Darwin's Postulates

Darwin's way of Explaining Natural Selection

The first postulate: Variation

Within spices there is variability in size, color and other physical and physiological aspects. Some of this variability can be:
  • Differences between cells
  • Differences between organisms
  • Caused by genetic or environmental

This can be proved with Darwin's Finches in the Galapagos islands, each bird adapted to its environment and have developed different beaks according to their needs.

The second postulate: Inheritance

Some of the variation is heritable, we obtain features inherited from parents through genes. Things we may inherit through our parents can be:
  • Eye Color
  • Size
  • Skin color
An example of this are humans. You can see how a child may look similar to his parents or brothers yet they are not identical. This is thanks to the variability in genes and alleles. In this case you see how David Beckham's son has similar features to the ones of his father, this features are all inherited from his parents. In this case the majority of David Beckham's alleles are the dominant making his son so similar to him.

The third postulate: Population expansion

The only way a species can survive is by reproducing themselves, but since there are limited resources species have to fight for them if they want to survive. The strong and fit are the ones who are able survive because of the features they have that allow them to win against rival species. An example top predators like:
  • Great white sharks
  • Humans
  • Cheetahs
All of these creatures have the ability to win over resources without a problem and with it easily reproduce to increase their respective populations. Sharks use their strong teeth, humans use their brains to make tools and cheetahs use their speed. Many species have a special feature that allow them to overcome rivals, but not all are able to succeed and remain in this planet.

The fourth postulate: Non-Random Survival and Reproduction

It is not by chance that certain species are able to survive. The strong and fittest species are the "selected ones" through natural selection. We can see this in many of the species which are fit for the environment and able to adapt.

An example of this fourth postulate are primates, there is a great variety of species which evolved from the primates like:
  • Neanderthal

  • Homo Sapiens Sapiens (Humans)
  • Australopithecus
But the only species from this example who has been able survive, adapt and remain in this earth is the Homo Sapiens Sapiens. This species has exponentially reproduced throughout the last centuries, while the others have not been able to adapt and have gone extinct. There are now over 7,000,000,000 Homo Sapiens Sapiens on earth. It is not by chance, Homo Sapiens Sapiens have been able to adapt to their environment and through natural selection have been able to survive the changing conditions of this world.


Buffalo State. (n.d.). Chapter 3. Darwinian Natural Selection. Buffalo State. Retrieved April 5, 2016 from <http://faculty.buffalostate.edu/penaloj/bio405/outline3.html>.

Charleswood, B. (2009, November 1). Darwin and Genetics | Genetics. Retrieved April 04, 2016, from http://www.genetics.org/content/183/3/757

University of Evansville faculty. (n.d.). Natural Selection. University of Evansville. Retrieved April 5, 2016 from <http://faculty.evansville.edu/de3/b32003/lecture%20summaries/selection.pdf>.