normal thing is that it has been the natural selection that ‘filters’ those genetic variants that maximize the survival and reproduction of the individual. It seems clear that there are many functions that have nothing to do with survival, so the only thing they demonstrate, if they have a genetic component, is random genetic variability, but you don’t know that until it investigates ».
For example, the fact that the two types of wax have a diametrically opposite frequency in Asia and Africa leads to many questions: «Why is it? What happened in the evolution of these populations, so that is set in an allele and in others? It is interesting to rebuild the evolutionary history of a certain trait ».
