We’ve all heard of hybridization, but have you heard of backcrossing? This is a special artificial breeding method used to select a certain trait of organisms. Backcrossing is widely used in the cultivation of plants and pet breeds. Although this method has been with humans for a

crosses, but have you heard of backcrosses and ?

This is a special artificial breeding method, used to select a certain trait of organisms.

Backcrossing is widely used in the cultivation of plants and pet breeds. Although this method has been with humans for a long time, it is very controversial.

Let us take a look today, why do we need to backcross animals? And what are its advantages and disadvantages.

Human-bred sheep

What is backcrossing? To a certain extent,

backcrossing is a kind of inbreeding . It is to find parents with certain traits and let them mate to obtain offspring.

then mate the parents with the first-generation offspring to obtain the second generation, and then mate the parents with the second-generation offspring to obtain the third generation.

continues endlessly until produces descendants with stable traits .

From a human perspective, this is a very, very moral and ethical challenge!

is the inbreeding of inbreeding, and is the direct blood relative of !

Genealogy chart of backcrossing

This technology is very common in the breeding of pet dogs. For example, the common pet dogs in our lives are actually obtained through backcrossing.

Did you know that the genetic similarity between our pet dogs and wolves is 99%.

can be like this, saying that pet dogs are biologically a subspecies of gray wolves .

But dogs and wolves obviously look different, so why are they so closely related biologically?

Because of the breeding of pet dogs, the essence is actually the stable appearance of gray wolves with certain traits obtained through constant backcrossing.

Wolves and dogs

These traits are not necessarily good . For example, we often dislike some small pet dogs Teddy . People also gave it a nickname "Tai Ri Tian" because Teddy always It will perform some indescribable actions on surrounding objects.

and Chihuahua always bark at people, which makes people feel disgusted.

Zoologists say that the reason why such small dogs like to bark is because their heads are too small and their brains are constantly compressing their brains.

To put it bluntly, it is a bit neurotic !

Chihuahuas have mixed reputations

So why do small dogs have such problems?

Zoologists say that people can actually think of small dogs as wolves suffering from dwarfism , then everything will be explained.

It is a kind of sick wolf. When it is sick, it will naturally feel uncomfortable, so it will make some actions that look very annoying.

So how do you get this small dog? First, select the smaller dog as the parent . After they breed the first generation, let it mate with the first generation, and select the smallest dog among them to mate with the parent.

Small pet dogs

After getting the second generation, they select the smallest ones and mate with the parents. As the accumulation of each generation, becomes smaller and smaller .

The most frightening size among pet dogs is teacup dog , that is, a dog can be put into a cup, and the dog is already an adult!

Although this looks very cute, the life of a teacup dog is very painful.

is actually not just pet dogs, pet cats are also obtained in this way, including those top horse racing on the field. Their birth is also inseparable from backcrossing. It can be said that human life is inseparable from backcrossing technology.

Deformed and Aesthetic Teacup Dogs

The Controversy of Backcrossing

However, the backcrossing technology has also been opposed by many people. The reason is that this kind of artificial inbreeding has brought very painful consequences to the organism itself.

For example, we mentioned earlier the problem of small dogs being emotionally unstable , and such backcrossing will cause the accumulation of disease-causing genes, which will cause offspring to suffer from malignant tumors , which is what we call cancer .

The more typical one is Bernese Mountain Dog . Because the gene pool is very small, almost every Bernese Mountain Dog will get cancer, so the average life span is very short, only about 7 years.

In addition, the folded-eared cat , which is very popular among pet cats, is also a breed obtained through continuous backcrossing.

There are many diseases in Bernese Mountain Dogs

, but Fold-eared cats suffer from very serious joint diseases. No Fold-eared cat walks calmly, and almost all of them finish their birth in pain.

The tragedies of these pets have made humans reflect, can avoid some backcrossing of ? The biggest danger of

backcrossing is that it is inbreeding, and it is also inbreeding between direct blood relatives, which will combine beneficial genes. For example, some pet dogs are larger than wolves .

