What is body odor?

Let's start with a little-known fact: in fact, it is "normal" to have body odor, and it is "abnormal" to have no body odor.

abstract:

1, what is the cause of body odor?

2. What kind of people have body odor?

3. How to eliminate body odor? What is the mechanism?

4. What are the characteristics of people with body odor?

(a) indicate the author Zhihu.

@ Lee Shawn

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1, the cause of body odor

There are two kinds of sweat glands in human body: 90% are eccrine glands, which are distributed all over the body. Sweat is thin and generally tasteless. The other is apocrine gland (also called apocrine gland), which is mainly distributed in armpit, crotch, areola and external auditory canal. Sweat also contains a variety of protein and fatty acids, which are related to body odor. Sweat glands cry in the toilet: "What I secrete doesn't stink!" ") Well, that's true. Sweat secretions of apocrine glands are odorless, but they are decomposed by bacteria on the body surface to produce various unsaturated fatty acids, so they smell bad. The direct murderer is bacteria, but how can there be no bacteria on the surface of the human body? So, no matter how wronged you are, you can't escape, who let you provide the murder weapon!

2. What kind of people have body odor?

The mechanism of body odor is also mentioned in other answers above, but the answer here does not really answer the question. Think again, the problem is coming: everyone has sweat glands and everyone has bacteria. Why do only a few people have body odor?

In fact, there are not "a few" who have body odor! At the beginning, our ancestors all had body odor. In animals, body odor plays a great role as a pheromone in communication, so most animals have it. For people, body odor still plays a role in attracting the opposite sex. Male body odor can cure irregular menstruation. Of course, after people have a language, body odor communication is not so important, but they still retain the remains of their ancestors.

Before the 2000 generation, we had ... (the word 1994 is omitted here). After our great-grandparents left tropical Africa and entered temperate Asia, the 538th base of ABCC 1 1 gene in the middle of chromosome 16 was mutated, which led to the decrease of apocrine gland secretion. This mutant gene occurs in East Asia, because there is less sweating, which is more suitable for the cold climate in temperate zone and has genetic advantages. Therefore, after 40,000 years of natural selection, the mutant genes for removing body odor have become the majority in East Asia, but body odor has become a very small number. So people who don't have body odor are all descendants of that gene mutation, and they are all mutants. Do you feel like X-Men? 95% of China people are X-Men, and more than 99% of the population in North China and Central Plains are X-Men. China people have escaped the fate of living with body odor all day long. You have no idea how small the probability is.

People in other areas are not as lucky as people in China. In East Asia, Koreans are similar to China, and 99% of them have no body odor. But only 84% of Japanese people don't have body odor, 16% people have body odor! One in six people. Think about it. This is not the worst, not in East Asia, but worse! Only 30% of the aborigines in Oceania have no body odor, and only 10% of the whites have no body odor! Only 0.5% of black people don't have body odor! In other words, except for East Asians, almost all people with crooked nuts have body odor! Look at the gene distribution map of body odor below. The yellow one is the X-Men type without body odor, and the blue one is the wild type with body odor. Except the yellow land in East Asia, the rest of the world stinks! There are far more people with body odor in the world than those without body odor! This is why it is normal for people to have body odor. Do students with body odor feel that they have bad breath in their chests: you are all perverts! Why do students with body odor still feel inferior? The sentence "All men are brothers within the four seas" is really for you!

Figure: Global distribution of mutant genes for removing body odor (blue = body odor, yellow = no body odor).

(Image from:/gnxp/why-the-Japanese-think-western-SME-bad-well-one-reason/)

Some people might say it's body odor, not body odor. Sao nian, I am sad to tell you that body odor is body odor, and body odor is body odor. Including China's ancient poems, saying that women "sweat thin and cool, and cool shirts are thin and sweaty" is also a body odor. One is fragrant and the other is smelly, which seems to be opposite, but the mechanism is exactly the same. It smells good when it's weak, but it stinks when it's strong. Even the feces in the stool will turn into flowers after dilution and can be used as perfume. When you understand this truth, you will know that you can't wear too much perfume. If you spray too much, it will become a shit spray! You will also understand that only "thin and cool" people are sweaty women. Too many clothes cover is "body odor, thick clothes are hot, and hot clothes are thick and smelly."

