The Origin of Species
"When we reflect on this struggle, we may console ourselves with the full belief that the war of nature is not incessant, that no fear is felt, that death is generally prompt, and that the vigorous, the healthy, and the happy survive and multiply".
General Overview
All living beings have descended from common ancestors through a process called natural selection, which is the main but not exclusive means of modification and co-adaptation. Living things are not fixed, they are capable of change and their structure is adapted to the environment in which they live.
All living beings have descended from common ancestors through a process called natural selection, which is the main but not exclusive means of modification and co-adaptation. Living things are not fixed, they are capable of change and their structure is adapted to the environment in which they live.
Chapter 1 Variation Under Domestication
Darwin introduces us to the idea of variation, in which he states clearly that the reproductive system is the main reason that causes variability. The results are very complex. He also states the importance of the accumulative action of selection, which is the more predominant power on variability. He explains natural selection in terms of human domestication and emphasizes that any variation, which is not inherited, is not important for the argument.
Variation under domestication
Selection
"Over all these causes of Change I am convinced that the accumulative action of Selection, whether applied methodically and more quickly, or unconsciously and more slowly, but more efficiently, is by far the predominant Power".
Darwin introduces us to the idea of variation, in which he states clearly that the reproductive system is the main reason that causes variability. The results are very complex. He also states the importance of the accumulative action of selection, which is the more predominant power on variability. He explains natural selection in terms of human domestication and emphasizes that any variation, which is not inherited, is not important for the argument.
- Darwin believes that the cause of variability is in the reproductive elements prior to conception.
- There is more variability under domestication than in nature.
- Pigeons are descendant of the same ancestor.
- Selection determines variability.
Variation under domestication
- Between the varieties there’s more difference in domestication than in nature.
- Variability is caused by the reproductive elements affected, which happens prior to the act of conception. Reasons: Confinement and cultivation, habit.
Selection
- Direct action of external conditions of life
- Habit
- Adaptation
- Man modifications
"Over all these causes of Change I am convinced that the accumulative action of Selection, whether applied methodically and more quickly, or unconsciously and more slowly, but more efficiently, is by far the predominant Power".
Chapter 3 Struggle for Existence
All organisms struggle for survival.
Natural Selection
- Struggle for survival between various species and between the same species.
- "Every being...must suffer destruction during some period of its life, and during some season or occasional year, otherwise, on the principle of geometrical increase, its numbers would quickly become so inordinately great that no country could support the product".
- Every organism is bound to destruction.
1. Every being strives to increase its number.
2. Each being struggle at some point of its life.
3. Heavy destruction is inevitable during each generation.
-Complex relationships between beings emerge; they cooperate with one another in their struggle for survival.
-Competition will never cease, only the fittest survive and multiply.
All organisms struggle for survival.
- Any variation, if profitable, will tend to the preservation of that individual. (Natural Selection)
- Competition exists for the sake of surviving.
- If conditions of life have been favorable, plants and animals, tend to increase at a geometrical ratio.
- Organisms are bound by complex relationship; they “cooperate” with one another.
Natural Selection
- Struggle for survival between various species and between the same species.
- "Every being...must suffer destruction during some period of its life, and during some season or occasional year, otherwise, on the principle of geometrical increase, its numbers would quickly become so inordinately great that no country could support the product".
- Every organism is bound to destruction.
1. Every being strives to increase its number.
2. Each being struggle at some point of its life.
3. Heavy destruction is inevitable during each generation.
-Complex relationships between beings emerge; they cooperate with one another in their struggle for survival.
-Competition will never cease, only the fittest survive and multiply.
Chapter 4 Natural Selection
Natural selection strives for preservation of favorable variations and rejections of injurious variations.
“Natural selection can act by the preservation and accumulation of infinitesimally small inherited modifications, each profitable to the preserved being…”
Natural Selection modifies
1) Modify the parent - young
2) Modify relationship young- parent
3) Adapt the structures of each individual for the benefit of the community
1. Intercrossing keeps individuals of the same species in a true and uniform character.
2. Isolation means that in an isolated area, all the species will modify in the same manner in relation to the same conditions and checks the immigration of better-adapted organisms.
Divergence Character: Early differences, continued by time and natural selections, differences become greater, sub-breeds are formed, after centuries, sub-breeds become breeds.
Principle: At first, the differences are barely noticed, then they increase and then breeds arise that are different from them and their parents.
"As buds give rise by growth to fresh buds, and these, if vigorous, branch out and overtop on all sides many a feebler branch, so by generation I believe it has been with the great Tree of Life, which fills with its dead and broken branches the crust of the earth, and covers the surface with its ever branching and beautiful ramifications".
