[Edit this paragraph] Required reading reasons
Classical works that influence the course of world history.
One of the 10 books that shocked the world.
1985 American Life Magazine selected the best books in human history.
1986 ideal books recommended by reading magazine in Britain.
The theory of evolution expounded in this paper is one of the three great discoveries of natural science in the19th century. Owen (1809 ~ 1882) was born in Shrewsbury, western England, into a family of doctors for generations. 16 years old, was sent to the University of Edinburgh to study medicine. But Darwin liked hunting and collecting mineral and plant specimens since childhood. His father thinks he is idle. 1829, in a rage, he was sent by his father to Cambridge University to study theology, hoping to become an "outstanding priest". 183 1 year, Darwin graduated from Cambridge University. In 65438+February of the same year, the British government organized the warship "Beagle" to explore the world, and Darwin started the exploration at his own expense as a naturalist. The warship crossed the Atlantic and Pacific oceans, passed through Australia, crossed the Indian Ocean, bypassed the Cape of Good Hope, and returned to Britain at 1836 10. 1842, he wrote the outline of the Origin of Species for the first time. 1859165438+1October, after more than 20 years of research, Darwin finally wrote the scientific masterpiece "The Origin of Species". 1on April 9, 882, the great scientist died of illness and his body was buried next to Newton's grave.
Darwin himself called the origin of species a "long debate" and demonstrated two problems: First, species are changeable and organisms are evolutionary. At that time, most biologists who had read the Origin of Species quickly accepted the fact that evolution replaced creationism and became the cornerstone of biological research. Even then, the debate about whether organisms evolved was mainly between biologists and Christian missionaries, not in the field of biology. Second, natural selection is the driving force of biological evolution. Biologists at that time were hesitant to accept this because there were three difficulties in the theory of natural selection at that time.
First, there is a lack of transitional fossils. According to the theory of natural selection, biological evolution is a process of gradual change under the choice of environment, so there should be transitional forms between old species and new species, and between old species and new species, which can only be found in fossils. None of the fossil specimens found at that time can be considered as transitional. Darwin believed that this was due to the incomplete fossil record, and believed that further search would find some transitional fossils. Indeed, two years after the publication of the Origin of Species, the transitional archaeopteryx from reptiles to birds was unearthed, and various transitional fossils were discovered one after another, the most famous of which was the ape-man fossil from apes to humans. There are thousands of transitional fossils now, but compared with millions of known fossils, they are still very rare. There are two reasons for this. On the one hand, biological fossils are formed by accident, so the fossil record must be very incomplete; On the other hand, according to the popular "punctuated equilibrium" hypothesis, when organisms evolve, they often complete the evolution to new species in a short time after a long period of stability, so it is more difficult to form fossils in transitional forms.
Second, earth times. Since natural selection theory holds that biological evolution is a gradual process, it will take a very long time. Darwin believed that this process would take at least hundreds of millions or even billions of years. But william thomson (Lord Kelvin, a creationist), a master of physics at that time, proved by thermodynamic method that the earth was only 1 100 million years old, and only in the last 20 million years at most, the earth was cooled enough for life to survive. Darwin couldn't fight back against the challenge of physicists, just saying, "I'm sure that one day the world will be found to be older than Thomson's calculation." Today, we know that Darwin was right, but Thomson miscalculated. Now, geologists realize that the earth has a history of more than 4 billion years and life was born at least 3 billion years ago. But when it came to the age of the earth, people were obviously more inclined to believe in the authority of physics.
The third difficulty is the most fatal: Darwin could not find a reasonable genetic mechanism to explain natural selection. At that time, biologists generally believed in the so-called "fusion inheritance": the traits of father and mother were fused and passed on to future generations. It seems obvious that the skin color of children born to whites and blacks is always between black and white. According to this, F. Jenkin, a student of Thomson and a Scottish engineer, pointed out that a good mutation will be quickly merged and diluted by many inferior mutations, but it can't be preserved and spread in future generations like the theory of natural selection. Just like a white man marries a black African tribe and has children, his descendants will become completely black after several generations. Although Darwin knew from animal and plant cultures that a good character can be preserved, he did not have a reasonable genetic theory to refute Jane. Darwin was forced to make a concession, and admitted that Lamarckianism of "taking what has been used and discarding it" was also established, which can be used to supplement the theory of natural selection. In fact, before and after Darwin's death (1882), Lamarconism was generally accepted by biologists, while natural selection was doubted.
