WHY do men have nipples?
Body structures are shaped by chemical signals. In particular, sex hormones control the formation of secondary sexual characteristics.
However, at the time of mammary glands in embryos there are no sex glands, so the ratio of male and female sex hormones in embryos of both sexes is the same and is determined by the hormonal background of the mother.
Body structures are shaped by chemical signals. In particular, sex hormones control the formation of secondary sexual characteristics.
However, at the time of mammary glands in embryos there are no sex glands, so the ratio of male and female sex hormones in embryos of both sexes is the same and is determined by the hormonal background of the mother.
π5
WHY is hugging beneficial for your health?
Researches have found that physical contact, including hugs, reduces the levels of stress hormones in the body, such as cortisol.
High levels of stress hormones can cause a number of health problems such as sleep disorders, unhealthy skin, obesity, reduced immunity and more.
Researches have found that physical contact, including hugs, reduces the levels of stress hormones in the body, such as cortisol.
High levels of stress hormones can cause a number of health problems such as sleep disorders, unhealthy skin, obesity, reduced immunity and more.
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WHY does a wet dog start to stink?
This smell varies in intensity from breed to breed depending on the type of coat, but all dogs do smell significantly more "fragrant" when wet. The reason is quite simple: water evaporating from the coat saturates the air with molecules of substances each dog's hair is covered with.
And since a dog's liquid sweat only comes out on its paw pads and the tips of the nose, sweating is not a thermoregulatory function, much of that role is taken over by salivation. Nevertheless, every hair of a dog's coat is associated with a sebaceous gland and a sweat gland.
This smell varies in intensity from breed to breed depending on the type of coat, but all dogs do smell significantly more "fragrant" when wet. The reason is quite simple: water evaporating from the coat saturates the air with molecules of substances each dog's hair is covered with.
And since a dog's liquid sweat only comes out on its paw pads and the tips of the nose, sweating is not a thermoregulatory function, much of that role is taken over by salivation. Nevertheless, every hair of a dog's coat is associated with a sebaceous gland and a sweat gland.
π₯1
WHY are there many drugs against bacterial infections and few against viral ones?
A bacterium is an integral single-celled organism which biochemistry is quite different from that of humans. Therefore, it is possible to find drugs that block the enzymes vital for bacteria or destroy their cell wall, while being harmless or minimally toxic for humans.
A virus, on the other hand, is much simpler, and after infecting the target cell, it has nothing of its own except for the genome. Genome duplication and synthesis of viral proteins are performed by the same molecular mechanisms of the infected cell that ensure the vital activity of healthy cells.
A bacterium is an integral single-celled organism which biochemistry is quite different from that of humans. Therefore, it is possible to find drugs that block the enzymes vital for bacteria or destroy their cell wall, while being harmless or minimally toxic for humans.
A virus, on the other hand, is much simpler, and after infecting the target cell, it has nothing of its own except for the genome. Genome duplication and synthesis of viral proteins are performed by the same molecular mechanisms of the infected cell that ensure the vital activity of healthy cells.
π2π€©1
WHY does water recede from the coast before a tsunami hits?
In particular, a wave is formed that differs from an ordinary wind-driven wave in that it is enormously long. While ordinary wind-driven waves are 100-200 meters long, tsunamis can be tens or hundreds of kilometers long.
The most significant metamorphosis occurs with a tsunami wave when it "bumps" into shallow water, closer to shore. Its speed, which in the open ocean was comparable to the speed of a jetliner (800 km/h), decreases, but its height sharply increases. However, we should bear in mind that in addition to the high crest of the wave rushing towards the coast there is the "sole", that is, the lowest point below the level of calm water. If the "sole" attacks the shore first, the coastal water level drops, exposing meters or even kilometers of the bottom.
In particular, a wave is formed that differs from an ordinary wind-driven wave in that it is enormously long. While ordinary wind-driven waves are 100-200 meters long, tsunamis can be tens or hundreds of kilometers long.
The most significant metamorphosis occurs with a tsunami wave when it "bumps" into shallow water, closer to shore. Its speed, which in the open ocean was comparable to the speed of a jetliner (800 km/h), decreases, but its height sharply increases. However, we should bear in mind that in addition to the high crest of the wave rushing towards the coast there is the "sole", that is, the lowest point below the level of calm water. If the "sole" attacks the shore first, the coastal water level drops, exposing meters or even kilometers of the bottom.
