When we hear about gender, people will think of men and women. In fact, most species on the earth are divided into male and female, and some of them are asexual reproduction. Generally speaking, asexual reproduction does not need the combination of two kinds of germ cells. The biggest advantage is that it can maintain the purity of pure cells, and people can use many kinds of plants The way to maintain the ancient varieties, such as grafting, cutting and so on, so that animals, people can achieve their wishes through cloning.
As we all know, human cells have a nucleus, so many genetic materials are located here. There are 23 pairs of chromosomes at the same time, one of which is sex chromosome. If the female is two X chromosomes, if the male is one X and one Y chromosome, then we can calculate the ratio of the two, which accounts for 50%. Therefore, the gender of human beings is actually determined by the father.
But many experiments have proved a fact that the Y chromosome is actually shorter than the X chromosome, so if a pair of parents give birth to twins at the same time, then compared with boys and girls, according to the length of the genome, the mother’s contribution must be greater. But if it is according to the type of gene, the genes on X and X are the same, but there is a code on the Y chromosome There are 27 genes in total, but there are no genes on the X chromosome, so boys have 27 more coding genes only from their fathers than girls. It seems that fathers contribute more to their sons than mothers.
So why do scientists raise the concern of human beings about the font of Y? This point was put forward by the professor of Fudan University Life Science College.
Crocodiles or larvae in nature have many ways of sex determination. If we look at human beings, how do X, y, long and short chromosomes evolve?
First of all, their evolution is probably divided into several steps. First, undifferentiated chromosomes are like two XS. Second, a special transformation has taken place at a key point in the chromosome, resulting in the emergence of new male determining genes. But in fact, most of the regions are homologous. Next, there is further special evolution, where a large number of gender genes appear, and the homologous regions become smaller and smaller. Finally, the evolution of the male determining genes is more and more complicated According to the degree of specialization and the time of origin, scientists have also found the existence of new sex chromosomes in some species.
In this process, scientists found that the Y chromosome of many organisms is less and less, and even the whole Y chromosome is completely lost. Although the male is still male, but they are not
The group has changed a lot. According to the model, a female scientist estimated that 1393 Y chromosomes had been lost in the past 300 million years
4.6 genes will be lost in almost one million years, so 27 specific sex determining genes can be found in humans, but these 27 genes may eventually disappear in more than five million years.
It seems terrible, but people will not feel very anxious because of the gender imbalance and the lack of a partner. After all, there are still more than 5 million years to go, and it is still too early for us.
Under the control of epigenetics, chromosomes and related genes always determine gender. Of course, gender in species is also affected by environment and temperature. What we can be sure is that gender staining does degenerate, but the speed of degeneration is related to many factors. Therefore, we need not worry too much about the complete disappearance of male and its characteristics.
After all, if there are gender differences, there will be combinations of different genders. In a word, no matter what individual human choices are, as long as there are gene recombination and mutation combinations, the whole earth can live forever.