Why do people have 10 fingers?

It doesn't matter if you grow more, but you need at least 5 to complete complex biological functions. In the case of people, for example, the work that can be done with the thumb and index finger is difficult for you to do with the index and middle fingers. It's not that other numbers are generally more difficult to understand, but to be clear, not 6 fingers will be more flexible than 5, but 4 will obviously not be enough.

The organism is a system that maximizes the effect, so the 5 fingers have the best price-performance ratio, and in the end 5 fingers are kept. This is why there are very few ten-fingered creatures in the ocean, while almost all terrestrial creatures are ten-fingered. It's useless if you don't agree, I'm a zoology major, and if you get a high score, maybe I'll tell you why the ring finger can't be missing.

In fact, at present, for the palm of the human hand, the ring finger does not have a particularly big effect, but don't forget that humans evolved from animals, so the current human ring finger only has evolutionary significance and is used to wear wedding rings. But for humans before evolution, for example, I take orangutans or cheetahs as an example, cheetahs have no hands, their daily life is to hunt and eat, if it is 4 fingers, according to the principle of mechanics, he can't run fast, and his center of gravity will be unstable when making sharp turns (this person is the same, you don't believe that you can try to run at home, when you turn a corner, you feel the power on the soles of your feet where it is concentrated, but don't expect your toes to feel it, because he is also degenerate). And for the orangutan, his 4 fingers when he climbs a tree is also an unstable state, and if he is targeted by a cheetah, he will not stop running.

It's that simple. Having said that, even if the ring finger of human beings is now degenerate, when you hold a water cup, when you carry a school bag, and when you do fine movements, you will find the auxiliary role of the ring finger.

Ten fingers are useful, and ten fingers are easy to do.

Generally, everyone has 10 roots, and there are more and less.

The fact that humans have 5 fingers is entirely due to evolutionary history, the apes before humans had 5 fingers, and the older amphibians also had 5 fingers, and humans inherited this trait due to genetic reasons, and some people with 6 fingers can also be seen by chance.

Terrestrial vertebrates have a common evolution**, from a structural point of view, whether it is a reptile or a mammal, there are basically upper and lower jaws and front and rear limbs, and the structure of both has some similarities, indicating that terrestrial vertebrates may have a common evolutionary origin, scientists believe that flesh-finned animals climbed onto land after a long time of evolution and differentiation, and found in our country the most distant amphibians, they are considered to be an important specimen of the evolution of flesh-finned to amphibians.

Flesh-fins are characterized by a spine that connects the head to the tip of the tail and four strong fins, there are bones in the fins, when they come to the land, adapt to the life of the land, the bones in the fins gradually differentiate and segment to form a creature similar to the structure of the limbs of modern reptiles and mammals, some bones at the end of the limbs gradually evolve into the muscles of the palm and the structure of the 5 fingers, which is an accidental change, caused by the non-directional mutation of genes, all species with this characteristic have a common ancestor. In fact, except for the thumb, the other four fingers have less than one and more than one on the activity of the human hand, which does not have a particularly large impact on the activity of the human hand.

Primates inherited this characteristic after the emergence and evolved into a more flexible structure that can hold objects, and an important reason for the differentiation in the evolutionary history of humans and other primates is the division of labor between hands and feet, the division of labor makes the legs as the main structure to support the body, freeing the hands to pick up objects on the ground as temporary **, and over time there are tools made by themselves, **, and the hands can carry out a lot of delicate activities, which is also reflected in the cerebral cortex, Correspondingly, the more complex and delicate the activity of a certain part, the larger the area of the cerebral cortex required to regulate its movement, so the nerves in the human hands, eyes, mouth, etc. are quite abundant, the former meets the needs of movement, and the latter meets the expression of emotions.

There are also a very small number of human populations due to the embryonic stage or heritable variation from the parents, so that the development of the hand encounters an "obstacle" that connects the fingers, like the fins of sea creatures, or a few more roast chicken root fingers, as long as the bone structure in the fingers is at night, it does not affect the normal activities of the person. However, the sixth finger of many six fingers is like a granule, which plays a small role and is even an obstacle to daily life.

The construction of 5 fingers is a coincidence, and this coincidence is also related to the development of human mathematics, the construction of 10 fingers and 10 toes makes human mathematics naturally appear in the decimal counting method, which is convenient for technology and calculation.

This is due to the differentiation of people. The 5 fingers are the most conducive to human work and doing something. So when it is differentiated, it is 5 fingers.

Because it is most scientific for a person to have 5 fingers, it is more conducive to the use of tools, so a person will have 5 fingers.

Because this is genetically determined, it is more convenient to have 5 fingers as the environment changes, so humans have evolved to have 5 fingers.

The 10-centimeter reference has a dollar coin, a 5-inch mobile phone, a bank card or ID card, a lighter, etc。The most convenient is our palm, plus the width of the palm of the thumb is 10 cm. There is also a lighter for daily use that is about 9 centimeters long, which is 10 centimeters the width of a small thumb.

The centimeter is a metric unit, which is what we usually call the centimeter, and the unit of measurement is a measure that people choose to measure a certain type of measurable size, and its value is determined by the definition of the unit.

Ten centimeter reference introduced

The diameter of a one-yuan coin is centimeters, so the four one-yuan coins are lined up together is 10 centimeters, and there is a more direct one that the diagonal of our ID card is actually 10 centimeters, but the most convenient is our palm, plus the width of the palm of the thumb is 10 centimeters.

A 5-inch mobile phone is actually not very long in our daily life. The length of the 5-inch mobile phone is about equal to more than 11, and the difference between 10 is not very huge, if it is within the margin of error, the 5-inch mobile phone is about 10, and the length of the 5-inch mobile phone is also equal to 10 in addition to the length of 4 side-by-side coins.