π€©2π1
WHY can we carry no more than 100 ml of liquids in a hand luggage?
It turns out that the "100 ml" rule has been in effect at European airports for more than 12 years.
This rule first appeared in Europe after an incident at a British airport β police arrested a group of criminals with liquid bombs.
It was then that it was considered liquids in containers of up to 100 ml and a total volume of up to 1 l do not pose a threat β roughly speaking, with that volume of flammable liquid on board, a dangerous ignition is unlikely.
It turns out that the "100 ml" rule has been in effect at European airports for more than 12 years.
This rule first appeared in Europe after an incident at a British airport β police arrested a group of criminals with liquid bombs.
It was then that it was considered liquids in containers of up to 100 ml and a total volume of up to 1 l do not pose a threat β roughly speaking, with that volume of flammable liquid on board, a dangerous ignition is unlikely.
WHY do people actually want to settle on Mars but not in Antarctica?
Mars is a challenge and a prospect on a different scale
False to think that other planets will save us from overpopulation. Neither Mars nor Antarctica will help unless population growth stops.
Living in Antarctica is already possible: 1000 to 4000 people permanently stay at scientific stations there. However, everything keeps on supplying from the Big Earth.
On Mars, the habitat should be relatively autonomous, requiring almost no Earth support. This is a colossal technological challenge, the acceptance of which could trigger technological progress.
Mars is a challenge and a prospect on a different scale
False to think that other planets will save us from overpopulation. Neither Mars nor Antarctica will help unless population growth stops.
Living in Antarctica is already possible: 1000 to 4000 people permanently stay at scientific stations there. However, everything keeps on supplying from the Big Earth.
On Mars, the habitat should be relatively autonomous, requiring almost no Earth support. This is a colossal technological challenge, the acceptance of which could trigger technological progress.
WHY are movies shot against a green background?
The green background is used in films in order to replace it with computer-generated visual effects: a single-color green canvas transforms into a panorama of the city, for instance, during the post-production phase.
Technically, the background color can be anything - gray, white, black or purple, but films are shot against a green background, as this color stands out the most (that is, it is easier to highlight and replace it with another color or image later on).
The green background is used in films in order to replace it with computer-generated visual effects: a single-color green canvas transforms into a panorama of the city, for instance, during the post-production phase.
Technically, the background color can be anything - gray, white, black or purple, but films are shot against a green background, as this color stands out the most (that is, it is easier to highlight and replace it with another color or image later on).
WHY do people grab their earlobe when their finger is burned?
The earlobe is the coldest part of the body (available), and it is normal to look for something colder when burned.
Moreover, the lobe has many different receptors, so they are projected to certain internal organs of our body and warming the burned fingers on the earlobe helps to reduce the pain.
The earlobe is the coldest part of the body (available), and it is normal to look for something colder when burned.
Moreover, the lobe has many different receptors, so they are projected to certain internal organs of our body and warming the burned fingers on the earlobe helps to reduce the pain.
WHY do wounds itch when they heal?
The injured tissue releases the neurotransmitter histamine abundantly. Immediately after injury, it triggers an inflammatory response and later prompts tissue stem cells to migrate to the damaged area and repair the tissue.
It turns out that histamine irritates the nerve endings in the skin, causing itching.
The injured tissue releases the neurotransmitter histamine abundantly. Immediately after injury, it triggers an inflammatory response and later prompts tissue stem cells to migrate to the damaged area and repair the tissue.
It turns out that histamine irritates the nerve endings in the skin, causing itching.
π1
WHY are there wooden planks on F1 cars?
Formula 1 cars have been continuously improved to increase downforce, which has been achieved, among other things, by minimizing ground clearance.
Since 1994, to combat accidents and improve safety, a simple 10mm thick beech wood composite board has been mandatory on the underside of all racing cars. After the race, the boards are always checked, and for wear and tear beyond the allotted limit, the driver's result may be invalidated.
Formula 1 cars have been continuously improved to increase downforce, which has been achieved, among other things, by minimizing ground clearance.
Since 1994, to combat accidents and improve safety, a simple 10mm thick beech wood composite board has been mandatory on the underside of all racing cars. After the race, the boards are always checked, and for wear and tear beyond the allotted limit, the driver's result may be invalidated.
