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What are the aspects of biological evolution?
Biological evolution, or evolution for short, is one of the most basic theories in biology. Evolution refers to the process of evolution and development, species elimination and species generation under the action of variation, heredity and natural selection. There is no life on the earth. Primitive life was formed about 3 billion years ago under certain conditions. Since then, organisms have evolved continuously, and today there are more than 6.5438+0.7 million species in the world. The theory of biological evolution was first put forward by charles robert darwin, and it was discussed in detail in his masterpiece The Origin of Species. There are three classical evidences of evolution: comparative anatomy, paleontology and the law of embryo development recurrence.

Darwin (1809 ~ 1882) is an outstanding British biologist and the main founder of evolution. Darwin's theory is a huge scientific system, but the center of the theory is selection, especially natural selection. Natural selection is based on artificial selection.

(1) artificial selection theory. He believes that many domestic animals and cultivated plants now originate from wild groups. Under the planned choice of human beings, it is actually a process of survival of the fittest to gradually accumulate and enhance the variation beneficial to human beings. This theory has three elements: first, there are variations; Second, this variation can be inherited; Third, humans can choose mutation. All three are indispensable.

(2) The theory of natural selection. First of all, Darwin believed that there was universal variation in living things. All creatures have variation characteristics, and there are no two identical creatures in the world. Variation can be divided into certain variation and not necessarily variation. The so-called certain variation means that the descendants of the same ancestor may produce similar variation under the same conditions. Such as the hot and cold weather and the thickness of fur, the richness of food and the size of individuals. The so-called indefinite variation refers to different variations produced by different individuals from the same or similar parents under the same or similar conditions. Just like lambs born by white ewes, they may be white, black or other colors. At the same time, Darwin believes that organisms generally have high reproduction rate and bottom-up competitiveness. Organisms tend to over-reproduce, but only a few individuals in each organism can develop and reproduce due to the limitations of food and space. Darwin also believes that in the competition for survival, the mutant individuals that are conducive to survival are retained and the mutant individuals that are not conducive to survival are eliminated. This is natural selection or survival of the fittest. Adaptation is the result of natural selection. In the process of natural selection, only the fittest can survive, and adaptation is only relative to survival. Once the living environment changes, the original adaptation may become unsuitable. Finally, Darwin believed that new species were formed by natural selection.

In the past half century, due to the rise of molecular biology, molecular genetics and population genetics, combined with the new achievements of other branches of biology, a new viewpoint on biotransformation has been put forward, that is, modern Darwinian theory, or comprehensive purchasing mechanism theory. This theory holds that organisms are realized in groups, and its main arguments are as follows: ① mutation (Darwin's infinite mutation, that is, gene mutation or chromosome aberration). It provides raw materials for biological procurement. ② Gene frequency and genetic balance. Causal frequency is the number of genes in a population. Under certain conditions, the gene frequency of a population's offspring and parents can remain unchanged, and the stable state of this gene in each generation is genetic balance. The evolution of living things is realized by population. ③ Natural selection and evolution of gene frequency. The evolution of population marks the change of gene frequency. The change of gene frequency is mainly caused by mutation and gene migration between populations. These factors must be guided by natural selection to directionally change the gene frequency of populations. ④ Fitness and selection pressure. Adaptability refers to the ability of organisms to survive and reproduce and to pass on genes to their offspring. The so-called selection pressure refers to the measurement of the effect of natural selection on a population. ⑤ Isolation. The formation of new species has three stages: mutation → selection → isolation. Because of geographical isolation, under the action of natural selection, morphology, habits and even structure further differentiate, resulting in reproductive isolation, and then form new species.

When I was an undergraduate in physical science and a graduate in biology at the University of California, Berkeley, I believed every word in the textbook I read. I know that there will be typos and small mistakes in textbooks that are contrary to the facts. I also have doubts about their philosophy beyond evidence, but I think my education is basically true.

However, when I was about to finish my Ph.D. in Cell and Developmental Biology, I found that in all my textbooks, the part about biological evolution was obviously misleading: just like the very similar pictures of vertebrate embryos, it showed the so-called evidence from the same ancestor. But as a developmental biologist, I know these photos are fake. They not only distorted the embryos they claimed to represent, but also deliberately left out the earliest embryos, because they were actually very different.

My evaluation of the embryo map was confirmed in 1997. Michael Richardson, a British embryologist, and his collaborators published a paper in Anatomy and Embryology, comparing the pictures in textbooks with the real embryos. Later, the American pioneer magazine Science quoted him as saying: "It seems that this has become the most famous fake in biology. 」

Unfortunately, most people don't know the truth, and even the biology textbooks published after 1997 still use these fake pictures. Since then, I have found that many other textbooks have distorted the evidence of evolution. At first I thought it was incredible. How can so many textbooks contain so many false certificates for a long time? Then I found that other biologists had long known most of the mistakes and published articles criticizing them. But their criticism was ignored.