The "no body odor" mentioned in this paper just follows the customary saying, and strictly speaking, it is just "the body odor becomes weak". It is not absolutely different from body odor, and no one is completely tasteless.

3. How to eliminate body odor? What is the mechanism?

Everyone smells like crooked nuts. Oh, my God! How did crooked nuts live to this day in the body odor?

It's not as hot as you think. Foreign countries do not stink everywhere. At least not in developed countries. Since body odor is so common, there must be a very popular and effective response. It's simple, that is, use deodorant. What's the Chinese name? Deodorant? Please use deodorant! That's toilet spray! Update: I was told in the comment area that it was called Fragrant Body Dew. )

Since the causes of body odor are 1 sweating and 2 bacteria, the mechanism of perfume lotion inhibiting body odor is from these two aspects. The common ingredients and functions of perfume body lotion are as follows:

1) aluminum salt as an antiperspirant. When aluminum salt meets acid sweat, it condenses into gel to block apocrine glands and prevent secretion. When you encounter alkaline soap in the bath, the gel will dissolve, dredge the sweat gland mouth, discharge secretions, and not block the prickly heat. So reapply antiperspirant lotion after each bath. It has been mentioned that alum (potassium aluminum sulfate) can be applied under the armpit to treat body odor, because alum is also an aluminum salt, which can stop sweating. The most common ingredient of antiperspirant emulsion abroad is zirconium aluminum tetrachloride glycicin. Oh, look at my long name. It's more than enough to block your sweat glands.

2) Alcohol: Its function is sterilization. It has been mentioned that antibacterial hand cream can get rid of body odor by applying it under the armpit, and the mechanism is the same, because the main component of antibacterial hand cream is alcohol. When there is no perfume, you can use antibacterial hand cream for emergency.

3) Ammonium aluminum sulfate: continuously inhibit the growth of bacteria. Sterilization at one time is not enough. After a long day, the bacteria will reproduce again in a few hours, and it still stinks. It's too much trouble to apply underarms repeatedly all day, so there must be a continuous bacteriostatic agent. This is made of ammonium aluminum sulfate, which can be used for one day at a time. It is also mentioned that urotropine solution can eliminate body odor and is also an antibacterial agent. The principle is that urotropine slowly releases formaldehyde and ammonia in acidic sweat environment to achieve the purpose of continuous sterilization. The disadvantage is that formaldehyde and ammonia have great side effects.

4) essence: the function is to cover up the smell. After the above three lines of defense, if there is still a little aftertaste, finally cover it up with essence. When the body odor is serious, you can't cover it up with essence alone, but it is more sour and refreshing when mixed. It is good to use it in combination with other means above.

Most body lotions on the market are effective against body odor because of the multi-pronged approach of the above ingredients. Different brands of body lotion may have different ingredients, some are pure antiperspirant, some may not have antiperspirant ingredients, and some may be pure essence. Pay attention to the label to distinguish it. Brands are not recommended here. Fragrant body lotion is not high-tech, but ordinary daily necessities such as shampoo and skin cream. Most brands have similar effects. Just try one.

The secretion of apocrine glands is also influenced by hormones in the body. People with body odor genes generally start to have body odor after puberty, and children before puberty can't see it. In addition, diet, mood and menstrual period will also affect the hormone level in the body, thus affecting the degree of body odor. But with a simple and effective body lotion, there is no need to mention those uncontrollable eating methods.

Shaving armpit hair can reduce the space of bacterial reproduction and reduce the degree of body odor, but the effect is very limited.

Finally, you can surgically remove the axillary apocrine glands.

Tell a true joke: an American friend of mine went to Shanghai on business, but she ran out of perfume and went to the supermarket to buy it, but she couldn't find it. Friends, what a surprise! That kind of feeling is probably like China people going abroad and finding that there are no chopsticks and slippers in the hotel! To Americans, a person who doesn't wear perfume is like a person who never brushes his teeth. That friend made an earth-shattering international call overnight to consult me. I told him: It's not that China people don't pay attention to hygiene, but that we X-Men are born with the ability to deodorize! International friends are shocked! It turns out that the streets and alleys of this country are full of X-men! Refresh the three views! That was many years ago, and now he is still telling people everywhere: When going to China for business, you must bring enough fragrance and body dew!

