Javier A. Tabush

ORIGIN OF THE SPECIES

Chapter 1: Variation under domestication

 

• He is comparing domesticated animals with animals not under confinement in the sense of breeding

• Correlation of growth: Any change in the embryo or larva will almost certainly entail changes in the mature animal.

• "The effects of variability are modified by various degrees of inheritance and of reversion. Variability is governed by many unknown laws, more specifically by that of correlation and growth." 

 

Chapter 3: Struggle for existence

 

• Darwin concluded that nature exhibits a tremendous degree of variation; enough to generate all the races, varieties and sub-varieties. 

• Principle of natural selection: "By this term, in order to mark its relation to man's power of selection. We have seen that man by selection can certainly produce great results, and can adapt organic being to his own uses. But Natural selection, as we shall hereafter see, is a power incessantly ready for action, and is as immeasurably superior to man's feeble effort, as the works of Nature are to those of art." (Pag. 32) 

• Corollary on the chapter: 

1. That the structure of every organic being is related to that all other organic beings. 

2. Each organic being is striving to increase at a geometrical ratio, that had to struggle for life as to suffer great destruction. 

 

Chapter 4: Natural Selection

 

-       Natural selection strives for preservation of favorable variations and rejections of injurious variations. 

Physiological division of labor: 

• "As more complete separation of the sexes of our plant would be advantageous on the principle of the divisions of labor individuals with this tendency more and more increased, would be continually favored or selected, until at last a complete separation of the sexes would be affected." (52)

•   He states the four difficulties and objections to his theory.

•   He explains the first one (on the absence or rarity of transitional varieties), and defends it.

•   He explains the second difficulty (organs of extreme perfection and complication), and defends it.

• Conclusions on why nature does not make leaps.

 

CHAPTER 6: DIFFICULTIES ON THEORY

 

• In this chapter Darwin addresses two questions:

  • Do species have gradually descended from other species?

  • Can natural selection really produce highly complex organs?

• Darwin argues that natural selection requires that intermediate varieties become extinct.

• Undeveloped, useless organs

• Science cannot always assume the importance of a particular variation.

• Over time species become perfectly adapted to their environments.

 

 

CHAPTER 11: GEOGRAPHICAL DISTRIBUTION

 

• Geographical isolation

• Migration in development of the species in specific environments

• Different climates support different species

• Geographical changes limit but also allow different species to migrate.

• “The dissimilarity of the inhabitant of different regions may be attributed to modification trough natural selection, and in a quite subordinate degree to the direct influence of different physical conditions”

• There are two major geographical changes that Darwin mentions to us throughout the chapter

  • The glacial period

  • A connection between land stretching from Western Europe through Siberia, now covered by the Bering Strait.

CHAPTER 14: RECAPITULATION AND CONCLUSION

 

• “There is a 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 wonderful have been, and are being, evolved”

• Darwin claims that his theory will lead to a revolution in science.

• Conflict between Darwin, and the naturalists and geologists because they reject his theory of descent with modification.