<h1 class="pgc-h-arrow-right" data-track="1" > review</h1>
Chinese there is a saying called "donkey lips are not right for horse mouths", which is used to describe a serious mismatch between two things. In our eyes, the difference between donkeys and horses is indeed not small, but the biology class teaches us that horses and donkeys can produce offspring after mating, that is, mules.
This makes us wonder, where are the boundaries between species that can mate? To what extent is the so-called reproductive isolation effective? For example, why did the differences between the three races of black, yellow and white not affect their mating?
<h1 class="pgc-h-arrow-right" data-track="4" > ethnic divisions and characteristics</h1>
First, let's look at the concept of race. Scientists' definition and distinction of "human race" is not achieved overnight, but has undergone a relatively long process of development.
In the 17th century, there were initial attempts at the scientific division of the human race, and the earliest published method of human division from the Roman and Greek tradition was François Bernier, which is found in the book "The New Division of the Earth Based on the Different Species or Races Inhabiting the Earth".
In his writings, humanity is divided into four ethnic groups according to regional differences, including Far Easterners, Americans, Europeans, and Saharan and Sub-Africans, a division that, while meaningful, is still rough overall.
In the 19th century, anthropology began to develop, and the publication of Darwin's On the Origin of Species caused a great response. After a period of debate, natural scientists began to give more detailed racial distinctions based on the principle of "ethnographic ideology."
For example, Blumenbach's law of five divisions divides human beings into five major races, including Mongolian races, Ethiopian races, Caucasian races, Malay races, And American races, and according to the consistency of skin color, it is referred to as brown races, white races, etc. Subsequently, the criteria for this division are gradually relaxed, and gradually become the three races we often call black, yellow and white today.
In general, the distinction between these three human races is relatively obvious. From a geographical point of view, black people are mainly distributed in tropical regions, mainly In Africa and the Americas, limited by conditions such as climate and resources, the historical black people are relatively slow in human race evolution and civilization development.
But on the other hand, the harsh living environment also allows them to exercise a very good physical fitness. According to one study, blacks had much better physical indicators than yellow and white races. Early Caucasians were mainly distributed on the European continent, and migration activities only brought part of them to today's North America after the Age of Discovery, and ethnographic studies believe that their skin color is more affected by genetic mutations than by geographical environment.
Today's yellow people are mainly concentrated in eastern Asia and the west coast of the Pacific Ocean, due to geographical separation, they have developed a civilization that is completely different from the West, although it was once the world's economic center of gravity, but it eventually failed to resist the wave of the Industrial Revolution and also experienced a period of colonial history.
<h1 class="pgc-h-arrow-right" data-track="12" > different cases of reproductive isolation</h1>
It seems that there are indeed differences between black, yellow and white races, so what exactly allows them to overcome reproductive isolation and unimpeded mating? To answer this question, we must first figure out what reproductive isolation is. There are many reasons for reproductive isolation, but it comes down to the question of kinship.
If it is very distant, then whether this kinship is direct or indirect, the end result is the same, that is, the inability to mate and produce offspring. Taking horses and donkeys as an example, although they appear to be quite different in appearance, in the hierarchical classification of the overall biological "species of the genus " Phylloscopidae " , they all belong to the mammals , the order Chithus , the equinaceae , and the horse genus , and although there is a distinction at the "species" level, the kinship is already very close.
In addition, from the objective reasons of the subdivision, there are many other situations in reproductive isolation, such as geographical isolation, seasonal isolation, behavioral isolation, hybrid sterility and so on.
So which of the three races, black, yellow and white, belongs to? In the sense of kinship, humans themselves are actually in the position of the end of the classification of species, that is to say, the kinship is very similar at the beginning, and the reason why they are distributed in the north of the South China Sea is not the original natural state, which is the result of migration for survival.
Archaeology also believes that humans have a common ancestor, that is, ancient humans in Africa. As for factors such as so-called behavioral isolation, there has been no great adjustment to this kinship, and since humans everywhere are not completely isolated, genetic exchange has always existed.
In general, the various races can still be said to be interconnected, and from a genetic point of view, the logarithm of chromosomes is always consistent, so there will be no problems in mating. The so-called skin color differences between black, white and yellow people are only a type of gene expression, which is not directly related to mating and reproduction, and is not a core factor related to heredity.
<h1 class="pgc-h-arrow-right" data-track="19" > conclusion</h1>
Therefore, regardless of the color of the human race, there is no reproductive isolation, because they have sufficiently stable kinship.
At the same time, the influence of the external environment, such as seasons, regions, cultures, etc. is not significant, so unlike some animals, reproductive isolation will occur between the same kind, which is a relatively free mating and reproduction.