Why don t half of the world s people have long tails? 80

There are two kinds of people in the world, half men and half women, so no matter whether they are men or women, they don't have long tails.

Does anyone in the world have a long tail?

This question is misleading, and it is wrong for you to play on this false proposition that half of the people have long tails.

The glyph is made up of a pinch and a pinch of the word! So half of the world's population is tailless! Hehe, if there is anything interesting in the future, notify me online! Happy every day!

Because half of them are men and half of them are women.

Khan, men have"Tail", do you understand? =.=

Reason 1: There are no "half" people in the world, so half of the people don't have long tails.

Reason 2: There are two "half" people in the world, half men and half women, so no matter whether they are men or women, they don't have long tails.

Reason 3: Because only half of the people have tails.

In general: the probability of having a boy or a girl is equal.

That's 50%.

Because the other half of the people have a tail.

There is no "half" of people in the world at all, they are all whole.

Half a man does not grow a tail.

Because half of the world's population has a tail.

So the other half of the people don't have tails -- -b

-!How can half of them 、!! It's all one person, the whole o

Because, half of the people in the world don't have zhang tails, so what about chang tails?

Because only half of them have tails.

How can there be "half" of the world's people.

Hello, contemporary humans don't have long tails, so there are no people with long tails in the world.

Our ancestors all evolved through the long-term labor of apes, and apes have tails. Later, the tail fell off. But now some people still have atavistic phenomena, people with long tails, very short tails.

Indian man Chandri Oram was a tea worker with a 13-inch tail that made him a cult figure among the locals.

Tails first evolved 500 million years ago, and they played every role you can imagine. Geckos use their tails to store fat, birds use their tails to control the direction of flight, and rattlesnakes use it to scare off predators. But for most mammals, it has one main function:

Balance. However, when the species evolved closer to humans, the tail disappeared.

Gorillas don't have tails, chimpanzees and apes don't have tails, and of course humans don't have tails. The reason for this has to do with the way we walk. Some of us primates walk on our knees with their chests diagonally to the ground; In addition, like gibbons and humans, they can walk completely upright.

Now, walking this way gives us a huge advantage.

Because unlike quadrupeds, they have to exert effort with every step. The two legs are affected by gravity, which saves us effort, and with each step we take, gravity pulls us forward. As a result, when we walk, we save 25 percent effort than walking on four legs.

In the wild, every strand of effort you save makes the difference between surviving and starving, and this way of walking completely eliminates the need for the presence of the tail. Although a human head weighs a full 5 kilograms, when a human walks, the head is above the body and not in front of it, so there is no need for a tail to balance the body.

However, our primate ancestors still had tails, and if you look at the human spine, you can see that the last few bones are partially glued together, which is the tail vertebrae. That's all we have left for our tail.

In rare cases, babies are born with something like a tail, but that's not a tail. Many times, these tails are tumors, cysts, or even parasitic twins.

More rarely, they are true branches of the spine, but it is completely devoid of bones, it is a hose made of fat and tissue. Usually, this type of tail is a birth defect, a spinal deformity called spina bifida. In these cases, doctors will perform surgery to remove the tail, which is not harmful to the baby.

The tail was originally used for balance, but in the course of human evolution, the balance was replaced by the hands, and the tail gradually degenerated. When the baby is still in the mother's womb, the tail can still be seen under ultrasound. After the baby is formed, the tail also degenerates.

However, our tail vertebrae still have the shadow of a vestigial tail. So there should be no one with a long tail, unless that person takes it out before it is formed.

This is because in the process of human evolution from animals to humans, the role that the tail can play is gradually disappearing. With the development of human evolution, the human brain is more and more developed, and the movements are more and more flexible, and the tail loses its original function, but will hinder the movement of human beings, and slowly, the tail degenerates. This phenomenon is inherited, so people don't have tails.

However, there are sometimes exceptions, because the embryo is not properly stimulated during the fetal period, and the tail cannot degenerate, so the tail phenomenon will also occur after birth.

In fact, the earliest origin of this mysterious degraded tail can be traced back to fish. In the study, the eggs of the 100-million-year-old fossilized fish Aetheretmon, the most ancient ancestor of today's land animals, were analyzed. The aetheretmon has a fleshy tail with scales and a flexible tail fin.

