By: Daniela Cantu
Charles Darwin believed that trait selection in breeding can occur naturally. In order for this to be true, four things had to be present. These are known as Darwin's Four Postulates of Natural Selection.
There is a lot of variety within a species. A species can have different traits or phenotypes. If variation did not exist, there would be nothing for the selection to act upon and therefore, the phenotypes wouldn't change with the years. That being said, evolution would not be able to take place.
Offspring look like their parents. This postulate is about how the more dominant phenotypic traits have to be inherited or passed on to the next generation. Although it was Darwin who first came up with this idea, he could never figure out how the genes were inherited. It wasn't until 50 years after Darwin's death that the work of Gregor Mendel provided scientists with a combination of both Darwin's and Mendel's work called, "The Modern Synthesis." This gave scientists all the knowledge they needed in order to understand how genes were passed on.
External conditions can affect survival. In every generation, not all offspring can survive, and survival is not random. There is a reason behind that. Some organisms are born with more advantageous traits than others. These organisms are the ones that tend to adapt easier to the environment and therefore hold a higher chance of survival than the rest. And these organisms are the ones that get to reproduce. This is literally the concept behind the phrase: "survival of the fittest."
Duong, J. (2014). Darwin's Postulates. Retrieved April 5, 2016.
Gardonis, C. (November 26, 2015). Survival of the Fittest. Retrieved April 7, 2016.
Darwin, C. (1904). The Origin of Species. Retrieved April 7, 2016.