Darwin uses several examples in his argument of evolution through natural selection. Some of his arguments, which he lists on the last page (513) include growth with reproduction, inheritance, variability, ratio of increase, struggle for life, divergence of character and extinction. Through time, even with little evidence from the geological record, it is clear that life is constantly changing. Darwin tries to prove this by showing the readers that these changes are so small and minute that they are hardly discernable. Just because we can’t see these changes doesn’t mean they aren’t happening. He discusses that competition between species as a driving force for these changes. He also discusses why there might not be fossil evidence of changes or variations between species. Even though we can gain a lot from looking at the geologic record, there are certain aspects of life that just haven’t been preserved. I like how Darwin mentions at the end that we shouldn’t use organic change within the geologic record to measure time. These changes could have happened rapidly because of environmental changes or new competition between species.
To me, the most convincing part of his arguments was variability. Species that underwent extreme migration or environmental changes seem to have the most variability. He talks about how species of the Galapagos islands have a striking resemblance to the animals and plants found on the American mainland and the same for Cape de Verde and the African mainland. Different foreign competitors and differing environments ultimately is what helped these species live and thrive and evolve into what they have become today. “It is a rule of high generality that the inhabitants of each area are related to the inhabitants of the nearest source whence immigrants might have been derived.” (Pg. 499) I also really liked that Darwin talks about man’s role in variability and that we do not directly produce it but unintentionally we can expose plants and animals to new conditions, which in turn might force them to change.
Hi Mandy!
I like your concluding remark about where Darwin posits that “man’s role in variability” can alter the conditions of life on Earth, forcing them to change. It is interesting, and mildly depressing to view this through the lens of what we have learned so far in this course, where we have learned how through means such as industry we have changed the world and the ecosystems inside of it faster than would ever occur in nature, excluding events such as supervolcanoe eruptions. Basically, though our powers of technology and industry, we have the ability and predisposition to change the environment, often in a negative way, faster than life on Earth can adapt to it. We are forcing them to change, but they cannot adapt to the new conditions fast enough.
I totally agree with you that variability is the biggest part of evolution. Species have to be able to adapt to their environment to survive, which explains why species are variable between their genus. Whether it be migration or some other type of environmental change, they have had to adapt. I too really like that Darwin talks about mankind not directly affecting but rather unintentionally exposing organisms to different environments. The best example of this happening that I can think of would be wheat. Wheat has adapted to the point where it can grow all over the world, and humans are the reason for that.
I personally really struggled with this weeks readings. Some of Darwin’s points I understood, but there were some that you talked about that I completely missed while reading the chapter. I also found Darwin’s take on domestication and human’s role in variability interesting. I didn’t think of the effects we had by changing organisms around us and what it forced organic life to do. Of course, it’s pretty straight forward that we change plants in ways that would better suit ourselves, but I never thought about how it would also force plants to adapt to those very changes in order to continue to thrive. Overall, this was a very nice piece that also helped me with my understanding of part of the readings.
Darwin used compelling arguments that tried to prove that evolution existed. I admit it was hard to put myself in a position that others would have been in after reading this for the first time. I was always learning about Darwin and his five-year journey throughout elementary school. I didn’t have to try hard to agree with his findings, although some of them might not be completely true. I really liked when Darwin talks about humans having an impact on the environment. When this literature was published, we had little effect on climate change and most of our environmental impacts on the species had to do with unintentional exposure to bacteria or traveling across the lands. I think the main thing early humans had an impact on was wheat and where it grew across the globe. I think humans are directly responsible for the spread of that resource. Overall I thought the read was a little dry in places, but nevertheless, important and a good topic to have knowledge on.
Hello!
I was surprised to see that the most convincing part for you was variability. I had a hard time understanding how variability might play a role in evolution by natural selection so I couldn’t see it like that but I like how you explained it in more simple terms. It made more sense to me. I also like that he talked about mans role in it though and how what we do can force plants and animals to have to adapt to different environments.
Thanks for writing this in easy to read english as the original text itself was hard for me to read. I especially like how you mention how Darwin observes how humans expose certain species to new conditions which cause variation in animals. I never thought of it like that, but when I look at my lab with his webbed feet and water resistant coat of fur it starts to make sense to me. I would like to see a study produced of the different variations of animals humans have created by unintentionally exposing animals to new conditions. It would also be cool to see a chart of how the different breeds of dogs evolved into the breeds we have today. In case you have not noticed I am a huge dog person.
Great post! I agree that one of Darwin’s most interesting points is that humans will inevitably have an effect on a species’ ability to adapt. I’d say that his thoughts on this were surprising for such an early time in the history of science, but this class has taught me that scientists have been studying man’s effects on the environment long before when it is widely thought thought to be. I think you’re last sentence really sums up the entire problem of human existence in comparison to the earth, we are changing to face for it to keep up.