Darwin's 4 Postulates of Evolution

Marcelo Sáenz

Charles Darwin

Charles Darwin is known worldwide for his contribution for evolutionary theory. There are four postulates Darwin made for his theory. After a long trip around South America, he arrived at the Galapagos Islands and made a lot of discoveries which he then wrote about in his book "On the Origin of Species".

The Four Postulates

Heritable Variation

The first postulate Darwin made states that "the individual organisms that make up a population vary in traits they possess, such as their size and shape." This means that every new generation of a certain species has different traits from their parents. These changes can be either advantageous for the species or they could be insignificant.


The second postulate Darwin made states that "some of the trait differences are heritable, meaning that they are passed on to offspring." The different traits that cause variation in a species are inherited, which is why over a long period of time species begin to evolve and have different characteristics that can help them cope with new environmental conditions.


The third postulate Darwin made states that "in each generation, many more offspring are produced than can possibly survive." Because of this only some individuals will live long enough to produce more offspring and of these, some will produce more than others. This creates competition within a species in order for the individual organism to survive and continue on with its life and reproduce again to create even more offspring who will then have to face the same challenge.

Survival of the Fittest

The fourth postulate Darwin made states that "the subset of individuals that survive best and produce the most offspring is not a random sample of the population." Instead, individuals with certain heritable traits are the ones that are more likely to survive and reproduce. When an individual with certain heritable characteristics produces more offspring than another one with different heritable characteristics it is called natural selection since the number of offspring is selected naturally by the environment.


Allison, L., Black, M., Freeman, S., Monroe, J., Quillin, K., Podgorski, G., Taylor, E. (2014). Biological Science.(Fifth Edition). Pearson.

Northwestern University. (2014). Competition for Limited Resources. Retrieved April 5, 2016, fromhttp://modelsim.tech.northwestern.edu/readings/popbio/PopBio-Reading3.1-Competiton for Resources.pdf