The persistence of this phenomenon is obviously not a simple mistake. This at least shows that Darwinism encourages distortion of facts. It remains to be seen how many are unintentional mistakes and how many are intentional. But the consequences are obvious: both students and the public are systematically instilled with false information about the evidence of evolution.

This book is about making evidence. To prove it one by one, I quoted hundreds of scientists in my peer-reviewed articles, most of whom believed in Darwin's theory of evolution. I quoted them not to give people the impression that they are against evolution (most of them are not), but because they are experts in this evidence.

Science is inseparable from evidence.

The brochure of the National Academy of Sciences put it well, "In principle, when new evidence appears, all scientific knowledge should be changed. No matter how long this theory has been accepted, or how many scientists still believe it now. If there is evidence to the contrary, the theory must be re-evaluated or even abandoned. Otherwise, it is not science, but myth.

If an ordinary citizen is allowed to test the evidence, he should also be able to understand and judge the right and wrong of many sciences. The booklet of the National Academy of Sciences begins with Thomas Jefferson's appeal: "Let knowledge permeate the people. There is no other solid foundation to maintain freedom and happiness. The booklet goes on to say, "Jefferson foresaw an increasingly obvious thing: the fate of a country is based on whether people can understand and use the information provided by the world around them." " 」

My firm belief in writing this book is that scientific theories in general and evolution in particular can be evaluated by any intelligent person as long as he can examine the evidence. But before looking at the evidence of evolution, we must know what evolution is.

What is evolution?

According to the theory of biological evolution, all living things are descended from the same ancestor in ancient times, through inheritance and change. It claims that you and I are descended from the ancestors of "apes", but in fact we are descended from simpler animals.

This is the main meaning of "evolution" that biologists think. According to the brochure of the National Academy of Sciences, "the theory of biological evolution explains that all living things have the same ancestor. As time goes on, evolution changes to produce new species. Darwin called this phenomenon "bloodline with modification", which is still a good evolutionary definition until today. 」

For Darwin, except for the first creature, the gradual change of offspring is the source of all creatures. In the Origin of Species, he said, "I think all living things are not created alone, but descendants passed down from generation to generation by a few living things (in ancient times). Darwin explained that there are great differences between creatures today because they have been changed by natural selection or survival of the fittest. " I firmly believe that natural selection is the most important thing, but it is not the only way to change biology. 」

In response to criticism, supporters of Darwin's theory sometimes claim that the meaning of "evolution" only changes with time. However, this is obviously an evasive statement. No normal person would object that change is a part of reality, and we don't need Darwin to convince us. If this is all about evolution, there is no dispute. No one believes that evolution is as simple as changing with time.

Slightly mild, evasive avoidance admits that there is such a thing as gradual changes in offspring. Of course, because all creatures of the same species are gradually propagated by descendants. We can be seen in our own families, and people who keep animals and plants can be seen at work. that this is not the important question.

No one doubts that normal organisms will mutate during reproduction. The question is whether the gradual change of offspring can produce new species-more importantly, all biological species. Just like changing with time, the gradual change of offspring is no problem at the level of species. But Darwin's theory of evolution is more inclusive. In particular, it claims that the gradual change of offspring can explain the origin and diversity of all living things.

The only way to determine whether this statement is correct is to test it by experiment and observation. Darwin's theory of evolution, like all other scientific theories, must be constantly tested by evidence. If it is inconsistent with the evidence, it must be re-evaluated or abandoned, otherwise it will no longer be a science and become a myth.

Evidence supporting evolution

If most people, including most biologists, are asked to list the evidence supporting Darwin's theory of evolution, they will all give the same series of examples, because they all learn from the same textbooks. The most common examples are:

In an experimental glassware, an atmosphere simulating the early days of the earth is injected, and electric flowers are added to produce chemical components needed by living cells;

Life evolutionary tree, a picture integrated from a large number of increasing fossil records and molecular biological evidence;

In the wings of bats, flippers of dolphins, feet of horses and hands of humans, the structures of bones are very similar, indicating that they all evolved from the same ancestor.

The images of early animal embryos, including amphibians, reptiles, birds and humans, are very similar, indicating that they are all descendants of animals such as fish;

Archaeopteryx, a fossil bird with teeth in its mouth and claws on its wings, is the lost connection between ancient reptiles and modern birds.

The pepper moth on the trunk shows that protective color and birds preying on it constitute the most famous examples of natural selection in evolution;

Darwin's finches in the Galapagos Islands of Garaba have produced thirteen different species from a bird through natural selection on different islands, each with a different beak shape. Inspired by this, Darwin founded the theory of evolution;

Drosophila with a pair of wings shows that mutation can provide the raw materials needed for evolution;

The fossils of horses form a picture like branches, which overturns the old idea that evolution is directional; also

The evolution from an ape-like animal to a human shows that we are just animals, and our existence is only a by-product of a purposeless natural process.

These examples are often used as evidence to support Darwin's theory, and most of them are called "icons" of evolution. But in fact, they each distorted the facts in different ways.