Are everyone's dogs locked up at work?

Dogs, also known as "dogs" in Chinese, belong to Carnivora and are distributed all over the world.

Dogs, horses, cows, sheep, pigs and chickens are also called "six animals".

Some scientists believe that dogs were domesticated by early humans from gray wolves. The domestication time was from 40,000 years ago to 1.5 million years ago, and it has developed to this day. Known as "the most loyal friend of mankind", it is the pet with the highest feeding rate at present. Its life span is about ten years.

In China culture, dogs belong to one of the 12 Zodiacs, ranking 1 1 among the 12 Zodiacs.

Global quantitative editing

Dog is a very common canine mammal, and it is also the pet with the highest feeding rate.

According to United Nations statistics, there are about 600 million dogs in the world and about 200 million dogs in China. Dogs are the earliest domesticated animals.

Dominant contribution editor

Nurse dog: guarding human safety and property, guarding homes and nursing homes.

pet dog

Pet dogs (2)

Pet dog: companionship and enjoyment.

Hunting dog: hunting fee ...

Pastoral dogs: sheepdog, cattle dog. ...

Medical dogs: due to their optimistic nature, dogs are suitable for caring for and accompanying patients with mental illness, depression and autism (except violent patients); The premise is to choose a domesticated dog that won't make trouble, otherwise it may increase the burden and lead to a worse condition.

Dog care: take care of people who have difficulties in self-care and paralyzed people; Can help people take off their shoes/socks, insert cards to withdraw money, open/close doors, turn on/off lights, push/pull cars, and take things from the refrigerator.

Guide dog: Compared with guard dogs, it is more responsible to accompany its owner at all times, and most of the things of the owner really need the assistance of guide dogs; Guide the owner to cross the road, and the dog will go shopping alone.

Military dog: some countries have special military dog medals; Military dogs, police dogs, customs anti-drug dogs, airport gunpowder monitoring dogs ...

Search and rescue dogs: search and rescue when avalanches, earthquakes, fires and other disasters occur.

Traffic dogs: For example, Eskimos near the Arctic Circle and some people in northeast China use "sled dogs".

Show dogs: Most circuses have dogs specially used for performances, which have many skills and talents.

Experimental dog:

⑴ Medical experiment: In medical and pharmaceutical research, because the weight of mice is too different from that of human beings, dogs are often needed to do experiments.

Species evolution editor

Canine ancestors

Paper-cut dog photo album

Paper-cut dog photo album (20 photos)

No one knows exactly when the first interaction between man and wolf took place. Some scientists think it may be 50,000 years ago, because it took wild wolves at least so long to show today's genetic differences. At that time, humans and wolves were distributed in many places on the earth's surface, and the evolution process may have occurred in several different areas. Some scholars believe that wolves were domesticated from wild wolves to domestic animals for playing, hunting and housekeeping, that is, dogs, before 14000 years or even before 16000 years in Southeast Asia.

Dogs originated from wolves and have been recognized, but opinions vary around the specific place of birth and time. The earliest evidence of dog fossils comes from a mandible fossil in Germany 14000 years ago. These archaeological evidences support that dogs originated in southwest Asia or Europe. On the other hand, the characteristics of dog skeleton identification suggest that dogs may have originated from wolves, thus putting forward the origin theory of East Asian dogs. In addition, different breeds of dogs are very diverse in morphology, which seems to be inclined to the hypothesis that dogs originated from wolves of different geographical groups. Archaeology alone can hardly provide reliable clues about the origin of dogs. (Continued/Click: [2])

Domestication process

People and dogs live in harmony.

People and dogs live in harmony (7 photos)

Researchers at the University of Arizona in the United States unearthed two dog skulls at least 33,000 years ago from Belgium and Siberia, respectively, indicating that dogs have been tamed by humans as early as ancient times.

The researchers said that these two dogs have short noses and wide chins, while wild animals like wolves need long noses and narrow chins to catch their prey. On this basis, they think that this shows that our ancestors began to domesticate dogs long ago to resist danger and relieve loneliness. The researchers also believe that dogs may be the first animal domesticated by humans, which is much earlier than domestic animals. (Continued/Click: [3] )[4]

genetic code

Zhu Xuanxian's print "Dog"

Zhu Xuanxian's print "Dog"

The evolution of dogs is related to starch digestion: by comparing the whole genomes of dogs and wolves, researchers at Uppsala University revealed many changes in the evolution of wild dogs into human best friends. Unsurprisingly, many of these different areas affect the brain, which may explain the temperament difference between wolves and dogs. In addition, this comparative study also pointed out several areas related to digestion, including genes that help break down starch.