If Darwin had known about the experiment of Austrian geneticist Mendel, he would not have been in a desperate situation on genetic issues. Mendel discovered the phenomenon of gene separation and independent distribution in 1865. Biological inheritance does not fuse, but is transmitted randomly in units of genes. Therefore, as long as the population is large enough, a genetic trait will not disappear without the influence of external factors (such as natural selection) (the fusion of skin color is a superficial phenomenon under the action of several pairs of genes). Under the action of natural selection, an excellent gene can increase its frequency in the population and gradually spread to the whole population.
Obviously, Mendelianism is the genetic theory that Darwin needed. Unfortunately, Mendel's discovery was completely ignored by the scientific community at that time. Ironically, when Mendelianism was rediscovered in 1900, geneticists thought it declared the death of Darwinism. In their view, random gene mutation, rather than natural selection, is the real driving force of biological evolution. Only some biostatisticians who observe the behavior of wild animals and plants still believe in Darwinism, because the wonderful adaptability of creatures they observe to the environment cannot be explained by random mutation.
[Edit this paragraph] Executive summary
The Origin of Species is the first masterpiece of Darwin, the founder of evolution. The book is divided into fifteen parts, with introduction and introduction. The content of the fifteenth part is as follows: first, the change of domestic state; Second, the change of natural state; Third, struggle for survival; Fourth, natural selection (that is, survival of the fittest); Fifth, the law of variation; Sixth, the difficulty of theory; Seventh, various objections to the theory of natural selection; Eighth, instinct; Ninth, mixed nature; Tenth, the geological record is incomplete; Eleventh, the succession of paleontology; Twelfth, the geographical distribution of organisms; Thirteenth, the continuation of biogeographic distribution; Fourteenth, the genetic relationship between organisms: morphology, embryology and degenerated organs; Fifteenth, summary and conclusion. From the previous fourteen articles, we can clearly see the content of the Origin of Species: telling the process and law of biological evolution. The former 14 chapter can be divided into three parts, namely 1 to 5 chapters, 6 to 10 chapters,1to 14 chapters. The first part is the main body and core of this book, which marks the establishment of the theory of natural selection. In the second part, the author puts forward a series of questions about evolution from the standpoint of opponents, and explains them one by one to solve these problems. This shows the author's courage and the invincible vitality of the theory itself. In the third part, Darwin's theory of evolution with natural selection as the core convincingly explains various phenomena in biological historical evolution, geographical changes, morphological suitability and embryonic development, thus further supporting this theory.
Natural selection; survival of the fittest
Natural selection-the comparison between its power and the power of artificial selection-its power over unimportant features-it
For the power of all ages and sexes-sexual selection-about the universality of hybridization between individuals of the same species-about nature
The advantages and disadvantages of selection results are hybridization, isolation, number of individuals-slow action-natural selection.
Extinction caused by selection-the relationship between the difference of characters, the difference of organisms in any small area and domestication-
-natural selection, through the divergence and extinction of traits, the role of descendants of the same ancestor-all biological points
The explanation of species-the progress of biological system-the preservation of lower types-the convergence of characters-the infinite reproduction of species
-Summary.
The struggle for survival was briefly discussed in the previous chapter. How does mutation work? Great things happen in human hands.
Can the principle of action choice be applied to nature? I think we will see it happen very effectively.
It works. We should remember that there are countless tiny variations and individual differences in domestic organisms, and there are processes under natural conditions.
Countless tiny variations and poor individual differences; Also remember the power of genetic predisposition. In the domestic situation, you can
To be exact, he said, the whole biological system has become plastic to some extent. Domestication that we almost universally encounter.
Biological variation, as Hooke and Asa Gray said, is not directly produced by manpower; Humans cannot create.
Mutations cannot prevent them from happening; He can only save and accumulate the varieties that have happened, man.
Humans inadvertently put living things in a new and ever-changing living environment, so mutations occurred; But living conditions
Similar changes may occur under natural conditions. We should also remember the interrelationships of living things and their influence on the environment.
How complex and close the relationship between the material conditions of life is; Therefore, the infinitely divergent structure is in a constantly changing life condition.
There is always something useful about the creatures below. Since useful mutations must have occurred for human beings, in the vast and complex life,
In struggle for existence, other variations that are useful to every living thing in some ways are not in the process of successive generations.
Can't it happen? If this mutation does occur (it must be remembered that more individuals are produced than possible),
Then individuals who are superior to other individuals (even if the degree is slight) have the best chance to survive and reproduce.