Natural selection strives for preservation of favorable variations and rejections of injurious variations.
“Natural selection can act by the preservation and accumulation of infinitesimally small inherited modifications, each profitable to the preserved being…”
Natural Selection modifies
1) Modify the parent - young
2) Modify relationship young- parent
3) Adapt the structures of each individual for the benefit of the community
- Natural selection can’t modify the structure of the species without giving it advantage to other species.
- The process of modification is very slow.
- Beings are modified in the same degree as its competitors, if not they are exterminated.
1. Intercrossing keeps individuals of the same species in a true and uniform character.
2. Isolation means that in an isolated area, all the species will modify in the same manner in relation to the same conditions and checks the immigration of better-adapted organisms.
Divergence Character: Early differences, continued by time and natural selections, differences become greater, sub-breeds are formed, after centuries, sub-breeds become breeds.
Principle: At first, the differences are barely noticed, then they increase and then breeds arise that are different from them and their parents.
"As buds give rise by growth to fresh buds, and these, if vigorous, branch out and overtop on all sides many a feebler branch, so by generation I believe it has been with the great Tree of Life, which fills with its dead and broken branches the crust of the earth, and covers the surface with its ever branching and beautiful ramifications".
Chapter 6 Difficulties in Theory
There are three difficulties in theory:
1. Gaps in the fossil record
2. Complex structures
3. Elaborate instincts
Extinction and natural selection go hand in hand. It’s difficult to see the work of natural selection because of the gaps of fossils, i.e. we don’t have every single fossil.
“Natural selection will pick out with unerring skill each improvement”.
“On the theory of natural selection, we can clearly understand why she should not; for natural selection can act only by taking advantage of slight successive variations; she can never take a leap, but must advance by the shortest and slowest steps”.
There are three difficulties in theory:
1. Gaps in the fossil record
2. Complex structures
3. Elaborate instincts
Extinction and natural selection go hand in hand. It’s difficult to see the work of natural selection because of the gaps of fossils, i.e. we don’t have every single fossil.
- Natural selection takes time, it doesn’t happen fast. Complex structures can be formed from imperfect and simple structures by natural selection in a vast amount of time. As we have read before, the better or new modification is preserved and the old ones destroyed".
“Natural selection will pick out with unerring skill each improvement”.
- In nature, an organ may be constructed for one purpose can be turned or modified to serve another purpose.
“On the theory of natural selection, we can clearly understand why she should not; for natural selection can act only by taking advantage of slight successive variations; she can never take a leap, but must advance by the shortest and slowest steps”.
Chapter 11 Geographical Distribution
“It seems to me…that the view of each species having been produced in one are alone, and having subsequently migrated from that area as far as its powers of migration and subsistence under past and present conditions permitted, is the most probable”.
- The evolution of animals and plants is due to the pattern of landmasses not to the climatic conditions because the climate among areas is very similar. Oceans and long distances separate landmasses from one another, which causes that each area has its unique fauna and flora.
- Darwin states that each species is a unique production of nature happening in a localized region of space and time, if this species seizes it will not occur again. Earth climate changes over time, the climate today is very different than a couple of centuries ago.
“It seems to me…that the view of each species having been produced in one are alone, and having subsequently migrated from that area as far as its powers of migration and subsistence under past and present conditions permitted, is the most probable”.
- Ice ages changed the surface of the Earth and separated populations.
Chapter 14 Recapitulation and Conclusion
Darwin has the belief that all animals and plants have descended from some one prototype.
“Nevertheless all living things have much in common, in their chemical composition, their germinal vesicles, their cellular structure, and their laws of growth and reproduction”.
“Therefore I should infer from analogy that probably al the organic beings which have ever lived on this earth have descended from some primordial form, into which life was first breathed”.
Darwin has the belief that all animals and plants have descended from some one prototype.
“Nevertheless all living things have much in common, in their chemical composition, their germinal vesicles, their cellular structure, and their laws of growth and reproduction”.
“Therefore I should infer from analogy that probably al the organic beings which have ever lived on this earth have descended from some primordial form, into which life was first breathed”.
- He knows that his theory will open new inquiries, investigations, doubts and discoveries.
“It is interesting to contemplate an entangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent on each other in so complex a manner, have all been produced by laws acting around us. These laws, taken in the largest sense, being Growth with Reproduction; Inheritance which is almost implied by reproduction; Variability from the indirect and direct action of the external conditions of life, and from use and disuse; a Ratio of Increase so high as to lead to a Struggle for Life, and as a consequence to Natural Selection, entailing Divergence of Character and the Extinction of less improved forms. Thus, from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows. There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.”