Charles Darwin, an English biologist, is strongly associated with the creation of a theory of evolution. He made four main observations that led him to believe in this theory. The first was that living things generally produce more offspring than can survive due to various natural forces. This led to his second observation – that each offspring has variation from each other, which makes it an imperfect replica of its parents (Greeberger 22). These variations led to a third observation – that some variations will lead to an individual having a greater survival advantage than others (Schopf 19). The final observation is the culmination of these observations – that the individuals which have variations that are more useful in their environment will have a greater chance of survival (Schopf 19). This increased chance of survival will lead to more successful offspring ( a type of sexual selection). The overall effect of these observations led to natural selection – the production of offspring that are more adapted to their environment will likely survive longer and therefore pass on their successful traits to more offspring. This will lead to overall changes in the characteristics of a species (Greeberger 22).
The overall theory of natural selection led to Darwin’s idea that there is such a thing as “descent with modifications”. These modifications arise at random in an individual, and are what makes siblings of the same parents different from one another (Greeberger 23). These modifications may confer certain advantages to individuals within a population that help them to better engage with their environment. An example of this would be of the polar bear. A polar bear has white fur that allows it to camouflage with its environment (Wilson 25). Bears without white fur are less likely to survive because they may be targeted by predators, or unable to feed themselves as they are obvious to their prey, who can escape as soon as they are visible (Wilson 26). In terms of natural selection, the bears who have the most appropriate fur color for their environment are more likely to survive and produce a higher number of offspring. This in turn produces offspring that carry the successful traits of the parents, which has led to the evolution of the polar bear and the reason why it is adapted to its environment through descent with modifications. Other species show similar processes which show that they have adapted through time to best meet their own survival needs.
There are many reasons to believe in evolution, in my opinion. There is a lot of data that shows how different species are related to one another, and judgments can be made as to how the differences between them are associated with heritable changes related to their environment. I personally think that there are a few problems with the theory of evolution, but this is supported by some scientists (Greeberger 71). There is new information about the role of epigenetics, for example, which explains the differences between identical twins (Greeberger 71). Despite this, evolution itself (including the theory of natural selection) gives a lot of insight into how speciation (the creation of new species through heritable changes in the genes, such as the evolution of the dog from the wolf) occurs. It is also interesting because it explains how two different populations of the same species that live in two separate geographical areas can have significant differences. These differences are explained not by the species of the population, but the way that their descent with modifications has allowed them to adapt to the environment with which they interact.
I hope you found this interesting!