Dai, what is there to doubt? On the other hand, we can be sure of any harmful variation, even the degree.
Very slight, but also severely damaged. I have preserved this beneficial individual difference and variation, as well as those harmful.
The destruction of mutation is called "natural selection" or "survival of the fittest". Useless and harmless mutations are not dominated by natural selection.
The role of selection, it either becomes a feature of hesitation, as we see in some polymorphic species, or eventually
Becoming a fixed character is determined by biological nature and external conditions.
Some authors misunderstand or object to the term "natural selection". Some people even imagine that natural selection can
Induced mutation, in fact, it can only keep those mutations that have occurred and are beneficial to organisms under the living conditions.
No one opposes what agronomists call the great role of artificial selection; However, in this case, you must first have natural hair.
Natural individual differences, and then human beings can make choices according to certain purposes. There are still some people who are opposed to choosing this.
Language, thinking that it contains such a meaning: the changed animals can make conscious choices; Even strongly advocate planting.
Since things have no will, natural selection cannot be applied to them! Literally, there is no doubt that nature has chosen this.
The term "a" is inaccurate; However, who ever objected to what chemists said about the selective affinity of various elements? strictly
It really can't be said that an acid chooses the base it is willing to combine. Some people say that I regard natural selection as a kind of motivation.
Or "divine power"; However, who objected to an author who said that gravity controls the motion of planets? Everyone knows that.
What does the metaphor of Tao mean? For the sake of simplicity, this term is almost necessary.
The word "nature" is inevitably personified; But when I say "nature", I only mean the synthesis of many natural laws.
Function and its product, and the law is the causal relationship of all kinds of things we have determined. Get familiar with it a little,
These superficial objections will be forgotten.
It is very good to study a place that is undergoing some slight physical changes, such as climate change.
Understand the general process of natural selection. As soon as the climate changes, the proportion of organisms there changes almost immediately.
Some species may become extinct. We can get it from the close and complicated relationship between creatures in different places that we know.
The conclusion is as follows: even if climate change is not mentioned, if there is any change in the proportion of organisms, it will be serious
Effectively affect other creatures. If the border of that area is open, new types will inevitably migrate in, which will be serious.
Disturbed the relationship between some primitive creatures. Please remember: the impact of introducing a tree or a mammal from other places is
How powerful; This has been clarified. However, on an island, or in a place partially surrounded by obstacles,
If the adaptable new type can't move in freely, there will be some places in the natural composition of the place, such as
If some primitive creatures have changed in some ways, they will certainly fill it up; Because if that area
If the domain had allowed free migration, alien creatures would have already achieved their status there. In this case, any slight change,
As long as it is beneficial to individuals of any species in any way, so that they can better adapt to changed external conditions,
Tending to be reserved; So natural selection has room to improve the work of biology.
As explained in the first chapter, we have every reason to believe that changes in living conditions will produce variability.
A growing trend; In the case described in the previous section, with the change of external conditions, the chance of favorable mutation will gradually increase.
Obviously, this is very beneficial to natural selection. If there is no favorable mutation, natural selection will not work. Don't forget.
Remember, the term "variation" only includes individual differences. Humans put individual differences in any given direction.
Accumulated, domestic animals and plants can produce great results, and so can natural selection.
And it's much easier because it has unparalleled long hours. I don't believe there will be anything huge.
Physical changes, such as climate change, or high isolation prevent migration, thus making some new vacancies, but,
Only through natural selection can some mutated organisms be improved and filled. Because all living things in all regions
Struggle with each other in a tight balance, a species' structure or habit has undergone subtle variation, which often makes it
Have advantages over other creatures; As long as this species continues to live in the same living conditions and has the same survival and
If the defense means gains benefits, the same variation will develop more and more, and its advantages will often become bigger and bigger. not yet
There is a place. All local creatures have completely adapted to each other and their living environment.
The conditions are completely adapted, and no one can adapt better or improve more;
Because in all places, foreign creatures often beat local creatures and firmly occupy this land. Exotic organisms are both
By defeating some local creatures in various places in this way, we can safely assert that local creatures will also undergo beneficial changes.
Different, in order to better resist those invaders.
Through planned and unconscious selection methods, mankind can produce and indeed produce great results.
Why doesn't natural selection work? Humans can only act according to external and visible characteristics: "nature"
If I am allowed to personify nature conservation or survival of the fittest-I don't care about appearances unless they are for the sake of
Biology is useful. "Nature" can affect all kinds of internal organs, all kinds of subtle physical differences and the whole living mechanism.
