Chapter 26 She said: So nervous!

I said, "By pure coincidence, a female sparrow appeared. Hereditary interest in the darker males, and only the darker counterparts, kept the white birds aside. Every time the eggs hatched Come out, the father of the baby is always the darker male bird. Compared with other male birds, the father bird bird has more black feathers. If the children in the egg did not promote the genetic combination, history would not be rewritten. " She said, "Ha, you're still talking about sex." I said, "What I'm trying to say is that it's important that those children inherit two traits from their parents, one is black plumage, and the other is a tendency to love that black plumage. , the genes carrying these two traits—that is, the gene for male birds to have black feathers and the gene for female birds to like black birds—combine together and have a chance to be passed on. This accidental change from the mother of the chick is obtained In order to spread, the result is that all the chicks go to the blackbird, and all the chicks have darker plumage. The offspring will continue to reproduce, passing these two combined genes to the grandchildren of the female bird , and the grandchildren will carry on.”

"The result is that the characteristics of the first mother bird spread out until ... until what?" she said. I said, "Until it became commonplace to gravitate to black-feathered males, the ignorance of them by females was quietly weeded out by evolution." She said: "It's interesting, but I'm a bit behind. Don't females who don't like black males breed?" I said, "That's right, but they are gradually driven out, generation by generation, by females who prefer black males. The combination of the latter genes, blackbirds and blackbirds, occurs by targeted selection, namely The selection was made against males with black plumage, so the odds of success were higher."

You can think of this as a preference that both males and females seek each other out.Birds that don't have black feathers or don't like blackbirds breed at will, without targeting. They are punished after a long time, and they are scared away by another kind of the same kind. She said: "I still haven't been able to fully follow, but the main line is clear, and I also understand why this is related to sexual selection. It is the motivation of choosing an object that makes sexual selection possible. It is those female birds that separate the male birds' Pushed 'to black, it has nothing to do with climate, food or anything. Sorry, I thought you were kind of disgusting because of the sex scenes, but it's a beautiful story with a beautiful ending, Still, it puzzled me at first. Why would the unexpected female prefer the black-feathered male? You say chance, but the chances of choice are so great, if another female prefers green I am interested in feathers, and I have a leg that likes red, wouldn't there be many similar situations?"

I said, "It's very important that you point out that biology has been based on it for a long time. There's a big difference between black feathers and green feathers and red legs, and that's that the black color indicates male blood. The content of testosterone in the male sparrow. The more male sparrows produce this male hormone, the stronger they are, and the easier it is to win the competition with other male birds. In other words, the more food they can win, so that it can be more Pass on your genes to your children well. Darker feathers here mean stronger, healthier, and better fathers. The green feathers you mentioned have nothing to do with good genes, and it has nothing to do with sparrows Nothing to do, so the chances of winning the game are less."

She said: "I probably understand. But don't blame me for talking too much, we started talking about that in the process of evolution, the black skin of humans disappeared and turned white, which is the opposite direction from your sparrows." I said, "The principle is the same. In some places in our ancestors there also happened to be a preference for people with less pigment in choosing a mate. Allow me to say it again, This is also unexpected. It is also important to note that this preference is genetically determined. If this is not the case, then the emergence of white races may be related to some cultural phenomenon, that is, trends, and trends are changing every year. It may change. So, that preference has been baked into the genes. Because evolution takes a long time, the appearance of Caucasians may still come true. People at our latitude, generation after generation, Develops a preference for people with less melanin in their skin. In Africa, because of the hot sun, this preference doesn't 'live', but here it does. It may happen that the above doesn't happen, and in that case, you and My skin is all black."

"Is this something to do with hormones?" she asked. I said, "(I took the hat off my head and put it on my chest in my imagination) Science doesn't allow me to lie, so I'm going to put a question mark after this question you asked. People choose white people to have Is there a benefit? What is the benefit? What we can guess is that people with less melanin make more vitamin D, which means they are healthier. As I said before, this is a small effect, but In the considerable amount of time it takes for evolution to change things, this small effect can still create something. So white skin means healthier body, and the preference for white people has spread in our area. Turns out, it took thousands of years for our ancestors to become white. However, evidence is needed to identify this health factor, and hopefully it will emerge in the future.”

"Does this apply to other differences between races as well?" she said. I said, "Yes, the shape of the face, the color and structure of the hair, the size of the body, and so on. All of these can change if sexual selection occurs in the population. When variants are associated with genes or health, The probability of change increases." In this way, we can explain the following phenomena: for example, white people usually do not have fine curly hair; Asians have straight hair and squinted eyes.Similar examples abound. She said: "Does the human race really exist? Aren't human beings essentially the same?"

I said, "Of course there is a human race, although many people say it doesn't exist nowadays. Genetically, there is not much difference between human races, but then again, to be a human race, there is a difference between genes." The difference is not a requirement, it has more to do with your understanding of race. In fact, there should be differences in human appearance and genetics, and this is also true. Black skin color, nose shape, curly hair, there are Different from white people, these are written in genes. But between a group of white people or black people, the genetic level of difference is much smaller, so some people say that race does not exist. Anyway, distinguish people into different categories It’s really meaningless, and it will lead to discrimination. Speaking of this, we can go back to Darwin’s point of view. For him, sexual selection shows that people in the world have only formed one species, and everyone is equal. He thought that was the core argument against slavery. Of course he was right."

That brave lady has started her train of words again, and it looks like I'm talking too much.She repeated my story, and occasionally offered her own opinion.Her family got involved too, and the whole family started a discussion, full of chatter.Finally, I got off ahead of them.