To explain the mechanism of natural selection, he wrote specifically what he meant in the first two paragraphs of chapter 4 of the book On the Origin of Species * This passage is reproduced here
For over twenty years, Darwin collected vast amounts of scientific data that clarified for him the subject of how plants and animals change their form over long periods of time. In addition to founding the science of evolutionary biology, Darwin also achieved achievements in the field of geology and collected many fossils from many rock types during his five-year voyage on the Beagle. As a result of this activity, he became aware of the enormous age of the earth.
He also studied the mutations that resulted from the hybridization experiments he performed on domestic animals and plants. He was also able to organize all this information when he tried to develop a mechanism of differentiation that caused the animals and plants to change over time.
In the end he realized that the mechanism behind the evolution process is "natural selection". The idea led him to publish on November 24, 1859 the book "On the Origin of Species" which is undoubtedly one of the most impressive books written in the last two hundred years.
To explain the mechanism of natural selection, he wrote in the first two paragraphs of chapter 4 of the book On the Origin of Species. (The editor of the scientist comments that on the Yom Darwin website, from which this page is taken, the paragraphs are given in their original text. We will quote them here from the Hebrew edition translated by Shaul Adler that was first published in 1960 by Mossad Bialik and reprinted in 1997. This is why the language is a bit outdated, as for example the usage in the term "natural clarification".)
The natural clarification or leaving the most capable
By Charles Darwin, Chapter 4 of the book "The Origin of Species"
The war of existence discussed briefly in the previous chapter, how will you act on the change? Is the principle of clarification, which is as powerful as we have seen in the hand of man, adapted to the conditions of nature? I think we will prove that he can act very efficiently. Women for the only slight changes that are endlessly multiplied, that arise in domesticated animals and plants, much less in nature, and added to this the power of hereditary tendency. It can truly be said that under domestic conditions the whole ole becomes somewhat flexible. But the variability that we almost always find in domesticated creatures is not man-made as Hooker and Aza Gray rightly observed. He cannot create varieties or prevent their formation; He can only keep and accumulate those who come and become.
Unintentionally a subject is organic creatures in new and transitory living conditions, and the result is change; But similar changes may and do indeed come in natural conditions as well. Please remember how infinitely complicated and how tight the mutual relations and material conditions of organic beings as a whole are; And hence the differences in structure, which differ endlessly, which may be beneficial to every creature in the changes and transformations of the conditions of life. Isn't it evident in light of the changes beneficial to man that have undoubtedly come and happened, that other changes, which are beneficial to every creature in some way in the great and complicated war of the seas, will come in the course of many successive generations?
And if such changes really come, can we doubt (if we remember, that the number of births is much greater than the number that can stay alive), that individuals with the slightest advantage over others will have the best chances to stay alive and stand up for their species? And on the other hand, we can be sure that any change that is harmful to its owner will be completely eradicated. To preserve single useful differences and changes and to contain those that are harmful to their owners I have called natural clarification or retention of the most capable. Changes that do not increase or decrease will not be affected by natural clarification and will remain a subject that can fluctuate as we see in the cases of multiform species, or in the end these changes will be permanent due to the nature of the creation and the conditions.
Some authors did not understand the term natural inquiry or grew up with it. Some of them even thought in their minds that the false clarification causes change, but really it is only aimed at preserving those changes that have come, and they are beneficial to the creation in the conditions of its life. No one disputes the farmer's words about the enormous results of the investigation in the hands of man; And in this case, the same differences from nature will apply in the first place, which man chooses for any purpose. Others have objected on this ground that clarification implies a choice out of recognition by animals that are changing: and it is also said that deer and plants are unwilling, natural clarification does not apply to them; There is no doubt that natural clarification is an incorrect term if we come to interpret it literally, but has anyone ever objected to the words of chemists who talk about connections according to the affinities of the various elements? And it cannot be said on the side of the severity of accuracy, that acid literally distills the base, which it prefers to connect with. It has been asserted that I speak of natural inquiry as if it were an active power in the hands of God. But who opposes the writer who stands for gravity, who is ruler of the movement of the planets? Everyone knows the meaning and allusion of exhortations and the like; And they are almost necessary for the sake of brevity. And it is also difficult to avoid humanizing the name nature, and by the word nature I mean the totality of the action and the result of many natural laws, and by the word 'laws' I mean the order of events to the extent that we approve of them. A little habit makes you forget such superficial claims.
It is beneficial to understand the apparent course of natural clarification after studying the case of a country, in which there has been a slight physical change, for example in the climate. Almost immediately after that, the ratio of the number of species inhabiting the place will change, and it is most likely that some species will become extinct. In light of everything we have learned about the complicated and tight mechanism by which the residents of each country recognize each other, we can come to the conclusion that any change in the number of some of the residents of their species, even when it does not depend on climate changes, will naturally have a significant effect on the rest of the residents. If the country's borders are open, new animals will undoubtedly immigrate into it, and this will also undoubtedly violate the quantitative ratio between the rest of the inhabitants. It is worth remembering how great was the influence of one species, tree or mammal, introduced into one country. But if this land is an island or is surrounded by barriers that prevent the free entry of animals from the outside whose power is greater (than the inhabitants of the place) in terms of adaptation, there will be a place in the natural economy that would be better filled if some species of the inhabitants of the place would transform in some way because if the place were open The entry of immigrants would be seized by invaders. In these cases there will be a tendency to preserve light shoots in favor of individuals of the same species by better adapting them to their new and different conditions, and natural clarification will have a free hand in the act of improvement.
Yadan Darwin and his teachings
For the article on the Darwin Day website
