Juice wrote: ↑October 15th, 2009, 4:32 pm
First let us provide a specific definition to the theory of "Natural Selection" before trying to apply it to a fossil record or confusing it with what is known about the process of genetic mutability and transference.
Charles Darwin is the originator of the theory of natural selection which has its premise based on aspects of animal husbandry were animals of the same species are bred in order to produce more desirable and advantageous traits. Horses, for instance, would be bred for specific utility: race horses for racing, pack horses for carrying and plow horses for plowing. By this example we must understand that Darwin's original theory, based on the primitive observations at the time has transformed from his original concept into the completely different definition of today. Before providing criticisms or rebuttals to the overall theory we must understand what the difference is between the classic and the modern representations of natural selection and the reasons for that metamorphosis.
Charles Lyell laid the groundwork for Darwin's theory through his observations of geology and his theory of "uniformatarianism" which fundamentally stated that the earth is very old and transformed by current observable phenomenon, volcanoes and earthquakes. So Darwin's theory had to fit with that concept of a very old earth.
We have to understand that Darwin, although he provides limited observations for his theory, was very much motivated by his own reasoning and the works and observations of others in his day. I mention this so that we can understand that Darwin really did not have any real empirical evidence for his theory and that it is basically a thought exercise for him.
In reality it can be argued that Darwin actually got the impetus to publish his seminal work "Origin of Species" as a result of reading a paper written by naturalist Alfred Russel Wallace. Not to give credit to Russel, but only to invite inquiry into the evolution of evolution theory.
The four main parts of Darwin's theory;
1. Organisms have changed over time, and the ones living today are different from those that lived in the past. Furthermore, many organisms that once lived are now extinct. The world is not constant, but changing. The fossil record provided ample evidence for this view.
2. All organisms are derived from common ancestors by a process of branching. Over time, populations split into different species, which are related because they are descended from a common ancestor. Thus, if one goes far enough back in time, any pair of organisms has a common ancestor. This explained the similarities of organisms that were classified together -- they were similar because of shared traits inherited from their common ancestor. It also explained why similar species tended to occur in the same geographic region.
3. Change is gradual and slow, taking place over a long time. This was supported by the fossil record, and was consistent with the fact that no naturalist had observed the sudden appearance of a new species.
4.
The mechanism of evolutionary change was natural selection. This was the most important and revolutionary part of Darwin's theory, and it deserves to be considered in greater detail.
*One of the prime motives for all species is to reproduce and survive. When species do this they tend to produce more offspring than the environment can support.
*The lack of resources to nourish these individuals places pressure on the size of the species population, and the lack of resources means increased competition and as a consequence, some organisms will not survive.
*The organisms who die as a consequence of this competition were not totally random,
Darwin found that those organisms more suited to their environment were more likely to survive.
*This resulted in the well known phrase
survival of the fittest, where the organisms most suited to their environment had more chance of survival if the species falls upon hard times. (This phrase if often associated with Darwin, though on closer inspection Herbert Spencer puts the phrase in a more accurate historical context.)
*Those organisms who are better suited to their environment exhibit desirable characteristics.
Consider that Darwin had no idea of inherited traits and had no clue of genes as the driver of change. In fact Darwin actually regretted using the term "Natural Selection", preferring "Natural Preservation"
As we will see the concept of Natural Selection had to be modified due to the discovery of inherited traits and subsequently "genes".