Dogs, as the most loyal friends to humans, have many interesting characteristics and habits.

Dogs, as the most loyal friends to humans, have many interesting characteristics and habits. Here is some knowledge about dogs:

1. The origin of dogs can be traced back to early humans domesticating gray wolves, with domestication occurring about 40,000 to 15,000 years ago.
2. Dogs are omnivores and require a diet with a significant amount of animal protein, supplemented by plant-based components, to ensure normal development and health.
3. Dogs sometimes eat grass, but not for hunger; it's for clearing their stomachs.
4. Dogs' sleeping habits reflect their ancient survival instincts; curling up not only keeps them warm but also protects vital organs.
5. A dog's sense of smell is extremely acute, more than 10,000 times more sensitive than that of humans, and they can hear sounds at a distance four times greater than humans.
6. When drinking water, dogs use their tongues to scoop water, rather than licking.
7. Dogs judge the strength of strangers based on their line of sight; a lower posture is more likely to be accepted.
8. Dogs have specific standards for body temperature; if it's higher than the standard, it may indicate a fever and requires timely medical attention.
9. A dog's urine is corrosive and can be used to mark territory.
10. A dog's ears are controlled by 18 muscles and can perform different actions independently.
11. The patterns on a dog's nose are similar to human fingerprints and serve an identifying function.
12. When defecating, dogs adjust their bodies to align with the Earth's magnetic field, facing north-south.

Please note that the above translations are provided in a straightforward manner and may not capture all the nuances of the original text.