Review
The Chinese literary masterpiece "Dream of the Red Chamber" tells the story of the rise and fall of a family, among which the love and hatred of Jia Baoyu, Lin Daiyu and Xue Baochao have touched the hearts of viewers.
However, from the perspective of modern biology, Jia Baoyu is a tragedy whether he is with Lin Daiyu or With Xue Baochao, and the tragedy here does not refer to love, but to the genes of their descendants.
Jia Baoyu's father and Lin Daiyu's mother are brothers and sisters, Jia Baoyu's mother and Xue Baochao's mother are sisters, from the perspective of modern law, Baoyu Daiyu and Baoyu Baochao are counted as collateral blood relatives within three generations.
"Dream of the Red Chamber" Lin Daiyu and Jia Baoyu stills
According to the newly enacted Civil Code, they cannot marry. Of course, the story of the Dream of the Red Chamber took place in ancient times, when there was no current ethical concept, but in order to safeguard the interests and status of the family, it was very much advocated for the marriage of close relatives.
However, the so-called kissing and kissing, but this "kiss" does not include all relatives. In ancient times, it was a patriarchal-dominated society, and women in the family were not recorded in the family tree, and they were no longer counted as their own families after marriage.
Therefore, for relatives with different surnames, intermarriage is not prohibited, such as Baoyu and Daiyu mentioned above, Daiyu's mother does not belong to Jia Fu after marriage, so Daiyu is considered an outsider. Conversely, two people who are not related by blood may not be able to intermarry between the same surname in ancient times because the same surname is considered to be from the same family.
"Dream of the Red Chamber" Lin Daiyu and Jia Baoyu stills
inbreeding
Human law defines direct blood relatives and collateral blood relatives within three generations as close relatives, and almost every country has a clear rule that such persons are not allowed to marry. This is not necessarily to beat the Mandarin duck, but for health reasons, because past history tells us that the disadvantages of marriage between close relatives.
The most famous case of inbreeding in history is the Habsburg family, the most powerful and widely ruled royal family in European history, ruling the Holy Roman Empire, the Spanish Empire, the Grand Duchy of Austria, the Austrian Empire, and the Austro-Hungarian Empire.
The Habsburgs lasted from the sixth century to the beginning of the eighteenth century, and the history of the family was 1,000 years long, but its demise is strange.
Habsburgs related drawings
The last direct ruler of the Habsburg dynasty was Carlos II, who was short and strange in stature, with a chin that looked like a shoehorn, could only speak at the age of 4 and could walk at the age of 8, and often convulsed when he became an adult, and then lost the ability to walk.
He died at the age of 39 and was unable to leave any descendants, and the Habsburg dynasty lost its immediate heirs and was instead inherited by members of the collateral family, after which it collapsed.
People at the time did not know that Carlos II was suffering from a genetic disease and said that he was cursed. Later studies by biologists have shown that Carlos II suffered from at least two diseases caused by the marriage of close relatives.
Portrait of Carlos II
One is insufficient pituitary gland secretion, the other is kidney disease, and his strange shoehorn chin is also married by close relatives. It turned out that in the 200 years before Carlos II, the Habsburg family had 9 close relatives married.
These include two uncles and nieces, and two cousins within one generation. This combination was due to the ancient European pursuit of purity of blood, and the Habsburgs thought that in this way they would always have power in their own hands and not fall into the hands of others.
We modern people will wonder, human beings are so smart, is it not enough time to find problems with the offspring born of such a combination? Of course, it can be found that not only people, but even animals have found the harm of recent breeding, and the reason for not giving up is that the polarization of inbreeding is polarized.
Portrait of Carlos II
Advantages and disadvantages of inbreeding
Inbreeding is simply a diode, not that it emits light, but its advantages and disadvantages are polarized, the advantages are obvious, and the disadvantages are also obvious.