But at the same time, many disease-causing genes will be "strongly combined". As a result, some pet dogs will suffer from diseases that wolves do not have at all.

A folded-eared cat will suffer throughout its life

Advantages of backcrossing

So does backcrossing really have no benefits at all?

certainly isn't. The most brilliant use of backcrossing technology is of course in agriculture . For example, do you know what a watermelon looked like more than 200 years ago?

According to the depictions in European oil paintings, htmlthe watermelon more than 1,200 years ago looked completely different from what it looks like now. It was more like the cut appearance of the current winter melon.

And the flesh of the melon is not the red it is now, it is a little pink.

Watermelons in oil paintings in the past

Botanists traced back to their roots and found the ancestor of watermelon, , which is a melon plant that grows in the desert. It is not only not sweet but also poisonous.

People's cultivation of watermelons can be traced back to Egypt more than 14,000 years ago. In other words, the watermelons we have today are the foundation of 4,000 years of continuous cultivation.

After generations of backcrossing, today's watermelons are sweet and delicious, come in many varieties, and are relatively cheap.

It can be said that without backcrossing technology, there would be no crops that humans eat today.

Therefore, in the eyes of some people, there is no need to call backcrossing a devilish or evil technology. Isn’t this just picking up the bowl to eat and putting down the bowl to curse?

Today's watermelon

Human beings have enjoyed all the benefits brought by backcrossing technology, so backcrossing cannot be completely denied. The key depends on how to use it.

Many people believe that almost all animal species related to humans are bred through backcrossing, and many of these animal species are subject to the negative impacts of backcrossing.

Therefore, the backcrossing of animals should be cancelled, and only the backcrossing of plants should be performed.

Some people have suggested that the benefits brought by the return of animals to humans are irreplaceable.

For example, the disliked Teddy and Chihuahua . Although they have many criticisms, it is undeniable that they are currently the most popular dog breeds among the elderly. Many lonely elderly people like to keep a small dog. Dogs as companions.

Old people like to keep small dogs

because the size of small dogs is not dangerous to the elderly. If it is a large dog, it is likely to drag the elderly and cause them to be injured.

Small dogs do not have this problem, and small dogs eat very little , which reduces the burden of raising pets at home.

More importantly, small dogs need to seek shelter because of their small size, which makes more dependent on their owners , which can satisfy the lonely heart of the elderly.

So this is also a benefit brought by backcrossing pet dogs, not to mention that the traits of small dogs have long been stable, and they no longer need to be obtained by backcrossing from generation to generation.

Old people need companionship

Other hybridization methods

In fact, under human intervention, abnormal reproduction between animals is not only backcrossing, but another controversial one is cross-species hybridization.

For example, our common mule is the offspring of donkey and horse .

We know that although donkeys and horses look very similar, they are two completely different species , and their chromosome numbers are different.

The mules they gave birth to suffered from infertility and were unable to bear children .

A horse and a donkey gave birth to a mule

Another example is the popular liger . It was originally thought that it could inherit the advantages of its parents and become the new generation of "king of beasts".

Who would have thought that a liger inherited the shortcomings of its parents and turned into a big-headed doll with fat head and big ears. The body proportions looked very uncoordinated and there was no domineering air at all.

However, zoos around the world are still secretly breeding ligers, because this animal is very gimmick and can bring considerable profits to the zoo. People will always rush to see the hybrid offspring of lions and tigers.

The defective liger

The offspring obtained from cross-species crosses are usually disposable products. When their lifespan is over, cannot be used again, and they must be continuously crossed to obtain them.

Moreover, humans have done a very crazy thing in history, that is, human-ape hybridization, in an attempt to use and orangutans to obtain to produce offspring.

Although this crazy experiment was eventually stopped, we can know from it how terrible it is when science loses the restraint of morality! The

backcrossing technology cannot be used on humans, so it will not violate the so-called morals and ethics of human society.

Crazy human-ape hybrid experiment

Human beings have enjoyed so many dividends from backcrossing technology, and there is no reason to devalue it as worthless.