Darwin's Postulates

By: Paola Gutierrez

What are they?

In 1859, Charles Darwin introduced The Theory of Evolution to the world. This theory was made up of four postulates that Darwin thought of to be the most important when talking about a species and it's evolution. Darwin's ideas are based on this theory that life evolves by natural selection. Darwin came to question the evolution of species when he noticed different dog breeds and pigeons with different characteristics, this led him to believe that all species evolve. Below I will talk about Darwin's four postulates and what they mean.

Postulate #1: Variation

The first postulate states that there is variation among individuals. This means that each individual is unique within its population. Although they may look similar on the outside, in the inside they can be very different. For example, two twins may look identical but they still hold variation within their DNA and other parts of their bodies, the same goes for different animal species. There will be variability in nearly all traits that each species posses because of their genetic differences. Variation can occur in a number of ways like: mutations, DNA damage, DNA replications, cell division and sexual reproduction.

Postulate #2: Inheritance

The second postulate states that some of the variation is heritable and this causes offsprings to look like their parents. This is the tendency of offspring to resemble their parents. Although Darwin did not have understanding of DNA of genes back in 1856, he did know that in order for selection to occur, variation must be transmitted from parent to offspring. This is because variation occurs in the difference of genes and genes are passed down from generation to generation.

Postulate #3: Differential Survival

The third postulate states that individuals vary in their success at surviving or reproducing. This means that in each generation there are more offspring produced than can survive, which causes some to survive and leave offspring for next generations and some that don't. There will be variation between individuals and how they reproduce and this will affect future generations. Some offspring will not be able to survive until their reproductive age because of different factors like predation and food supply.

Postulate #4: Extinction

The fourth postulate talks about how species survive and/or reproduce is nonrandom. It is nonrandom because their survival age and their reproduction status will be affected by the traits that they posses. Some traits are not suited to survival and those with them will die out. This can be compared to the saying, "survival of the fittest" because only the individuals with the greatest fitness will be able to survive and reproduce. For example, individuals that have genes that have evolved to a certain point in order to make it easier to survive in a certain environment are more likely to survive. When individuals posses these traits are better adapted to their environment than those who don't. For example white bunnies are more prone to survive in the Arctic than brown bunnies because they can camouflage with the snow and vice-versa for brown bunnies in the equator.


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