Inbreeding will make the probability of the two poles superimposed, that is, the probability of advantages increases and the probability of disadvantages also increases, this time is the time to rely on luck.
The ancients generally gave birth to more children, even if the close relatives married and gave birth to the offspring with accumulated shortcomings, the medical underdevelopment they could not live long and were eliminated, and the offspring of those accumulated advantages would achieve better development and continue the glory of the family.
The ancients were not as stupid as we think, and the reason they chose to marry close relatives was to increase the number of excellent offspring obtained by the compendium, and as for the failed offspring, they were either naturally eliminated or artificially eliminated.
Genetic selection theme map
The previous people, especially the nobles and royals, had long discovered this law, so they preferred to risk giving birth to sick children and marry close relatives, the purpose of which was to select excellent descendants to inherit the family's property and maintain the stability of the family.
It is only naturally fair, such an accumulation is bound to have a limit, it will not start the button because of the status of nobles or commoners, no matter how hard the family, in the end, it will inevitably fall into destruction.
With the rise of the human thought movement, people felt that such practices were becoming more and more inhumane, and people began to try to avoid the production of sick offspring from the source, and after years of revision and progress, there was what we called a law prohibiting the marriage of close relatives. But this law only applies to humans and does not apply to animals.
Ancient nobles and royalty would marry close relatives to ensure that the offspring were genetically good
backcross
After the 18th century, European aristocrats consciously avoided the marriage of close relatives, and even if there were relationships, they were no longer as crazy as before, but the pure heart of the comparison blood would not be extinguished.
They began to satisfy this heart-wrenching hobby in some animals. The one who suffered the most from the European nobility was the dog. In the 19th century, Europe had entered an industrial civilization, and the nascent aristocrats of capital were ridiculed by the old aristocrats.
The reason was that they did not have noble blood, so these new nobles began to make a big fuss about the blood of dogs. Ancient dog breeds have a characteristic, in terms of body size closer to their ancestors, the wolf, and their functions are more inclined to hunting.
Portrait of European nobility
It is also inevitable that there will be pygmy dogs in dogs, and these small sized sick dogs are very popular with the nobility, so they let the sick dog mate with other dogs as the first generation, the sub-generation continues to mate with the sick dog, and the second generation also mates with it.
Generation after generation of this, and finally get a more stable pygmy dog, this kind of dog can be held in the arms, deeply loved by the noblewomen. This inbreeding between offspring and one's own parents is called backcrossing.
Dog dealers saw the benefits in the middle, so more dog breeds were born, and since small dogs could be obtained, they could also get large dogs. Select the "gigantism" disease in dogs, take the method of backcrossing, and get dogs that are far larger than the size of wolves, such as Great Dane and Newfoundland.
There will also be small short legs in the dog, so let this short leg be the parent, and constantly rebreed with the offspring, and get the current short-legged dog, such as corgi and dachshund. There will also be variations of golden hair in dogs, so let them return to the golden retrievers that are now popular all over the world, and so on.
Dogs are in a sense the offspring of wolves
Nowadays, dogs and wolves are not separated in biological biology, there is no reproductive isolation between them, but the appearance has been 108,000 miles apart, in layman's terms, the dogs raised by humans now are all sick wolves, and they are not seriously treated.
For example, chihuahuas suffer from mental illness, so it likes to call, and there are also blue-eyed huskies with mental illness. Great Danes are susceptible to joint diseases because they are too large, and they live for less than 8 years.
Mount Bern lives less than 10 years because of the presence of oncogenes. Pit bulls can suffocate in their sleep due to shortened snouts due to shortened snouts.
Labrador loses the gene in his body that senses fullness and becomes non-stop eating, eventually becoming obese or dying. These dogs, bred by the special hobbies of human beings, end up living in this world in a painful way.
Sick Chihuahua
Advantages and disadvantages of backhand
Backcrossing is also a type of inbreeding, so it has all the advantages and disadvantages of inbreeding. The advantage is obvious, that is, it will make the parent's traits more stable, such as the dog's pocket size and small short legs.