It works. Man only chooses for his own interests: "Nature" only chooses for the interests of the creatures she protects.
Benefit and make choices. All kinds of selected characteristics, as pointed out by the fact that they are selected, are completely influenced by the self.
Natural movement. Humans keep all kinds of creatures growing in different climates in the same place; He seldom uses anything special.
And practice each selected character through appropriate methods; He feeds pigeons with long noses and short noses with the same food; he
Don't use special methods to train quadrupeds with long backs or feet; He keeps sheep with long hair and short hair in the same atmosphere.
Hou Li, he doesn't allow the strongest men to compete for women. He doesn't strictly put all the bad habits
All his animals were destroyed, and all his creatures were protected within his power in different seasons. he
Often according to some types of semi-deformation, they begin to choose; Or at least according to some significant changes that attract his attention,
Or a mutation that is obviously beneficial to him, start choosing. In the natural state, something extremely subtle in structure or construction.
Differences can change the delicate balance of life struggle. So it was preserved. Human aspirations and efforts
That was a moment! How short human life is! Therefore, just like "nature" in all geological ages.
Compared with the product results, how poor the results obtained by human beings are! It seems that "natural" products are more important than human products.
However, it is much more "real" and can be infinitely adapted to extremely complicated living conditions, and it is obvious.
Out of the more advanced skills, what is worth our surprise?
We can compare him and say that natural selection is carefully examining the smallest variation every day and hour in the world.
Reject the bad, save the good and accumulate; Whenever and wherever there is an opportunity,
It works quietly and very slowly, connecting all kinds of living things with organic and inorganic living conditions.
Improvement. We can't detect this slow change unless there are signs of time passing. However, we are interested in
In the past long geological age, our knowledge is limited, and what we can see is that the current biological types are not quite the same as before.
The same.
If a species wants to achieve any large-scale variation, it will take a long time after the variation is formed.
During this period, favorable variations or individual differences of the same nature occur again; And these mutations must be preserved, such as
Well, step by step. Because the same individual difference occurs repeatedly, this assumption should not be regarded as
There is no basis. But whether this idea is correct or not can only be seen if it conforms to and can explain the common phenomena in nature.
Likes to judge. On the other hand, it is generally believed that variation has strict limits, and this belief is also a kind of no.
An out-and-out idea.
Although natural selection can only pass through and benefit all living things, it is usually considered extremely inappropriate for us.
Important traits and structures can also play a role in this way. When we see that insects that eat leaves are green, we eat them.
Insects with bark are light gray; Mountain grouse is white in winter, and Korean grouse is heather, so it must be
It must be believed that this color is to protect these birds and insects from danger. If a grouse is not killed at some point in its life,
Killing is bound to multiply to countless; We know that they are violently attacked by carnivorous birds; Eagles rely on their eyesight to hunt prey.
Eagle's eyesight is so keen that people in some parts of continental Europe avoid raising white pigeons because they are very easy.
Suffer. Therefore, natural selection shows the following effects, giving all kinds of grouse proper colors when they are once
Having obtained this color, natural selection makes it pure and permanently preserved. Let's not think that I
However, getting rid of an animal with a special color has little effect; We should remember that in a flock of Aries,
How important it is to get rid of a dark lamb. As mentioned earlier, pigs in Virginia will eat "Chigen"
Life and death are determined by their colors. As for plants, botanists look at the color of fluff and pulp of fruits.
Work is an extremely unimportant trait; However, we heard an outstanding gardener Tang Ning say that in America,
The weevil is more harmful to smooth fruit than soft fruit. Some disease is harmful to purple.
The harm of colored plum is far greater than that of yellow plum; Peaches with yellow flesh are more prone to some diseases than peaches with other flesh colors.
Hurt. If manual selection is used. All methods, such a small difference will make some varieties produce great results in cultivation.
Difference, then, under natural conditions, a tree is bound to fight against the same tree and a large number of enemies. At this time, this feeling
Different diseases will strongly determine which species-shiny or hairy skin, yellow or purple flesh.
Get success.
When observing many small differences between species (from our limited knowledge, these differences seem very different)
Important), let's not forget that climate, food and so on will undoubtedly have some direct effects on them. It must also be remembered that,
Because of the relevant laws, if some of them have mutation, and this mutation is accumulated through natural selection,
Other changes will follow, usually unexpected.
We know that in the domestic situation, those mutations that occur in any special period of life are often found in future generations.
