Darwin's Postulates

Karla Hinojosa

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What are Darwin's 4 postulates?

In order for Darwin to be able to explain natural selection, Darwin said that some individuals are more "fit" than others. So Darwin broke up the concept of natural selection into 4 different criteria: variation, inheritance, differential survival, and extinction.

What do they mean?

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Variation means that individuals in a population vary in shape, size, and other traits. An example of this would be the fur in zebras. They all have stripes but they dont all have the same exact pattern of stripes. Or even in humans, we all have different heights, skin colors, hair color, or eye color. Our traits are different but we are all still the human species.


Inheritance is the traits that parents pass on to their offspring. For example tall parents tend to have tall kids. Or the fact that people look like their parents and/ or their siblings is because they come from the same parents so their traits are passed down to the next generation.

Differential Survival

Differential survival, is when there are a lot of animals from a certain species that don't survive but there are a few that do. Those that do, reproduce and pass down the traits that are necessary for survival. There are still recessive genes that are left but eventually they don't exist. For example if there are 100 squirrels, they wont all survive. But if 25 survive they will reproduce and pass down their genes that made them survive.


In some cases, there are species or offspring with certain traits that are not suited for survival. In this case the species will eventually die out and become extinct. An example of this would be dinosaurs. Dinosaurs probably became extinct because a meteor hit, and this caused the death of the species. Today it still happens there can be times when the world is hotter or colder so if a species cant keep up with these changes and adapt or evolve they will eventually die out.


Allison, L., Freeman, S., Quillin, K. (2013). Biological Science Fifth Edition. London: Pearson.

Charles Darwin (artist) [drawing] Retrieved from URL:https://upload.wikimedia.org/wikipedia/commons/a/ae/Darwin's_finches_by_Gould.jpg

Herbert Rose Barraud (Photographer)(1881)[Photograph] Retrieved from URL:https://upload.wikimedia.org/wikipedia/commons/b/bf/Charles_Darwin_photograph_by_Herbert_Rose_Barraud,_1881.jpg