Fragrant body lotion is really common in America. Any daily chemical supermarket has at least a whole box of various brands of scented body lotion, including spray, paint, paste, powder cake and crystal. Although I haven't used it, at least I don't think the United States is covered with body odor, which shows that body lotion has a good effect on body odor. So students with body odor don't have to worry. There are so many choices. If you can't buy it in China, you can try to buy it (update: the comment area says that Watsons or supermarkets in China also have it, but there are not many varieties to choose from).

(Image from:/cotton+buds/funny-pictures/4909179)

How amazing is that a large number of scented body lotions and large bags of cotton swabs in foreign supermarkets, which seem to be out of reach, are caused by the same gene.

We China X-Men don't have to pick our ears every day, which is another advantage. Or more evolved than crooked nuts? Actually, it's not necessarily!

Clever you must have noticed the distribution of apocrine glands. There's something I haven't said yet. Hmm! Mammary gland is also a variant of apocrine gland! Hey hey, do you suddenly have a bad feeling? )

Ah! Is China Girls Airport also one of the superpowers of X-Men? This is not true. Breast size mainly depends on adipose tissue and has little to do with breast. There is no necessary relationship between breast size and lactation ability.

However, the mammary gland is directly related to lactation ability. The incidence of insufficient milk in Asian parturients is significantly higher than that in western parturients, which is also caused by gene mutation to remove body odor!

Therefore, the gene mutation to remove body odor is not necessarily an advantage, but it also has the disadvantage of insufficient milk. In the colder regions of East Asia, sweating has more advantages than disadvantages, so it has become the mainstream in East Asia. However, people with the same mutant gene went south to Southeast Asia, or crossed the Bering Strait into America, and then went south to Central America. In the tropics, less sweating becomes a disadvantage. Gene mutation itself does not matter evolution or degradation, but blind change. Whether it can be inherited depends on nature. Whether the inherited genes are more adaptive to the environment or less adaptive to the environment also changes with the change of time and place. Translating evolution into "evolution" is misleading, and now it has been changed to a more neutral "evolution".

In fact, what this article really wants to say is not evolution, but to tell all boys a truth: if you want your wife to be milk-like, you must marry a bitch! (serious face)

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Here, I will focus on answering your question:

Because the questions in the letter are all repeated questions that have been answered in the text, I emphasize here that private letters will not be answered! If you need to reprint, please read the authorization at the beginning of the article without writing to ask. )

I received many private letters from people who asked me the same question: "I wonder if my situation is bad." First of all, there is no absolute difference between "with body odor" and "without body odor", only the degree of light and heavy taste. Everyone put their noses under their armpits and smelled everything. As long as they don't smell it within the daily contact distance, it's not body odor. Secondly, if you don't know if you have body odor, then nine times out of ten you don't have body odor gene, and occasionally it's just a matter of living habits. People who really have body odor will obviously feel different from others and have no doubt at all. Finally, I wrote such a long article that the whole article means: it doesn't matter whether there is body odor or not! If others can't smell yourself, that's fine. If you suspect that your smell is too strong for others to smell, put on some perfume and the problem will be solved. Even if there is no body odor, there is no harm in wearing some body lotion, just like spraying perfume with soap. Why worry about stinking?

Is deodorant bad for your health? I've used crooked nuts since I was a child. I've never heard of them. Antiperspirants only stop the two tablets under your armpits, not the rest of your body from sweating. If you believe in Chinese medicine detoxification or something, forget it. But in the end, I still want to remind everyone that products with clear ingredients and clear mechanisms are more assured, and products with unknown ingredients and unclear mechanisms should be cautious. If the ingredients contain "red powder", be careful, long-term use will lead to chronic mercury poisoning. In addition, as long as you see someone who claims to "eradicate body odor", you can fan them with two ear scrapers. It is definitely a scam! Body odor is caused by genes, and the current medical level cannot be cured with drugs. Even surgery may not cure the disease.

Why do so many people say big breasts? I made it clear that big breasts have little to do with big breasts. You are all excited to see only the word "big breasts". Well, I can't see anything else.