π1
WHY is dieting incompatible with alcohol?
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It's not even so much that alcohol increases appetite and lowers self-control, but that the brain, having detected the presence of ethyl alcohol in the blood, stops the metabolism, including the process of turning fat into glucose, and concentrates on removing alcohol and its toxic derivatives from the body as quickly as possible.
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Since your body is capable of absorbing no more than 15 to 30 ml of pure alcohol per hour, the process of digesting a can of beer, for example, will stop fat burning for about an hour and a half.
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It's not even so much that alcohol increases appetite and lowers self-control, but that the brain, having detected the presence of ethyl alcohol in the blood, stops the metabolism, including the process of turning fat into glucose, and concentrates on removing alcohol and its toxic derivatives from the body as quickly as possible.
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Since your body is capable of absorbing no more than 15 to 30 ml of pure alcohol per hour, the process of digesting a can of beer, for example, will stop fat burning for about an hour and a half.
WHY are drinks carbonated?
Carbonated beverages are drinks saturated with carbon dioxide, characterized by a peculiar, beloved by many taste, refreshing properties and the so-called sparkling, i.e. intensive and prolonged release of gas bubbles.
In addition to the special taste, the main commercial property of carbon dioxide - preservative (disinfecting, disinfectant, antimicrobial) - is intensively exploited in the production of beverages today.
Carbonated beverages are drinks saturated with carbon dioxide, characterized by a peculiar, beloved by many taste, refreshing properties and the so-called sparkling, i.e. intensive and prolonged release of gas bubbles.
In addition to the special taste, the main commercial property of carbon dioxide - preservative (disinfecting, disinfectant, antimicrobial) - is intensively exploited in the production of beverages today.
π€©1
WHY can some fungi turn ants into zombies?
Some parasites are capable of dramatically altering their host's behavior to achieve their goals, turning it into a zombie.
These include the cordyceps lopsided fungus, which penetrates the ant's body and then somehow forces the insect to follow a place optimal for the parasite's development.
The ant seeks out the plant, climbs to a height of 20-30 cm, finds a leaf with a certain temperature and humidity, and bites into the central vein on the underside of the leaf. The ant then dies and the fungus sprouts from its body.
Some parasites are capable of dramatically altering their host's behavior to achieve their goals, turning it into a zombie.
These include the cordyceps lopsided fungus, which penetrates the ant's body and then somehow forces the insect to follow a place optimal for the parasite's development.
The ant seeks out the plant, climbs to a height of 20-30 cm, finds a leaf with a certain temperature and humidity, and bites into the central vein on the underside of the leaf. The ant then dies and the fungus sprouts from its body.
π±7π2
WHY does a person need privacy?
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A person should be alone for at least two hours a day staying in a state of peace. It is just as vital for mental health as communication.
The smooth flow of thoughts, self-knowledge and reflection, sometimes just emptiness and silence - we tend to do this unknowingly, but we need the solitude.
On the way to and from work, disconnecting from the world in public transportation, idly looking at storefronts, not planning to shop, etc. We need solitude to balance our souls.
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A person should be alone for at least two hours a day staying in a state of peace. It is just as vital for mental health as communication.
The smooth flow of thoughts, self-knowledge and reflection, sometimes just emptiness and silence - we tend to do this unknowingly, but we need the solitude.
On the way to and from work, disconnecting from the world in public transportation, idly looking at storefronts, not planning to shop, etc. We need solitude to balance our souls.
β€8π3
WHY is it quiet outside when it's snowing?
Sound is a mechanical oscillation of a certain frequency that propagates in solid, liquid, and gaseous media. As the layer of freshly fallen snow grows, more and more empty cells containing air appear between the snowflakes.
Sound waves hitting the snow layer are not reflected from it as well as, for example, from a solid homogeneous surface, and some of them are absorbed by the snow cover. But if the snow settles, the number of air cells will immediately decrease, and the sound can be better reflected from the surface.
That's why it's quietest outside when the snow is still soft and freshly fallen. After a few hours, the snow cover thickens, and the amazing silence and charm of the snowfall dissipates.
Sound is a mechanical oscillation of a certain frequency that propagates in solid, liquid, and gaseous media. As the layer of freshly fallen snow grows, more and more empty cells containing air appear between the snowflakes.
