The Origin of Species, Charles Darwin

• Darwin considered this book as “one long argument” for his view of life
• The fiercest struggle for existence is among members of the same species, as they occupy the same areas, require the same foods, and are exposed to the same dangers

  Chapter 1: Selection by man

• Darwin has this to say about breeders who doubt that distinct breeds could have come from a common ancestor: “from long-continued study they are strongly impressed with the differences between the several races; and though they well know that each race varies slightly, for they win their prizes by selecting such slight differences, yet they ignore all general arguments, and refuse to sum up in their minds the slight differences accumulated during many successive generations”
• In domesticated races we see in them adaptation, not to the animal’s or plant’s own good, but to man’s use or fancy
• Man can hardly select any deviation of structure except what is externally visible; and rarely cares for what is internal
• A fancier perceives extremely small differences, and it is in human nature to value any novelty, however slight, in one’s own possession

  Chapter 2: Variation under nature

• B.D Walsh, an entomologist, suggested that forms that could freely intercross were varieties, and those who lost this power were species — earliest distinction of species vs. variety?
• The term species used to be considered as a useless abstraction, uniting and assuming a separate act of creation
• Distinguishing between species and variety is a struggle, since organisms adapt via a continuous process, thus species/varieties occupy a continuum. Distinguishing between a separate species/variety thus requires some abstract threshold

  Chapter 3: Struggle for existence

• Natural selection comes by analogy of breeders “selecting” for optimal plants/animals, and nature doing the equivalent thing unconsciously
• Species develop adaptations as they struggle for life against other species. The fiercest competition tends to occur between close varieties or subspecies, as they occupy the same areas, eat the same food, etc.

  Chapter 4: Natural Selection; or Survival of the Fittest

• “…I mean by Nature, only the aggregate action and product of many natural laws, and by laws the sequence of events as ascertained by us.”
• P112, good quote about how selection by man pales in comparison to natural selection
• Intercrossing seems to be conducive to genetic success. Hermaphrodite plants and animals, despite having both sex cells, still require intercrossing to breed, and rarely reproduce successfully with themselves despite close spatial proximity of their sex organs
• Hermaphrodites tend to profit off insects or fluid currents (wind or water) to transport their sex cells to other organisms
• Animals with separate sexes need to do the sexual delivery themselves, so are fitted with behaviours that bring them together in space and time (since the currents or insects can’t do it for them), a sexual magnet of sorts
• Organisms occupying larger areas are exposed to more competition, and thus have greater ability to adapt into new varieties and species. They will be better adapted than species from smaller isolated areas, by virtue of having more competition to train from. These organisms thus play a more important part in changing the history of the organic world
• Smaller confined areas produce organisms that are less varied and experience less severe competition. When organisms from a larger region come in (e.g., from Asia to Australia), they tend to dominate due to their better generalizability
• Rare species are less quickly modified or improved within any given period, consequently being beating in the race for life by modified and improved descendants of commoner species
• The more diversified in habits and structure the descendants of organisms become, the more places they can occupy
• Natural selection leads to the improvement of each creature in relation to its organic and inorganic conditions of life, and what may be regards as an advance in organization
• The Tree of Life fills the crust of the earth with its dead and broken branches, and covers the surface with its ever-branching and beautiful ramifications

  Chapter 5: Laws of variation

• Disuse leads to natural selection removing unnecessary organs. Subterranean creatures tend to be blind, beetles near a coastline develop either no wings or stronger wings to avoid/overcome coastline breezes. o Disuse reduces investment in that feature. This goes with behaviour. A bad habit fades away if one manages to place themselves in an environment where it can’t be of use (like the eyes of a mole)
• Sexual selection is less rigid in its action than ordinary selection, as it does not entail death, but only gives fewer offspring to the less favoured individuals
• “I would almost as soon believe that the old and ignorant cosmogonists, that fossil shells had never lived, but had been created in stone so as to mock the shells living on the seashore.”

  Chapter 6: Difficulties of the theory

• One objection to the theory is how it can account for the “perfection” of specialized organs, for example, the eye. Darwin goes on to explain that gradual changes could very well lead to eyes over long time periods, early light sensing via a convex sense organ is seen in starfish
• Then goes to point that the closer you look, the less perfect things become. Our respiratory tract and digestive tract intersect each other, which is terrible design! This is an artifact from our ancestors that evolution didn’t overwrite, as it didn’t pose enough of a threat to survival

  Chapter 7: Miscellaneous objections to the theory of natural selection

  Chapter 8: Instinct

• Habit is behaviour obtained through repetitive experience; instinct is more innate (the repetitive experience in this case is amassed and ingrained over innumerable generations)

  To be continued…