If the traits of the first generation of parents are only accidental genetic mutations, then the traits presented after backcrossing become inevitable, which is a human choice.
For some rare and protected animals, backcrossing is a means of saving them. For example, the sultan, the world's last northern white rhino, was prepared to use backcrossing to mate with one of his female offspring to preserve the genes of the northern white rhino, but unfortunately the sultan was too old to succeed.
Of course, there are also successful examples, such as the endangered Wood cycad, which was found to have only one male plant left, and later allowed it to cross with the more related Nettal cycad, which continued in the way wood cycads were rebred with hybrid offspring.
White Rhino Sultan
The advantages of backcrossing are played to the extreme in agriculture and animal husbandry, and the fruits we eat with excellent taste are obtained through the way of backcrossing, and the Holstein dairy cows with high milk production are also obtained in this way.
It is no exaggeration to say that except for people who are not allowed to participate because of the law, other animals and plants can participate in the return. However, nature opened a window for the return and closed a door for it.
Backcrossing allows the parental shape to be stable and inherited, but also increases the probability of parental shortcomings, and finally these pathologies begin to stabilize. For example, the knee problem of a giant dog.
The more times you return, the harder it is to avoid, and eventually it becomes the standard for this breed of dog. And the backhaul will make the gene exchange area narrower, resulting in genetic diversity is not prominent, so that the offspring obtained can only live in the environment built by humans for a lifetime, and once they enter the natural environment, they will be eliminated.
Holstein cows have also undergone back-inmates
Conflict of ideas
Dogs obtained by means of inbreeding such as backbringing are full of all kinds of problems, which can't help but make people discuss, is it really good to toss animals like this?
Humans forbid close relatives to marry, so why do these animals keep making love? Isn't it ethical to get unhealthy offspring?
The problem is complex, first of all, there is no so-called ethics for animals, humans have laws that do not allow close relatives to marry, and humans consciously avoid it.
Human beings have laws that do not allow close relatives to marry
Animals can't tell the other person's relationship with their own relatives, how can they notice the problem of inbreeding during estrus? Lions, for example, will be driven out of the lion group when the male lion reaches adulthood.
Zoologists at first thought that this was a mechanism for lions to prevent close relatives from marrying, but later found that this was probably just a practice of the lion king to consolidate his position.
Because the lioness does not go, that is to say, the male lion will have backbreavals with her daughter to some extent, even without human intervention in the natural state.
Lions on the prairie
Second, although the animals obtained from inbreeding are more or less faulty, humans have never put these diseased offspring into nature.
They live in the human world, eating is given by people, using what people give, sick people are healed, they are the species created by man, they can't live at all without people.
So humans allowing them to multiply in their own environment does not violate any laws of nature. Finally, under the premise that cloning technology is not yet mature, backcrossing is the only way to continue endangered species, it is not a flood beast for organisms, it has its own significance.
Backcrossing can perpetuate endangered species (white-bellied golden pheasant)
epilogue
Inbreeding is a double-edged sword, it can make the advantages more optimized, but also can make the shortcomings worse, this probability is like opening a blind box, no one can say what the final result is, people can not at least not take life as a bet to bet on the consequences of inbreeding, whether from a humanitarian or scientific point of view.
But animals are different from us, they have no concept of close relatives, so there is no ethics, even if humans do not participate, after entering the estrus period, they may naturally have backcrossing, humans just let them backoff in a certain direction.
In fact, this is a very neutral thing, not how good it is, not very bad, it may depend on the degree of benefit of human beings in this matter, if the meaning is very large, then this is good, if the meaning is small or even no, then this is not good.
Backcrossing has brought many new varieties to mankind and enriched the spiritual world and stomach world of mankind, so it is a feasible thing to do at present.
Canine backcrossing has a more or lesser effect on dogs