Darwin's Four Postulates

Guillermo Bailleres


Darwin stated that individuals within a population are variable. But what is variation? Well, variation is commonly used in genetics and refers to individuals or groups of a certain type of species that have slightly different characteristics. For example, in humans we can distinguish variation very easily. We all share basically the same functions, however, there are different types of skin color, hair color, or even slanted eyes, etc.


Darwin also stated that variations are heritable. By this he meant that if a certain organism had different characteristics from its species, this organism could pass down his unique characteristics down to its children.

Differential Survival

Darwin believed in natural selection. This is the way in which species evolve or adapt to be able to survive their surroundings. When an organism is born with different traits than the rest of their species their ability to survive with this traits will determine if they will be able to reproduce and pass down their genes. However, many times their different genes can get them killed. Their efficiency will determine if they are able to pass down this genes being therefore natural selection.


Darwin was able to notice that extinction of species have occurred continuously throughout the history of life. He discovered that extinction is caused by the failure of the ability of a species to be able to survive their surroundings or be able to survive against any type of competition. When a species loses the ability to do so it will soon lead to the species extinction.


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