If you take a 5 cent banknote to measure the diagonal of the bank card, you will find that in fact, the length of the two diagonals of the bank card and the length of the 5 cents are basically the same, so the length of the diagonal of the bank card is actually about 10.

This starts with the evolution of the limbs, you know, the limbs in the beginning were not five toes.

The first animals with limbs were amphibians, and their limbs evolved from the fins of fish, and all subsequent vertebrates had their limbs here.

The evolution of vertebrates from fins to four-legged limbs (the first limbs were not five-toed).

The first animals that could be counted as legged were true palm-finned fish, and although they appear to have only fins (flesh fins), the bones inside those fins already have basic leg features.

True palm-finned fish bones.

Later, the fish stone newt that actually climbed onto land evolved more developed than the true palm-finned fish. The legs of the fish newt have clearly divided the thighs and calves, and although the knee joints are not very flexible, they can also lift their bodies.

Fish newt skeleton.

After lifting its body, the weight falls on all limbs, and the clever short-fingered digging columnodont adopts the strategy of keeping the knee joint in a stable flexed state, dividing its weight equally among the limbs. Their knees are bent outward, but they can crawl with ease.

Short finger digging for columnodont bones.

In order to adapt to running and climbing, Archaeopteryx evolved forward-facing knees, which had the ability to flex and extend. As the climbing activity increases, the center of gravity gradually falls on the hind limbs as it travels.

Archaeopteryx bones.

The center of gravity is moving further and further back, and the forelimbs can be slowly freed for other tasks, and the Pulgatori monkeys living in the trees can already grasp the branches. Although it looks like a squirrel, it is actually one of the most primitive primates.

Pulgatori monkey skeleton.

As the brain evolved, the brain volume gradually increased, and our ancestors began to evolve in the direction of upright walking, and the lower limbs became more and more stable in order to bear the weight of the body, while degrading many skills that were not commonly used, such as the ankles were not as flexible.

Great ape skeleton (right).

About 300,000 years ago, Homo sapiens was able to walk completely upright, and the leg bones were no different from those of our modern humans.

Homo sapiens skeleton.

A person has five fingers in one hand, and ten fingers in one hand. Of course, there are six-fingered people, but this is the exception. One might ask, why do people have five fingers on one hand instead of six or four?

The general answer is evolution. If a person is missing a finger, he cannot do more complex and delicate movements, such as writing, knitting sweaters, typing, etc. But what if you had one more finger?

That can only be said that this is redundant, cumbersome and occupies space, but also attracts nutrients and wastes food. In short, whether it is a simple or complex movement, five fingers are enough, and six is too much. That's why people have five fingers on one hand.

Speaking of fingers, that foot also has five toes, and the foot doesn't have to do complicated manipulations, so why five instead of six or four? This is naturally the result of evolution, according to the weight of the person, the sole of the human foot should not be too small and not too large, then the five toes at the front of the foot bearing weight is also the most appropriate, more is too slender is not conducive to bearing weight, easy to break. Missing toes can be too big and affect flexibility.

Some people wonder what flexibility is needed if the feet are only a walking function? In fact, if you have complex actions such as rock climbing and tree climbing, the flexibility of your toes comes into play.

We can only say that nature is really wonderful, and all the objects in the world, its existence must have its raison d'être. It exists in this way and its reason for existing in this way.

You must know why people have five toes, and that's pretty much the same as the question you asked.

Because some people are born with 5 fingers (don't spray if you don't like it) (pure nonsense).

This is evolved, that is, for the need to survive. In other words, why did many animals come up from the sea in ancient times, all for survival, why did animals have tails and people were useless, they were for balance, and humans relied on their arms. In short, to adapt to nature.

Because it's human! So five fingers long

The length of 12 fingers is six-fingeredly.

Hexadactyly is a dominant disorder of the sex chromosomes (not autosomes), which is on the X chromosome. If the patient is male, there is a 50% chance that he will have offspring with a normal woman (normal in boys, hexadactyly in girls); If the patient is female, there are two types of complete dominance, with a 100% chance of developing the disease in children born to a completely dominant patient and a 50% chance of developing the disease in children born to a normal man (the same chance for boys and girls).Therefore, the probability of inheritance of hexadactyly is very high, and it is inherited with concomitant sex, so if the close relatives are married, the probability of developing the disease will increase.

Finally, it is recommended that male patients have a better boy (see above for the reasons).

It's like your feet have ten toes.!?

In Bordeaux, there is a middle-aged man named Lavigny, whose 10 fingers are born like thumbs, which is very novel? Lavigny works for a computer company and gets weird looks when he walks down the street every day, but is he used to it?

What bothered him was that the 10 thumbs could not be used as flexibly and freely as ordinary people, like tying shoelaces with his hands? He needs the help of his gentle and beautiful wife, Mary Sophie, and other daily chores that are easy for others, such as buttoning buttons and holding a pen, and as for other daily chores, he can handle them easily? It's hard to believe that Lavigny's 10 finger prints are exactly the same, and many people can't believe their eyes when they look at them?

Ten fingers as long.

The nails are about millimeters long every day, and the longer the fingers of the hand are closed, the faster the growth rate of the nails; The shorter the fingers, the slower the growth rate of the nails. That is, on the same hand, the nails of the middle finger grow the fastest, and the thumb and little finger grow more slowly. Destruction.

The growth rate of nails is related to the temperature, therefore, nails grow faster in summer than in winter, day and night, and faster in the south than in the north. Newborn nails grow more slowly, growing fastest in young adults and slower again in old age. Usually, people who are strong and well-nourished have nails that grow a little faster than people who are weak and sick.

People who use their right hand regularly will also have their right fingernails grow faster.