The relationship between earwax and body odor is not 100%, but a high probability. According to statistics, 860 people with body odor have oily earwax. I don't know why some people have oily ears but no body odor, or have body odor but no oily ears. If anyone knows, please tell me. (Comment area @Laplata pointed out that gene dominance is also a high probability. Even if you carry genes, there is a small probability that you will not show traits. I think it makes sense. At the same time, it can also explain why some people have ear oil, one armpit stinks and the other doesn't. )

The "lack of milk" mentioned in the original text is only for popularity and is not accurate. In fact, it is precisely "colostrum deficiency." Colostrum is the milk secreted 2 ~ 3 days after delivery. The relationship between body odor and colostrum is not 100%. Please pay attention to the wording in the original text. Although the last sentence of the text is a joke. However, there is a correlation between body odor and colostrum, which is well-founded. If you are interested, please read this paper: the strong connection between human ear wax type and abortion comes from the colostrum secretariat of breast.

Simply and rudely answer the genetic question that everyone cares about: body odor is dominant inheritance, and no body odor is recessive inheritance. In other words, if parents don't have body odor, children won't have it. Occasionally there are exceptions, and the probability is very low, so I won't discuss them in detail. Among East Asians (the frequency of body odor gene is low, assuming that most people with body odor are heterozygotes), if one parent has body odor, then the probability that the child has body odor is 1/2. If you marry a foreigner (the frequency of body odor genes is high, assuming that most of them are homozygous), the probability of children having body odor is close to 100%. Only the most common cases are discussed here, and other cases with less probability will not be detailed here. Professionals should not spit. In addition, some people say that body odor is inherited from the X chromosome, which is wrong. The X and Y sex chromosomes are chromosome 23, and the body odor gene is on pair 16, so it has nothing to do with body odor.

However, why are you so obsessed with whether children will inherit body odor? Again, I have written for such a long time, and the whole article means: it doesn't matter whether there is body odor or not! If the child has body odor, just give him/her body lotion, and no one will notice.

Several people asked: If Asians adapt to the cold climate in Asia because they sweat less, so it is colder in Europe, then why don't Europeans have this gene? First of all, the mutation of deodorization gene appeared in Asia 40 thousand years ago. At that time, Asians had parted ways with Europeans, and the mutated Asians did not migrate to Europe, so the deodorization gene was not brought to Europe. So, why didn't Europeans independently develop a deodorizing gene? Mutation is not something you can change if you want, but you can change if you want. Mutation is like two dog's neighbor winning the first prize in the lottery. Just because you bought it doesn't mean you will win. Deodorization gene only won this time in tens of thousands of years, which is much more difficult than winning the first prize in the lottery! Mutation+cold climate = the mutant gene has genetic advantage, which does not mean that the cold climate will definitely mutate.

Others asked: I don't have body odor. Why do I still stink if I don't take a shower for a few days in summer? This MengMeng mutant, SAO Nian, God gave you super powers to use responsibly. Have you ever heard that the greater the ability, the greater the responsibility? If you abuse your superpowers like this and don't take a shower for a few days, God will punish you and become an ordinary person.

Will there be a recurrence of body odor after the operation? Are there any side effects? I'm not a clinician. I don't know. I only know that apocrine gland is not a single piece of tissue, but mixed with other skin tissues. It is difficult to remove apocrine glands alone without damaging other skin tissues. Whether it can completely eliminate/relapse/side effects depends on the technique used in the operation. Some technologies will leave big scars on belts and meat, while others will not be completely removed. I saw many close friends saying that they had had surgery in the comment area, and they thought it had both good and bad effects. Look at the comments section and ask them privately, and you will get a better answer. It's just that I personally think that with a simple and effective body lotion, why do you have to have an operation?

As for the relationship between body odor and breast cancer, there is no conclusion at present. Some surveys show that women with body odor have a higher risk of breast cancer than women without body odor, but some surveys also show that there is no significant difference between the two. Scientists are still tearing, please wait patiently for the result.

As for the relationship between body odor and armpit hair, the relationship between body odor and sweating, and the relationship between body odor and tintin size, classmates, your brain holes are too big! It's too big! It's too big! It doesn't matter. Say it three times. This is an echo.

If you want to know more about body odor, please see the comment section, which is very long, but you must read it. There are many first-hand experiences of your friends reporting.