do you know?All humans on the earth are the same race, but because they live in different environments, different skin tone and appearance characteristics have gradually formed.This is like cats of the same variety, and there are different hair colors and patterns.Therefore, no matter whether it is yellow, white or black, they can mate and give birth freely between them without any reproductive isolation.Does this surprise you?
In fact, this question has a clear answer in the scientific community.By comparing the DNA between different races, it is found that the similarity between them is as high as 99.9%, which is basically no difference.This shows that they all have a common ancestor, that is, the Chile, is a group of primitive humans living on the African continent.About 60,000 years ago, some Chileans began to migrate outward and gradually distributed to Asia, Europe, America and other regions.In the process, they encountered various natural environment and climatic conditions. In order to better adapt and survive, some of their genes also changed slightly.For example, in places with strong ultraviolet radiation, human skin will produce more melanin to protect themselves, so it will become darker; in the cold and dark places, human skin will reduce the secretion of melanin, so it will change to changeIt is even whiter.Although these changes affect the appearance of human beings, they have not changed their essence, and they are still the same species.
So, why can’t you mate and give birth between different species?This is because there is reproductive isolation between them, which is a common phenomenon in nature that can prevent hybrid offspring between different species.There are many forms and reasons for reproductive isolation, such as::
Geographical isolation: It refers to the unable to contact and mate with different species due to geographical obstacles, such as mountains, rivers, and oceans.For example, polar bears and penguins are unable to meet each other because they live in the north and south poles respectively.Ecological isolation: It refers to unable to mate with different species due to different living habits or habitats, such as food sex, activity time, and breeding season.For example, it is difficult to meet at night owls and daily sparrows.Physiological isolation: It refers to the unable to mate or fertilize due to the incompatibility of the anatomical structure or physiological functions between different species, such as reproductive organs, sperm or eggs.For example, ants and elephants cannot be physically matched at all.Behavioral isolation: It refers to unable to mate due to behavior differences between different species, such as puppet signals, mating rituals, and field awareness.For example, some varieties in birds attract the opposite sex through singing or showing feathers.Rear isolation: Even if different species can be matched and fertilized, the offspring generated by the generation must not survive or cannot reproduce, such as no hybrids or infertility.For example, the mule produced by donkeys and horses cannot have children.
So, why are there no reproductive isolation between different races?This is because the geographical isolation time between them is not long enough and does not reach the degree of reproductive isolation.Generally speaking, if you want to produce reproductive isolation, it takes at least hundreds of thousands of years or even millions of years to make genes sufficiently and differentiated.The migration of humans from Africa to the world is only about 60,000 years, and this time is far from enough.Moreover, in this process, humans have not completely cut off contact, but have maintained a certain degree of genetic communication.Therefore, no obvious reproductive isolation is formed between different races.
Of course, this does not mean that there is no possibility of reproductive isolation at all.In fact, there are some individual situations in human society, leading to some physiological isolation between people.For example, some couples are unable to get pregnant together, but they can change another partner.This may be because the sperm or eggs between them have some kind of immune response or exclusion, which causes fertilization or failure.For another example, although some husbands and wives can get pregnant, the fetus will cause hemolysis or other congenital diseases.This may be because the blood type or other genes between them have some incompatibility or conflict, causing abnormal or death of the fetus.Although these situations are rare, it can also be regarded as a "reproductive isolation" between humans.
In addition to physiological isolation, some people have various views and conjectures about mixed -race descendants between different races.Some people think that mixed offspring will be better, more beautiful, and smarter; some people think that mixed -race offspring will be worse, ugly, and stupid.What kind of statement is correct?
In fact, the advantages and disadvantages of mixed descendants do not have a certain answer, because it depends on what the genes they inherit are like.When the two different races are matched, their respective genes will be reorganized and randomly distributed to produce a new genome.If the descendants of the mixed race exactly inherit the excellent genes of both parents, they will show better qualities; if the mixed -race offspring just inherits the disadvantages of the parents, they will show worse characteristics.Of course, another possibility is that the mixed -race descendants inherit the average genes of both parents, then they will show the normal level.
So, what is the probability of inheriting excellent genes and disadvantages of mixed -race descendants?This is not a certain answer, because it depends on what the genes of both parents look like.Generally speaking, excellent genes and disadvantaged genes are relatively rare, so the probability of inheriting them in the mixed -race offspring is relatively low; the average gene is more common, so the probability of inheriting them in the mixed -race offspring is relatively high.Of course, this is not absolute, and sometimes there are some accidents or miracles, so that the mixed blood represents extraordinary or bad qualities.
So, will the mixed -race offspring change over time?This is not a certain answer, because it depends on the environment and society they live.Generally speaking, mixed -race descendants will be affected by the areas and culture they live in, thereby forming some adaptive changes.For example, in places with strong ultraviolet radiation, the skin of mixed -race offspring will become darker; and in a cold and dark place, the skin of mixed -race offspring will become whiter.Although these changes will not change their genes, they will affect their appearance and health.
On the other hand, mixed -race descendants are also affected by the society and culture they live, thereby forming some psychological and behavioral changes.For example, in a diversified and inclusive society, mixed -race offspring will be proud and confident; and in a single and rejection society, mixed -race offspring will feel confused and inferior.Although these changes will not change their genes, they will affect their character and life.
In short, different races can have children, and there is no reproductive isolation because they are all the same species, with common ancestors and similar genes.And different species cannot be born, and there are reproductive isolation because there are great genetic differences and isolation conditions between them.As for whether the mixed offspring is excellent or inferior, there is no certain answer, because it depends on the genes, the environment and society they inherit.