Sound waves hitting the snow layer are not reflected from it as well as, for example, from a solid homogeneous surface, and some of them are absorbed by the snow cover. But if the snow settles, the number of air cells will immediately decrease, and the sound can be better reflected from the surface.
That's why it's quietest outside when the snow is still soft and freshly fallen. After a few hours, the snow cover thickens, and the amazing silence and charm of the snowfall dissipates.
π€©2
WHY do champions adore to bite their medals?
Athletes first decided to bite their medals in 1991. The British steeplechase team did it. As the athletes admitted, the photographers asked them to do something weird and amusing for the frame, as the traditional posing with the award was no longer so interesting.
According to some historians, metal biting began back in the Middle Ages. Allegedly thatβs how pirates tested gold coins for authenticity. Gold is soft enough, so the dent marks caused by the teeth must have remained on the precious metal. For comparison, gold has a hardness of 2.5, silver 2.7, and platinum 4.3.
Athletes first decided to bite their medals in 1991. The British steeplechase team did it. As the athletes admitted, the photographers asked them to do something weird and amusing for the frame, as the traditional posing with the award was no longer so interesting.
According to some historians, metal biting began back in the Middle Ages. Allegedly thatβs how pirates tested gold coins for authenticity. Gold is soft enough, so the dent marks caused by the teeth must have remained on the precious metal. For comparison, gold has a hardness of 2.5, silver 2.7, and platinum 4.3.
π1
WHY are the buttons on men's shirts sewn on the right but the ones on women's shirts stitched on the left?
High society women used to dress with the help of maids. It was easier for the helpers to button the buttons, so they were placed on the left side.
Men, on the other hand, preferred to dress themselves, so it was more convenient for them to have the buttons on the right.
Men used to carry weapons on the left side, so the left shelf was on top of the right, so the hand wouldn't cling to the clothes. It was also easier to reach for a weapon that was under his clothes with this option. If a man was already holding a weapon, it was easier for him to unbuckle his clothes with his left hand. In cold weather, men could keep their right hand, which held the weapon, warm under the left hem.
High society women used to dress with the help of maids. It was easier for the helpers to button the buttons, so they were placed on the left side.
Men, on the other hand, preferred to dress themselves, so it was more convenient for them to have the buttons on the right.
Men used to carry weapons on the left side, so the left shelf was on top of the right, so the hand wouldn't cling to the clothes. It was also easier to reach for a weapon that was under his clothes with this option. If a man was already holding a weapon, it was easier for him to unbuckle his clothes with his left hand. In cold weather, men could keep their right hand, which held the weapon, warm under the left hem.
π10π±2
WHY do mirrors change left to right, but not up to down?
The mirror is not aware of your position; it simply reflects the light that hits it. Then why, when the reflected light hits your eye's photoreceptors, does your image change from left to right?
Actually, the question of what makes the horizontal axis so special in the context of a mirror is itself incorrect. The fact is that the mirror does not reflect from left to right or top to bottom, but it does reflect backwards.
In other words, your mirror reflection is not reversed, but inverted into the third dimension, like a glove being turned inside out.
The mirror is not aware of your position; it simply reflects the light that hits it. Then why, when the reflected light hits your eye's photoreceptors, does your image change from left to right?
Actually, the question of what makes the horizontal axis so special in the context of a mirror is itself incorrect. The fact is that the mirror does not reflect from left to right or top to bottom, but it does reflect backwards.
In other words, your mirror reflection is not reversed, but inverted into the third dimension, like a glove being turned inside out.
β€2
WHY does metal ring?
When deformed slightly, forces arise in the metal, tending to restore its original shape. However, these forces "bend the stick": the metal skips the equilibrium position and deforms in the opposite direction with acceleration. Then the elastic forces change direction, and everything repeats.
Sound vibrations arise, which pass from the metal to the air. The frequencies of the vibrations depend on the elastic properties of the material as well as the mass and shape of the object made of it. Predicting how a particular object will ring is not easy.
When deformed slightly, forces arise in the metal, tending to restore its original shape. However, these forces "bend the stick": the metal skips the equilibrium position and deforms in the opposite direction with acceleration. Then the elastic forces change direction, and everything repeats.
Sound vibrations arise, which pass from the metal to the air. The frequencies of the vibrations depend on the elastic properties of the material as well as the mass and shape of the object made of it. Predicting how a particular object will ring is not easy.
π3