These two structures are completely independent. By comparing the eggs of aetheretmon with other existing fish, it was found that the two "tail" structures first grew together and then slowly began to grow independently.

Fish later evolved into semi-aquatic animals, and when they evolved into terrestrial animals, they lost their flexible tail fins. However, the fleshy tail has slowly become the tail of the dogs, cats, cows and other animals that we are familiar with. For dogs, that tail is very useful for visual communication, can also be used to chase away surrounding insects, and of course other functions.

For adult apes, including human ancestors, the tail evolution goes even further.

For better upright locomotion, humans lost the bony tail that was retained. Like fish, the remains of the bony tail in the embryo are hidden under our backs, forming the tailbone, and do not grow into the body structure of the arms and legs. As a result, human and fish embryos share a common mechanism to inhibit tail formation.

The most important point of Darwinian evolution is natural selection, survival of the fittest. But there are some traits that do not affect the survival of organisms in the process of evolution, so why do these traits disappear as well? For example, the tail of a person, the tail does not affect the survival of a person, and the process of natural selection will not eliminate people with tails, but people now do not have tails.

So I think Lamarck's theory of use and absence, because people don't need to use tails, so tails gradually degenerate.

The human tail is not because the tail makes the person with the tail eliminated, but because the effect of the tail on the person is small enough to be eliminated, the natural choice is to eliminate the tail and let it degenerate.

The development of the cerebellum and the backward shift of the center of the human body make it unnecessary for humans to rely on the tail to maintain their center of gravity and balance. So the human tail shrunk to a very small one....You touch the back of your back. The protruding part of the back end of the groin, which is the human tail, the tail vertebrae, is very short.

The tail degenerates, and man evolves.

The superfluous stuff degrades.

Man is stupid because man has no fat.

Humans evolved from apes, so they used to have tails, but according to research, the tails degenerated about 20 million years ago. The tail vertebrae in our body today are the tail that was previously degenerated.

Because humans evolved their hands, the tail lost its proper role and degenerated in the process of evolution, so humans did not have a tail.

It's not that humans don't have tails, a long, long time ago, humans actually had a long tail like monkeys, but after a long period of evolution, human tails began to get shorter and shorter, and finally shrunk to the point where they are invisible to the naked eye. But the human tail still hasn't disappeared, and it can still grow back when humans need it.

Both humans and apes do not have tails, but their ancestors, monkeys, do. The tail goes from being there to nothing, which is a degenerative phenomenon. How to explain the phenomenon of degradation was a source of great distress for Darwin.

He proposed two mechanisms: one is due to non-use or "retirement", and the other is due to natural selection. Let's look at these two mechanisms proposed by Darwin from the perspective of modern evolution.

"Use" should be taken apart and viewed: "use", that is, the frequent use of a certain organ by animals can cause this organ to become more and more developed in future generations, which is the use of acquired inheritance to explain the evolution adapted to the environment, which is in conflict with modern evolutionary theory. But "abolition" does not necessarily contradict modern evolutionary theory.

In the view of modern evolutionary theory, "decommissioning" is actually the result of the accumulation of harmful mutations after natural selection has not worked. In the case of the disappearance of the tail, for example, the genes related to the tail will always mutate in the long run, and the vast majority of mutations are harmful. But when the tail is functional, natural selection will eliminate harmful mutations and prevent them from accumulating.

But once the tail loses its function, whether it develops or degenerates has no effect on the survival and reproduction of the individual, natural selection is no longer in charge, harmful mutations are retained and accumulated, and the tail becomes smaller and shorter until it disappears. What if the disappearance of the tail is due to natural selection? That's because not having a tail has a survival advantage over a tail.

However, it is meaningless to say this, and if everything is explained by the term "survival advantage", natural selection really becomes synonymous. The key is to find out what kind of "advantages" there are. The tail is also made up of flesh and bones, and it can also hurt and bleed.

When the tail has a function, an injury, bleeding have to endure. But once the tail becomes a dispensable liability, it will be injured and bleeding will become a survival disadvantage. What's more, the cells that make up the tail need to be metabolized and need to be nutritious**; Walking with a tail also consumes extra energy.

Wouldn't it be better if we could save the nutrients and energy that are given to useless tails and distribute them to more important organs, such as the brain? Therefore, in this case, natural selection favors the tailless ones and the tailless ones are eliminated.