Which came first, the chicken or the egg?

Which came first, the chicken or the egg? All walks of life have endlessly and tirelessly discussed this question. From philosophy to paleontology to life sciences.

What is the relationship between chickens and birds? Chickens, animal kingdom, chordates, vertebrates, birds. According to the ancient Greek philosopher Aristotle (384-322 BC), "there could not be the first bird egg, because there must have been a bird that could lay the first egg." Buddhism believes that all things in the world are causally related, without beginning or end, and there is no question of who comes first and who comes later. Christianity believes that "God" created birds and birds lay eggs. Philosophical thinking, that is controversial. As for cause and effect, it is also a mystery in the end.

In 2008, Canadian paleontologists announced that eggs came before chickens. They found five eggs in a nest filled with sand, which was half a meter wide and weighed 50 kilograms. Through the study of this nest and eggs, Canadian scientists said that dinosaurs first built nests similar to bird nests and laid eggs similar to bird eggs, and then dinosaurs evolved into birds (chickens are also a kind of bird), that is, eggs existed before chickens. Chickens evolved from these carnivorous dinosaurs that laid similar eggs.

So, if we follow the research ideas of biologists, why did dinosaurs lay eggs? We all know that there are two types of cells in dinosaurs, one is somatic cells, which constitute internal organs, brains, skin, etc.; the other is called germ cells, which are related to reproduction. The material that determines our inheritance in cells is DNA, which can mutate through many factors, such as physical factors, radiation, temperature, chemical carcinogens such as benzene and coal tar, and biological factors such as viruses. If these factors cause the genetic material DNA of reproductive cells to mutate, it will have a great impact on future generations. For example, the mutation of dinosaur reproductive cell DNA caused the next generation of dinosaurs to lay eggs similar to bird eggs. This kind of bird egg may have the physiological function of laying eggs after hatching. So the first bird must come from the first bird egg.

When we suddenly realized that there was an egg before the chicken, British scientists gave us another explanation. They believe that there was a chicken before the egg. In 2010, British scientists Frieden and Oldman and other researchers discovered that the structure of the egg depends on a protein found in the hen's ovary, which is called ovocledidin-17 (OC-17 for short). OC-17 protein controls the synthesis of eggs. Without OC-17 protein, the outside of the egg cannot crystallize to form an eggshell. In other words, OC-17 protein is a key factor in the formation of eggshells. But scientists have also found that OC-17 protein can only be produced in the ovaries of birds. At this time, we can't help but beat our chests and stamp our feet. What is the reason? The mystery of the ages was overturned just after it was solved?

Speaking of this, someone will definitely ask, in the end do we call the creature that lays eggs a bird or a dinosaur? So this is the crux of the problem. If the first bird egg creature is called a dinosaur, not a bird, then there must be eggs before chickens. If bird eggs can be called birds, then there must be chickens before eggs.

As we all know, biology has certain classifications, which is a way for biology to classify biological species. Modern biological taxonomy originated from Linnaeus' system, who classified species according to their common physiological characteristics. Linnaeus divided nature into three domains: plants, animals, and minerals. Under the animal and plant realms, there are four levels: class, order, genus, and species, thus establishing a hierarchical system of classification. After Linnaeus, this system was gradually improved according to Darwin's principle of common ancestry. In recent years, molecular systematics has applied bioinformatics methods to analyze genomic DNA, which is greatly changing many original classifications.

So, in my opinion, the first dinosaur that laid bird-like eggs had no different physiological characteristics from other dinosaurs, except that the eggs it laid were similar to bird eggs to a certain extent, and should be classified as a dinosaur according to biological classification. As for OC-17 protein, dinosaurs themselves lay eggs, and the shape of dinosaur eggs is similar to that of bird eggs. We can also speculate that OC-17 protein may also be produced in dinosaur ovaries, but at this time, dinosaurs are still dinosaurs. That is, the egg came first and the chicken came later.

So, do you think the chicken or the egg came first?

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