After 10 million years, the Y chromosomes that determine the gender of human beings will disappear. What would human beings happen at that time?

It seems that it is not a secret that the Y chromosomes of human men are disappearing. However, as we all know, human beings, like many mammals, are determined by Y chromosome to determine gender.

Then the question comes. If the Y chromosome disappears, what does it mean for humans?Gender disappear?Or is there more wonderful things?

Why is the Y chromosome disappear?

Regarding how Y chromosome determines gender, it is very clear now. In 1990, scientists identified some special genes on the Y chromosome -named Sry gene (gender area on Y).

Sry gene is a transcription factor. About 12 weeks after conception, it starts other genes that regulate testicular development to promote testicular development, and then embryo testicular androgen produces male hormones and ensure that the fetus develops into a boy.

Although Y chromosomes have an indispensable role in gender decisions, the effects of the entire Y chromosome on other traits can be said to be minimal.

Figure: Human sex chromosome gene status

Because its homologous chromosomes, X chromosomes have more than 1,000 genes, and Y chromosomes actually have only 45 genes, and a large number of non -coding DNA (some simple repeated DNAs that have no practical effects).

For most mammals, it is basically the same in terms of gender decisions. It is determined by Sry genes on the Y chromosome, and the reflection of Y dyed is basically the same -there are few genes carrying.

However, there are two kinds of mammals.

The first is the primitive mammal like duckbill.

Although the duck brave beasts have evolved to nurture offspring with breast milk, they do not have placenta or parenting bags, but they are oval like reptiles.

By observing the genetic information of the duck billes, they are not a single XY chromosome to determine gender. In fact, they have multiple X and Y chromosomes, which together determine the gender of the braills, which are unique in vertebrates.

In addition, the XY chromosomes of the duck brail beast are not as "not equal" as other mammals. Among the cells of the duck bilies, the XY chromosomes are more like an ordinary homologous chromosome.Essence

From the example of the duckbill beast, scientists speculate that two possibilities. The first is that a single determination of gender Y chromosomes appeared after mammals appeared.Chromosome should be basically the same.

Figure: Several animal separation time existence on the earth

The ancestors of duckbill beasts and existing mammals began to part ways about 166 million years ago. They evolved each other. Some scientists calculated the "degradation" of human Y chromosomes at this time.

About an average of 4.6 genes lost 4.6 genes per 1 million years, so the remaining 45 genes are almost 10 million years, which may be the life of human Y chromosomes.

However, it is obvious that this calculation method is very rough, so how much time can there be in the specific time of human Y chromosomes -now, there is a saying that the data I found will never disappear from thousands of years to never disappear.

Although many people believe that Y chromosomes will never disappear, more people still believe that it will really disappear. After all, almost all mammal Y chromosomes do have this potential.

Without Y chromosomes, men will disappear, and mammals cannot directly produce offspring through their own genes with their own genes -because at least 30 "mark genes" must come from male.

So does this mean that many mammals, including humans, end the end of the "male disappearance"?

Well, good news may not happen, because the Y chromosomes of mammals in nature have completely disappeared, but they are not extinct.

These mammals that lose Y chromosomes are the second mammals that do not use the XY gender determination system without using the XY gender decision.

Amato Kuroiwa

What about losing Y dyeing experience?

There are currently two kinds of mammals that do not have Y chromosomes. One is the TOKUDAIA Osimensis found on Amami Island, Japan, and the other is Ellobius Tancrei in Eastern Europe.

The females and males of these two kinds of mammals have only one X chromosomes. This former "sex chromosome" does not match the chromosomes that are paired with themselves, exist in a single form, but animals still appear female and male.

Many people may be curious, how can they survive normally when they lack a chromosome.

In fact, this is normal, especially like Y chromosomes in itself, there are few genes, and things that can be determined are limited. What is really strange is how they can still have male and female.

In fact, there is indeed a man with XX chromosomes in humans, and there are also women who are female. This is indeed a sexual reversal syndrome.

Sexual reversal syndrome is much more than expected. For example, for the XX men, about one of the 20,000 people is like this.

In humans, men do not need Y chromosomes. In fact, the reason is particularly simple because the sry gene on Y dyed is transferred to other chromosomes when dividing and dividing.

As long as there is sry gene, it can activate the development of the testicles, and naturally appears, but the two animals we mentioned earlier have no Y dyed and no SRY gene.

Now no one knows how they develop gender, this is still a fan, but these two examples can tell us that the ending of mammals is not so sad.

The Japanese scientific research team conducted a long study of Amami Strang and completed gene sequencing. Although they did not find any unique mutations in male, they claimed to have discovered a more interesting fact, that is, the Amami Strang Rat RatsOne of the two copies of the No. 3 chromosome is a duplicate area, just next to the SOX9 gene.

We mentioned earlier that Sry genes activated other genes before eventually leading to testicular development, and its activation way is to start with SOX9 gene.

Eastern field mouse

This mutation is likely to be the reason why the Amami Stranging Rat still has a gender without the SOX9 gene. Therefore, they define No. 3 chromosome as Proto-X and Proto-Y (primitive XY stain).

Can the 3 chromosomes of the Amami Stranging mouse be confirmed by more research, but if this is the case, the pair of chromosomes may experience the previous XY process again -Y chromosomes are constantly shortened.

Humans may also go through this process. After about 10 million years, perhaps a Y chromosomes in the human breeds completely disappear, leaving only one X chromosome to continue to reproduce.

You may also be curious about the remaining X chromosome, what will happen?

There may be two possibilities. One is that it either disappears, because chromosomes without pairing, and its mutations will accumulate quickly over time. This is not conducive to survival.Only extinction.

Northern mouse

Another possibility is a chromosomes that are paired, just like the close relatives of the east mouse now -northern mice, they also have no Y chromosomes, but their male and female have XX chromosomes.

Of course, these are just guessing. After all, the disappearance of human Y chromosomes in human beings still has a lot of controversy. In the short term, there is indeed no evidence that there is a powerful evidence that it has some instability that will continue to "degenerate".

However, no matter what the ending, this is a long process. There is a huge difference in the species and the present at that time, and there is a huge difference in genetic, and it can only be divided into different species.

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