Why does the rooster crow early in the morning?

The cock crows and the hen lays eggs. Except for a few birds such as owls and mandarin ducks, other birds can't see anything at night. So is the rooster. At night, they may be attacked at any time, so they feel very uneasy. In the morning, the rooster's eyes can see again, so he is very excited. In order to express this excitement, I began to sing excitedly. This is also the rooster's instinctive response to light stimulation. After a long time, morning singing has become a habit of roosters. Now, even if the rooster is placed in a dark place so that it can't see the light, it will still crow in the morning. Supplement: Because there is a "biological clock" in the cock's brain. According to scientific research, between the cock's brain and cerebellum, there is an endocrine organ called pineal gland, where a "biological clock" grows. Because the pineal gland can secrete a kind of black tensin at night, the rooster can remember the law of light and shade and sing periodically. In addition, the rooster is also an extremely aggressive animal. It warns other cocks not to come to its territory by crowing, otherwise it is impolite. The rooster will crow to attract the attention of the hen and remind her that there is a handsome guy here, but don't go anywhere else. In a word, rooster crows have many different meanings, so the way of crowing is also very different. Supplement: Scientists have announced that the answer to this puzzle is that there are eggs before chickens. The dispute between chicken and egg has a long history. The question of which came first, the chicken or the egg, was finally solved. After studying the dinosaur eggs 77 million years ago, scientists announced that the answer to this puzzle was that there were eggs before chickens. 77 million years ago, when the sea level rose, the mother of a small carnivorous dinosaur had to leave her unborn baby and run for her life alone. 77 million years later, paleontologists found five incomplete eggs in a nest full of sand. This nest is half a meter wide and weighs 50 kilograms, which is equivalent to the weight of a person. Fran? ois, director of the dinosaur museum at the Royal tyrael Museum in Alberta, said: "This bird's nest has some characteristics similar to birds. Through in-depth analysis and research on these characteristics, it will help us to reveal this ancient unsolved problem, which came first, chicken or egg? " The answer to the dispute between chicken and egg is whether the egg comes first or the chicken comes first, which has always been a hot topic of debate. Recently, Dara Zelensky, a paleontologist at the University of Calgary, Alberta, said that after studying dinosaur eggs 77 million years ago, the clear answer to the puzzle surfaced: dinosaurs first built nests similar to bird's nests and laid eggs similar to birds' eggs, and then dinosaurs evolved into birds (chickens are also a kind of birds), which is clear that eggs existed before chickens. Chickens evolved from these egg-like carnivorous dinosaurs. The bird's nest found in North America provides the strongest evidence that eggs that look like birds or chickens appeared before chickens. Therefore, the original puzzle can now be rewritten as: Which came first, the dinosaur or the egg? Follow-up: Wow, who said that?