In order to ensure the normal reproduction of species, nature has evolved reproductive isolation.
Reproductive isolation means that groups of closely related relatives do not mate under natural conditions, and even if they do, they cannot produce offspring, or they cannot produce normal offspring.
For example, we are most familiar with mules, and as the offspring of horses and donkeys, mules cannot produce the next generation. But why is there no reproductive isolation between the yellow race, the white race, and the black race? Is it better than human beings, who have broken through the reproductive segregation?
This is illustrated by the example of humans versus chimpanzees. Although humans and chimpanzees are highly similar in genetically, there are 23 pairs in humans and 24 pairs in chimpanzees due to the different number of chromosomes. Don't underestimate such a difference, this has become an important obstacle to the reproduction of both sides.
In addition to the unequal number, this will lead to the combination of the two germ cells, there will be a situation of more monks and less porridge, and the final result is either malformation or infertility.
The chromosomal composition between the two is not the same, which means that the germ cells of both sides are unable to work together deeply and complete the most basic pairing.
That is, humans did not break through reproductive isolation. So why do different races mate and reproduce normally?
First of all, the conditions for forming reproductive isolation are not as easy as everyone thinks, although human beings have evolved various ethnic groups such as Caucasians, yellow people, and black people, it is still difficult to achieve the necessary conditions for reproductive isolation.
In 2010, researchers in genetics and molecular science found that all people's genetic chromosomes have one of the most primitive commonalities. And this common denominator is said to have emerged as early as 100,000 years ago. At that time, all human beings lived in East Africa.
Then, 100,000 years ago, some humans migrated to Europe, and 70,000 years ago, some humans migrated to East Asia and even the world, and it was 70,000 years ago that humans began to appear in a variety of skin colors. At this time, we humans are in the late Homo sapiens stage.
Neanderthals, who had gone out to see the world 1.1 million years earlier, felt that he had gone to a foreign country to gild, he felt that he was strong, and then a great war broke out with late Homo sapiens.
Competition between species is not unusual, but the point is that we humans have 4% Neanderthal genes in our genes. This shows that it is very likely that late Homo sapiens and Neanderthals will talk about having children together. But at this time, the two have been separated for 1.1 million years.
For such a long time, the two primitive human races still have not formed reproductive isolation, not to mention, people of different skin colors have only been fighting for 70,000 years, and if you want to achieve reproductive isolation, the time is indeed a bit too short, at least a few million years.
And secondly, what is the most important thing to reproduce? Yes, that is genes, but the genes of our human beings, the genes of all races of human beings are basically the same. That is, mitochondrial DNA and Y chromosomes, whether it is a yellow person, a white person, or a brown person, the main components of the gene will not change.
Since the main components of genes cannot be changed at present, it is natural that no matter how long the isolation isolation, reproductive isolation will not occur. Coupled with the fact that it is now basically globalized, and people around the world are becoming more and more connected, it is more difficult for people of different colors to have reproductive segregation as they become more connected, without geographical segregation.
Finally, what is needed for reproductive isolation is that after a long period of evolution from generation to generation, the two populations first change the gene pool, and then change the proportion of a specific gene in this ethnic group, and finally form two different subbodies, the so-called subbodies, which can be understood as defective products before the product leaves the factory. In the end, these two groups each evolved new species.
However, in fact, whether it is black or white, or yellow, after all, they all belong to the same species of mammalian primates, not a new species, in short, the current human population, but only a small repair, has not yet reached the point of drasticism, because it belongs to the same species, there is naturally no reproductive isolation.
Since human reproductive isolation has nothing to do with skin color differences, how did human skin color differences appear? It may be the result of adapting to the external environment.
At present, there is a saying that human beings originated in Africa, because Africa is located at the equator and is very hot, so in order to protect their skin from the sun's ultraviolet rays, human beings will secrete a large amount of melanin, which is also the reason why Africans are very dark.
When ultraviolet rays hit melanin, melanin will shake these ultraviolet rays away at a super fast speed, and 99% of the ultraviolet rays will be shaken to the point that only heat remains.
Later, when humans migrated to Asia, especially Europe, the sun's ultraviolet rays were no longer so powerful, so melanin slowly degraded without any use, such as the current European Caucasians.
Secondly, different races have different skin colors, and personal speculation may be the result of genetic mutations, and the migration span of primitive humans is very large, so there are Europeans, Asians, Africans, and so on this year.
In order to survive, primitive humans who migrated to a new place forced their bodies to change their original genes, and the modified genes were passed down from generation to generation, and this is purely personal speculation.
Many people may also wonder whether people of different skin colors in the world belong to the same ancestor? Although the current historiography circles speculate that they are the same ancestor, there is no evidence to support this statement. So it's hard to come to a conclusion, after all, it's very old, and it's not practical to really want to find Adam and Eve.
Reproductive isolation has nothing to do with humans, and it will not happen to humans for a long time in the future, after all, we humans are different from those animals, which may be the benefit of biological populations not having a separate mountain.
As for the fact that all races can mate freely, as the saying goes, everything changes without departing from their origins, and even the foundation has not changed, and how can they shake the towering trees by relying on small repairs alone?
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