What kind of dog is the wild Tibetan mastiff, and how are they domesticated?

This is the smallest pet dog breed in the world, known as Chihuahuas, they are as small as 15cm and weigh only 1-3kg.

Here's what a Chihuahua looks like when it's standing next to a large dog:

These two pet dogs are very different in size, appearance, or other characteristics. If they are placed in the wild, it may be difficult for us to associate the relationship between them.

However, biologically these two pet dogs belong to the same species, both domestic dogs, and they are related just like we humans have different skin tones.

Not only these two pet dogs, but in fact more than 400 pet dog breeds in the world are domestic dogs, and even though they have significant differences in appearance, they are biologically the same.

The Tibetan Mastiff is also a kind of domestic dog, and all domestic dogs are domesticated animals, so there is no such thing as a wild Tibetan Mastiff in the world, and there are only "stray Tibetan Mastiffs".

Why are domestic dogs so diverse?

Domestic dogs are the earliest animals domesticated by humans. Although the specific domestication time cannot be verified, it is certain that they were domesticated before humans developed agriculture (the specific time is about 23,000 to 15,000 years ago.) Before), and all other domestic animals were domesticated after the development of agriculture. From this point of view, domestic dogs and humans have an absolutely close relationship.

Through DNA research, all domestic dogs are now domesticated from an extinct wild wolf - we can call it the wild ancestor of the domestic dog. In terms of taxonomy, it is the closest to the gray wolf that still exists today. blood relation.

The domestication of domestic dogs only happened once in a certain area, and then with the migration of humans, domestic dogs were distributed all over the world, but it is impossible to verify where the domestic dogs were domesticated. The most likely one is Siberia. .

There is actually a lot of controversy about why humans domesticated wolves.

One explanation is that humans domesticated wolves to assist themselves in hunting; another explanation is that wolves have been eating food discarded by humans and gradually integrated into human society. This hypothesis is that wolves chose us, so there is no purpose for human domestication. .

No matter how wolves entered human society, it is certain that in the next ten thousand or two thousand years, human beings have "transformed" wolves in a variety of ways according to their own survival and aesthetic needs.

The "transformation" method is selective breeding. While the ancients didn't know the secrets of genes, they probably knew better than we do now how to breed.

For example, when the ancients needed a larger domestic dog, they kept looking for bigger dogs to manually intervene in their breeding.

Over time, the gene expression of "big" is continuously enhanced, resulting in a large dog breed that is completely different in size from other domestic dog breeds.

Now all the characteristics of the Tibetan Mastiff are obtained by human selective breeding step by step.

Tibetan Mastiff Cultivation

Tibetan Mastiffs are very old dog breeds, they may have lived with humans for 6,000 years in the high altitudes of the Himalayas and Qinghai-Tibet Plateau.

At first, it may be to protect people in the plateau area from animals such as bears, wolves and snow leopards. Later, it was more to protect Tibetan Buddhist monasteries and monks, as well as herdsmen's flocks, so many Tibetan mastiffs are kept in the daytime. In the cage and released at night, this living habit makes them extremely ferocious.

Tibetan mastiffs are different from other domestic dog breeds. One of the most typical features is that they have higher levels of hemoglobin (the protein that transports oxygen), which is the key to their adaptation to the hypoxic environment at high altitudes.

Researchers have long wondered why Tibetan mastiffs have such characteristics, while other dog breeds do not.

Some studies have found that this is because Tibetan mastiffs possess hypoxia-inducible factor 2α (EPAS1), which is very active in hypoxic environments and is the key to the ability of mammals to live on the plateau. allele.

At first, humans brought domestic dogs to Tibet, but they completed crossbreeding with animals that had adapted to highland life in the wild, and finally obtained this gene, which humans retained in subsequent selective breeding.

However, it is still unclear what kind of wild animal it is, so now scientists have named it the "ghost population", only knowing that it should be a wolf-like canid that is very different from modern Arctic wolves and domestic dogs.

With this adaptive trait, the Tibetan Mastiff was continuously selectively bred for thousands of years, and finally became today's Tibetan Mastiff.

Finally: the sadness of purebred dogs!

Purebred dogs like the Tibetan Mastiff actually just look healthy. They have many diseases. The most common disease for Tibetan Mastiffs is Canine Inherited Demyelinating Disease (CIDN).

Others also include a series of problems such as short lifespan, hypothyroidism, missing teeth, and malocclusion.

Many genetic diseases follow selective breeding, which, like the body types we mentioned earlier, is constantly enhanced.

In fact, not only Tibetan mastiffs, but all purebred dogs in the world have these problems, and all of them are basically created by humans to meet their own aesthetic needs.