Darwin's Four Postulates

By: Andres Fernandez

What exactly are Darwin's Four Postulates and why are they so important? Lets find out!

1. Individual Variation - Darwin argued that there was a lot of variation within a species.

2. Inheritance - Darwin also noted that there was inheritance with a special and that offspring had similar traits and characteristics from their parents. Also that reproduction was not random.

3. Differential Survival - Darwin also noted that external factors also influenced survival.

4. Extinction - Darwin came toa conclusion that some traits from certain species are not fit for survival so in turn they would die off.

Individual Variation

The first of Darwin's postulates consists of individual variation. Darwin noted that there was a lot of variation with a species. Although the certain species was the same, there was small things that differed. Due to the time period Darwin made this informations, he was not bale to deduce why this variations occur. He did not posese the knowledge of DNA and generic variations we have today. Today we know that toots of this variations are mutations and sexual reproduction. Mutations alter a gene and therefore the next generation will have some differences. Mutations occur so that a certain species can survive to a changing environment. Sexual reproduction also causes variation because during this time, genes from both of the parents are mixed to create a slightly variated organism of the same species
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2. Inheritance

Darwin, again limited with his unfourtounate time period, figured that some of the traits of a species are passed from one generation to another trhough offspring. Darwin never managed to find out the scientific reason why but he did find the correlation between offspring and phenotypes. Today we now know that generic variations are caused by the reshuffling of genes in the offspring. Darwin could not find this out because he did not have nor the technology or the genes to know this. In this case Darwin conducted an experiment with finches, and compared their beak size. From this experiment he backed his conclusion that generic traits can be inherited.
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Differential Survival

Darwin's third postulate is a rather unfortunate. It basically states that species organisms lay more offspring than necessary and therefore some of those organisms die. The logic behind this is that there is more likelihood of survival if more offspring is produced. A good example of this is would be natural selection and how and environmental factor influences the life of a species. A heaven eating earth bugs is a perfect example of this. There are bugs of the color green and bugs of the color orange. Ravens are attracted to the green earth bug and not the orange bug. By natural selection, the orange bug is more likely to survive and pass its offspring, but, there still will be a green bug. Here is where we see the variation happening. Darwin tested this same theory when he analyzed the beak of finches before and after a natural disaster. He saw that the population of finches with the medium beak had decreased drastically since they could not adapt to the change.
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Extinction

Finally we have Darwin's fourth postulate.This postulate talks about extinction and the major key that is that the reproduction and survival of a species is not random and in fact has a logic behind it. Extinction is also part of nature and when a species is not able to adapt then the inevitable outcome is extinction. Darwin found a connection between time and extinction, and figured out that the more time passes, the more species become extinct. He figured that the more time passes, the more changes species have to adapt to. Some of this species are not able to adapt and therefore are caught out and end up extinct.
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