Darwin's Four Postulates

By Juan Pablo Riojas

1) Species can increase numerically

This postulate explains that all species actually have the potential to increase in number. If enough reproduction occurs, or there is less natural selection, the species may increase by number in big sizes.

2) Genetic variation will exist within species because of genetic mutations and sexual reproduction

WIthin a population of a species, many of them will be different from each other. All of this will be due to the fact that genes are different in each individual because of mutations and inheritance from the sexual reproduction their parents had.

3) There is more reproducing and offspring than number that survive

Overproduction is what is being discussed here. From generation to generation, in almost every given species, they tend to reproduce more than the ones that survive. This is true for all species according to Charles Darwin, which formed this postulate

4) Survival of the Fittest

In a given species, only the ones that are best adapted to the environment will thrive, and eventually evolve to be able to thrive even better. This means that the fittest will survive and the species will become very fit as a whole.


Cena, J. (1999, March/April). Introduction to Ecological Genetics. Retrieved April 08, 2016, from http://ib.berkeley.edu/courses/ib162/Week1.htm

Richardson, R. (2001, December 29). Ch 3. Darwinian Natural Selection. Retrieved April 08, 2016, from http://faculty.buffalostate.edu/penaloj/bio405/outline3.html

Torres, M. (1995, April/May). Darwins Second Idea Natural Selection. Retrieved April 08, 2016, from http://public.wsu.edu/~dybdahl/EvolLect4-06.htm