Recurrence in the same period, for example, the shape, size and taste of seeds of many varieties of vegetables and crops; Silkworm metamorphosis
This is true of the larval and pupal stages of species, the fluff color of eggs and chickens, and the horns of sheep and cattle close to adulthood.
Similarly, under natural conditions, natural selection can also act on organisms at any time to make them change. as a result of
This can be done because natural selection can accumulate favorable variations during this period, and because of these favorable variations,
Can be handed down in the corresponding period. If plants benefit from seeds being blown far away, then through
Natural selection will achieve this, and its difficulty will not be greater than that of cotton farmers planting and improving cotton in gourd through selection methods.
Natural selection of velvet can mutate the larva of an insect and adapt to many accidents that adults can't meet; these
Variation, through association, can affect the structure of adults. Conversely, the variation of adults will also affect.
Larval structure; But in all cases, natural selection will ensure that those mutations are harmless, because if they are harmful,
This species is going extinct.
Natural selection can make the structure of offspring different from parents, and it can also make the structure of parents different from offspring.
In social animals, natural selection can adapt the structure of each individual to the interests of the whole; If this option is selected,
Variation benefits the whole. What natural selection can't do is to change the structure of a species without giving it any benefits.
But for the benefit of another species. Although I have talked about this effect in some natural history books, I haven't looked for it yet.
For example, if it is very important for an animal to use the structure only once in its life,
Then natural selection will cause great variation in this structure; For example, some insects' jaws are specially used to break cocoons, or
Hard beaks used by unborn chicks to peck through eggshells are everywhere. Someone once said: The best short-billed flying pigeon dies in an egg.
There are much more things in eggshells than hatched from broken eggs; Therefore, pigeon breeders should give help when hatching. So, suppose.
"Nature" makes a fully grown pigeon have a short mouth for its own benefit, so this mutation process is probably
The speed is extremely slow, and at the same time, the young pigeons in the eggs should be strictly selected, and the strongest pigeons will be selected.
Young pigeons, because any weak young pigeon will inevitably die; Or, you will choose those fragile eggshells.
As we know, the thickness of eggshells, like other structures, is variable.
It may be useful to explain here that all living things are bound to be destroyed in large numbers by accident.
But this has little or no influence on the process of natural selection. For example, there are a lot of eggs or seeds every year.
Seeds are eaten, and only when there are some variations can they be naturally selected and changed to avoid being swallowed up by the enemy.
However, if many of these eggs or seeds are not eaten and become individuals, they may be better than any individual who happens to survive.
Better adapt to the living environment. Moreover, most growing animals or plants are good at adapting to their lives.
No matter what the living conditions are, they are bound to be destroyed every year for accidental reasons; Although some changes have taken place in their structure and physique
These changes are beneficial to species in other ways, but this accidental death will not be alleviated. However, even if
So many growing creatures are destroyed, if the number of individuals who can survive in various regions is not due to such accidental reasons.
Therefore, all of them are eliminated-or even if so many eggs or seeds are destroyed, it is only one percent or one thousandth.
A person can develop, and then the most adaptive individual among those living creatures, if for any one.
If the favorable direction changes, other families will be able to reproduce more offspring than individuals with poor adaptability. If everyone
Being eliminated for the above reasons is often seen in practice, so natural selection will not be beneficial to some directions.
I can do something. But we can't oppose the effectiveness of natural selection in other periods and other aspects; Because we really didn't.
There is no reason to assume that many species have mutated and improved in the same period and area.
-Summary of this chapter:
Under the changing living conditions, almost every part of the biological structure has to show individual differences, which is indisputable.
Open; Due to the increase of the ratio of bio-geometry, they have a fierce struggle for existence at a certain age, season or age.
Controversy, this is indeed indisputable; Therefore, considering the infinity between all living things and their living conditions.
Complex relationships will lead to infinite differences in structure, physique and habits that are beneficial to you. If we say never,
There has never been any variation beneficial to the prosperity of every living thing itself, just as there have been many changes beneficial to mankind.
Being different is a very strange thing. However, if a variation beneficial to any living thing does occur, then it is.
Individuals with this trait will have the best chance to save themselves in the struggle of life; According to strong heredity
In principle, they will produce offspring with the same characteristics. I call this preservation principle, that is, the survival of the fittest, as follows.
"Natural selection". "Natural selection" leads to biological improvement according to organic and inorganic living conditions; Therefore,
It must be admitted that in most cases, it will lead to an improvement of the system. However, low-level and simple types such as
The greatest epoch-making milestone in the history of human thought development.