Horses and donkeys crossed to give birth to mules. Mules are male and female, sexually sound, have sperm eggs, can mate, why can't they have children? With horses and donkeys, why did the ancients breed mules?
Today we will talk about the special case of subverting biological common sense, but the mule of the same species cannot reproduce.
<h1 class= "pgc-h-arrow-right" > mules are the offspring of horses and donkey hybrids</h1>
Reproduction is the noble mission of the continuation of species, and all life in nature is working for it, including us humans. Originally horses and donkeys, well water does not violate the river water, one galloping on the battlefield, achieving the glorious dream of Genghis Khan in the era of cold weapons, and one working hard at home, silently sprinkling countless sweats for the old peasants to survive.
In traditional farming societies, agricultural production is the most important thing. Even if there is a war, the soldiers and horses have not moved, and the grain and grass have gone first. On the battlefield, donkeys are not as good as horses, but in farmers, horses are inferior to donkeys. As a result, the two were combined, and the mule that was born, out of blue, was better than blue, and became the favorite servitude of the working people.
Therefore, there is a folk saying: copper donkey iron mule, paper paste horse.
Legend has it that as early as the Spring and Autumn Period, someone bred donkeys and horses and gave birth to strange mules. In the eyes of the people at that time, this was a treasure, just like the lion and tiger beast that were crossed and bred, and placed in the palace for people to see. Mules really multiplied in large numbers and existed as the main household servant animals until the Ming Dynasty. Since then, the obedient, well-bred and capable mule has become the favorite of the working people and has been used to this day. In the mountainous countryside, there are still a large number of mules in existence.
Mules are divided into two types.
One is called the horse mule, which is the offspring of a male donkey and a mare hybrid, large, looks like a horse, barks like a donkey, has a large and long-lasting pull, and is suitable for pulling carts and packs.
The other is called the donkey mule, which is the offspring of a cross of stallions and female donkeys, small, looks like a donkey, has the flexibility of a horse, and is good at running.
In general, mules are larger than donkeys and stronger than horses, and are not considered independent species. Compared with donkey mules, horse mules are more powerful, more useful, and more popular with working people.
<h1 class= "pgc-h-arrow-right" > second, why breed mules? </h1>
Since mules cannot reproduce and have a service life of only twenty or thirty years, why breed this animal? What are the advantages of mules?
Hybridization is a very important subject in biology, the purpose of which is to preserve the advantages of the patrilineal and matrilineal lines, reduce their shortcomings, and make the offspring better than the blue out of the blue.
Mules exist to preserve the virtues of horses and donkeys. Horses and donkeys both belong to the genus Equine, the DNA is highly similar, and the mules produced after hybridization have a "hybrid advantage", which are superior to their parents in terms of adaptability, strength and disease resistance, and even in feeding, they are much simpler and rougher. These advantages were exactly what the working people of ancient times desperately needed, so the mule became one of the most important species of servitude.
Mules make a great contribution to the survival and development of human beings. Even today, in some remote mountainous areas, mules are still an important labor force for families. The main reason why humans breed and breed mules is because mules have four major advantages.
First of all, in terms of agricultural and civilian performance, mules are stronger than horses.
Secondly, mules are particularly resistant to roughage and have lower feeding costs.
Third, mules are thick and honest, hard-working, obedient and obedient.
Fourth, mules have a strong physique, strong disease resistance and adaptability.
Of course, mules are not without their drawbacks. One of the most critical and prominent points is the extremely poor reproductive ability. As a service animal, mules serve for up to twenty or thirty years. So, even if it can't procreate, people are still nurturing from generation to generation.
<h1 class="pgc-h-arrow-right" >3. Why can't mules have children? </h1>
Mules are male and female, sexually sound, have sperm, and eggs can mate, but why can't they have children?
If you want to blame, you can only blame the mule's parents, the horse and the donkey. The reason mules are not reproductive is because the chromosomes are not paired. Horses have 64 chromosomes, while donkeys have only 62 chromosomes. The mules that were born when the two were combined, the chromosomes became 63, and the germ cells could not perform normal meiosis.
Why do germ cells perform meiosis?
Because in the process of sexual reproduction, both male and female need to give half of their genes to the next generation. Thus, theoretically, only animals with even-numbered chromosomes can reproduce, and odd chromosomes have never meant inability to reproduce.
Mules have only 63 chromosomes and cannot be divided into 31.5 pairs. As a result, both the male mule and most female mules are incapable of reproduction.
But the magic of the biological world is to create miracles.
Exceptions have been made to theoretically impossible things. A very small number of mules also produce offspring. In 1988, there was a case in Henan, China. A female mule and another male donkey crossed and gave birth to offspring.
Such examples do not only exist in China, but also abroad. The British BBC News has reported that such a thing also occurred in Morocco in 1884. According to the statistics recorded, no less than 60 cases of mules giving birth to offspring have been reported.
This strange phenomenon is very difficult for biologists to understand. After a lot of scientific research, it is still impossible to explain according to the theoretical basis of reproductive isolation in biological genetics. In the end, it can only be attributed to the greatness and mystery of life, and it is necessary to continue to work hard to find the ultimate meaning of life.
Finally, let's answer this question. Mules are not absolutely infertile, but their reproductive ability is extremely poor, and hundreds of billions of efforts are possible in exchange for the results of a flowering.
The so-called ruler is shorter and the inch is longer. Humans, who value the endurance of a mule, have to bear the fact that it is difficult to procreate. What do you think about that? Welcome to leave a message to discuss.