Every generation of chickens cuts off two feet. Will there be legless chickens in a few years?

About what? Cut off two feet from each generation of chickens. Do some chickens still have feet? In fact, you only need to look at Ke Jiquan to know this question.

Corky was first used as a working dog for grazing cattle and horses. They can bite their heels and drive cows or horses to designated places.

However, when Keji is working, his long tail is often stepped on by cows or horses, which leads to the injury or death of dogs.

In order to avoid Keji's injury, ranchers usually fix a coil on the tail of their cubs when Keji is very young, so that the tail will automatically fall off after a few days.

However, it has been hundreds of years since the first generation of Keji was cut down, and Keji will still breed offspring with tails. The reason why Keji often has no tail is actually the result of artificial tail truncation the day after tomorrow.

In other words, it is not successful to control genes by artificially cutting off a certain trait. But biologist Lamarck says it is possible. What's going on here?

Lamarck: use it in and waste it out, and inherit it the day after tomorrow.

We always thought that the theory of evolution was put forward by Darwin. Actually, the theory of evolution existed before Darwin, including Lamarck's theory of evolution.

Lamarck believes that when living things exist, frequently used parts will evolve, such as the running speed of tigers; The parts that are not often used will degenerate. For example, most of the fish living in the deep sea are blind.

Moreover, Lamarck believes that acquired traits can be passed down from generation to generation through genes. For example, a giraffe with a short neck will involuntarily stretch its neck when eating leaves from a tree, resulting in a longer neck. And this lengthened gene will be passed on to their children, and the giraffe's neck will become so long over time.

According to Lamarck's theory, it is not difficult to see that if each generation of chickens has two feet cut off (too cruel experiment, imagine), then chickens rarely use their feet over time, and eventually the chickens born later will have no feet.

Now it seems that this theory is actually wrong, because it does not conform to the actual situation, so what is Lamarck's fault?

Law of biological evolution

According to Lamarck's theory, organisms will pass on traits that are conducive to survival to their offspring, that is to say, cheetahs with faster running speed can pass on their running speed genes to their offspring, making them run faster and faster, but actual observation shows that this is not the case.

Later, based on his observation and summary on Beagle, Darwin published his own theory of evolution, which replaced Lamarck's theory of evolution and gradually became the mainstream of society.

Darwin thought that evolution was irregular, which was just the opposite of Lamarck. Darwin believed that giraffes may have long necks or short necks when they evolved. The reason why I saw giraffes with long necks may be that there was a food crisis on the earth at that time, which caused the leaves growing in short places to lose their growth time, while giraffes with short necks starved to death because they could not eat the leaves on the trees. The long-necked giraffe survived by eating enough leaves, so the long-necked gene was eliminated and remained in the giraffe family.

This is natural selection, survival of the fittest, simply put: if the environment is suitable, then organisms will quickly breed a large number of offspring; But when it comes to food crisis, individuals who can survive successfully will be favored by natural selection, otherwise they will be eliminated.

Later, Father Mendel used pea experiments to prove the genetic law of organisms, and later generations added some things, such as neutral inheritance, so modern evolution theory is not just Darwin's theory of evolution, but a theory of evolution after advanced.

If we look at this problem with modern evolutionary theory, we can know that even if two feet are cut off in each generation of chickens, their genes will not change, so they can still give birth to offspring with feet.

If you want chickens to give birth to offspring without feet, don't cut off their feet artificially, but choose those offspring with degraded feet in each generation of chickens, and then choose from generation to generation, and you will get offspring without feet.

In fact, scientists reproduce through this idea. For example, if they want to get chickens that grow faster, scientists will choose those chickens that grow faster as breeders. After several generations of artificial selection, the offspring of these chickens will contain genes that grow faster.

abstract

When an organism is inherited, it is not a specific trait, but a genetic gene, so it is not feasible to get a legless chicken by cutting off its feet.