In chapters eleven and twelve, Darwin discusses geological barriers to migration of species and how species moved from one side of the world to another. He writes his observations about how species on islands are very specific to that island and often found nowhere else in the world, because they are unable to leave that island. Also, however, he notes that many times species on islands are similar to the land masses next to them. The famous example of the Galapagos Islands, for instance- many of the creatures found on those islands can only be found on those islands, however, many of them bear resemblances to species in South America. He notes that species that are able to migrate more freely and that are suitable to a wide range of environments are far more common throughout the world. Even with plants, he mentions that plants that create seeds with barbs are found more commonly than those without, because the barbs make it easier for animals to carry them larger distances.
In this chapter of Origin of Species, Darwin brings up one instance in nature that could dismantle his entire theory of natural selection and inheritance of traits. In some ant species, the worker ants, which vary from the non-worker ants in both structure and instinct, are sterile. If these ants are unable to produce offspring, how could their traits be inherited by subsequent generations? He concludes, rather unconvincingly, that natural selection is not limited to a creature by creature basis but to species as whole entities.
In this chapter Darwin discusses animal instincts, where they come from, and what they do. Animal instincts are behavioral patterns that are ingrained into a creature’s existence. Migration is one such pattern. Animal instincts help creatures make the best of the traits and physical attributes that have been developed through natural selection. The one problem that Darwin has is explaining the origin of these traits. Where do they come from? Are they generational?
In another part of that chapter, Darwin addresses the lack of transitional varieties of species. He argues that since the environments required to initiate change in an organism are often in the extremes, that transitional varieties of species who did not adapt quickly enough would have died off rather quickly, and left no trace. This makes sense in the scope of natural selection. If there is a dog in a desert, and there are three varieties of the same dog – short haired, medium haired, and long haired, the long haired variety of dog will die off rather quickly. The short haired dog will survive easily because it is already well adapted to this climate. The medium haired dog may survive, and it may eventually adapt to the environment, but there are a variety of factors to consider. Perhaps the large success of the small haired dog will leave the medium haired dogs with less food, or perhaps there will be a really bad summer where it gets even hotter and most of the medium haired population, who isn’t perfectly suited for this environment, dies off? These concepts and situations are common.
In this chapter, Darwin addressed some of the weaknesses of his theory this far. One of the points that he really doesn’t have a response to is how objects such as an eye, which is so complicated, can occur in descendants of beings that don’t have eyes, nor have the material in their genome to build such complicated organs. The simple answer is that cannot occur, and by the way he writes you can tell that Darwin knows that full well. Creatures can lose eyes or eyesight by natural selection, for example, exclusively cave-dwelling creatures often go lose the faculty of vision over generations simply because they don’t need to see. However, for a creature with no eyes to slowly create such an organ is flat out impossible. However, if you factor in the theory of intelligent design, the origin for complex organs is suddenly a lot easier to understand.
So far, Darwin’s arguments in origin of species have done nothing but show observable change and speculate of the reasons for it. None of the points that he has made so far dispute creationist theory. For example, in this chapter he discusses more variations and reasons for them. He shows that organs that are more often used tend to have more variations – for example, wings on birds tend to show many variations. He also points out that sometimes species’ DNA will revert and show similar variations to that of their ancestors. For example, horses getting zebra-like stripes, or pigeons that have descended from the blue rock pigeon developing blue hues. This supports modern DNA studies, that the genome of a creature can have information molded, changed around, or even taken away, but never new information added.
In this portion of Origin of Species, Darwin discussed the survival of species, and how they can benefit or harm each other. Essentially, there’s limited space in every environment. plants and animals will always either form symbiotic relationships to survive, or take the other species’ resources/use them as resources. Darwin states that creatures are always adapting to try to stay on top of the game in this race for survival. Eventually, however, some creatures will be forced out of the environment and probably die because they did not adapt quickly enough. A question that I saw posed that relates to this is- the earth has limited resources, and the human race is using them more and more quickly. When resources begin to draw thin, how will we adapt? Will we all work together to survive, or will we begin to turn on each other for advantage in this dying world?
The chapter in Origin of Species that I just read discussed variations and introduced several other popular Darwinian theories. Darwin’s theory of variations essentially says that there can and are observably variations among species based on a great number of circumstances. I fully support this concept. There are obvious and observable examples today of variations among species. After this, Darwin proceeds to introduce the concept of natural selection, stating that individual variations are sometimes selected to reappear in later generations. I agree this concept as well, as it makes sense. Even among humans, there are recessive traits and ones traits that only appear every several generations. So far, the book has been intuitive and intelligent, albeit a difficult read due to the 18th century language used.
The next book I’m going to be starting is Charles Darwin’s Origin of Species. This book is claimed to be the origin for the concept of evolution as a whole. However, in this text Darwin presents a lot more than just his theory of evolution. This book is full of intelligent scientific observation and reason, and I look forward to reading it and seeing Darwin’s own thoughts regarding his many well-publicized theories.
In the next chapter of Walden, Thoreau extols the virtues of his move away from society. Specifically, he praises his decision to move away from the post office, because in his mind and time, the post office is the main source of communication and also obligation. How much more difficult would this social experiment have been today? The fact is incredible that by simply moving away from two things- people and the post, Thoreau can isolate himself from society. In this day and age, it’s much harder to get away from people. With the advent of cell phones, social media, and just our society becoming more and more socially oriented, means that such a move would be quite difficult to execute today.