Researchers say that dogs may domesticate themselves by looking for humans and eating human leftovers. The study of Israeli fossils and genetics confirmed that the domestication period of dogs was about 6.5438+0 million years ago, which coincided with the agricultural revolution, and human beings changed from nomadic hunting to farming and settled life. Some scientists believe that wolves are attracted to the garbage dumps of these early settlements and feed on the leftovers of vegetables and cereal plants. (Continued/Click: [5] )[6]

Civilization influence

Loyal dog and eight male sculptures

Loyal dog and eight male sculptures

As the earliest domesticated livestock, the existence and evolution of dogs are inextricably linked with the development of human civilization. Westerners praise it with exquisite works of art and regard it as the most loyal guardian. However, the status of dogs in China has always been very low. This can be seen from the archaeological discoveries unearthed in China.

The most anticipated thing is that a large number of mammalian fossils were found in Zhoujiayoufang, Yushu County, Jilin Province, China, that is, the Late Pleistocene of Paleolithic Age, about 26,000 BC-0/000 BC. In addition to human fossils, there are also "semi-fossils" of domestic dog skulls. Although some people think it belongs to Pleistocene animal fossils, more experts think it is the remains of Holocene or modern animals. This remains of domestic dogs in the Paleolithic period can show that residents in Northeast China have begun to domesticate dogs. In other words, domestic dogs in Northeast China appeared in the late Paleolithic period, about 1 10,000 years ago. The primitive humans in Northeast China were Tunguska Mongols, so it is reasonable to think that the ancestors of Donghu, Rong, Di and Su Shen domesticated dogs, among which Rong was a famous dog-raising clan.

A batch of stamps and pictures of dogs.

A collection of stamp photos of dogs (20 photos)

It can be seen that Northeast China and Mongolia are the domestication centers of domestic dogs in the late Paleolithic and early and middle Neolithic. In addition, in Anyang, Henan Province, Cishan, Hebei Province, Banpo, Xi 'an, Dawenkou, Shandong Province, Changzhou, Jiangsu Province and other places, the skeleton fossils of domestic dogs in the late Holocene were found, and it is certain that China is one of the centers of domestic dogs.

Feature-Physiology Editor

Dog's sense of smell

Dogs' olfactory sensitivity ranks first among all animals, and blind dogs can live like normal dogs with their noses. Dogs' acute sense of smell is mainly manifested in two aspects: first, they are sensitive to smells; The second is the ability to distinguish smells. The sensitivity will vary according to the kind of taste, which is about 1200 times that of human sense of smell. The dog's nose can distinguish about 2 million different smells, and it also has high analytical ability, and it can sniff out the smell it is looking for from many mixed smells. Dogs can perceive smells at the molecular level. For example, when 1 cubic centimeter contains 9000 butyric acid molecules, dogs can smell it, while in general, there are about 268× 10.e+ 16 molecules in the air per cubic centimeter. So the concentration of butyric acid felt by dogs is 3.36× 10.e- 17. When someone dilutes sulfuric acid by one millionth, dogs can still smell it, and their olfactory sensitivity to acidic substances is tens of thousands of times higher than that of people.

According to the European Lung Disease Foundation, lung cancer is the second leading cause of death in Europe. It was found that dogs trained in olfaction could sniff out 7 1 case from the breath samples of 100 patients with lung cancer, and the discrimination accuracy of non-lung cancer samples could reach 372/400. (Continued/Click: [1 1])

Dog's hearing

Dog's ear structure

Dog's ear structure

The auditory induction can reach1.2000 Hz, which is 6 times that of human beings. The farthest listening distance is about 400 times that of human beings. Dogs are also twice as able to distinguish the direction of sound as humans, and can distinguish 32 directions. It can be distinguished that the number of times the metronome vibrates per minute is 96 or 100, 133 or 144. For human passwords and simple languages, dogs can establish conditioned reflex according to the changes of tone and syllable.

Dogs can hear 40,000 cycles. The sound collected through the big ears vibrates the eardrum through the external auditory canal, even vibrates the ossicles of the middle ear, reaches the lymph of the inner ear, and then reaches the brain through the auditory nerve. Dogs can distinguish tiny or high-frequency sounds (ultrasonic waves). The ability to judge the sound source is also very strong. When a dog hears a sound, it can see and hear all directions with its eyes because of the sympathetic action of its ears and eyes. At night, even if you sleep, you should be highly alert and can clearly distinguish the sounds within the range of 1 km. In particular, we don't need to yell at the dog. Too much sound or audio is a kind of adversity stimulus for it, which will make it feel pain, fear or panic.

Dog's vision