Darwinism Postulates

By: Andres Richardson

Darwin's 4 Postulates

1. Variation
2. Inheritance
3. Differential Survial
4. Extinction


The chromosomes contain the genes you inherit from your parents. There may be different forms of the same gene – called alleles. For example, for the gene that determines eye colour, you may inherit a brown allele from your mother and a blue allele from your father. In this instance, you will end up with brown eyes because brown is the dominant allele. The different forms of genes are caused by mutations (changes) in the DNA code.


Without genetic variation, some of the basic mechanisms of evolutionary change cannot operate.

There are three primary sources of genetic variation, which we will learn more about:

  1. Mutations are changes in the DNA. A single mutation can have a large effect, but in many cases, evolutionary change is based on the accumulation of many mutations.

  2. Gene flow is any movement of genes from one population to another and is an important source of genetic variation.

  3. Sex can introduce new gene combinations into a population. This genetic shuffling is another important source of genetic variation.

Differential Survival

Natural Selection is a key aspect to the genetic variation in a species. Difference in the species and genetics of an animal is key to survive. Animals that are different in a species are key to change the aspects of a species so they can adapt to the life they need. Adaptation is important to survive and natural selection will take place if animals do not adapt.


Human beings are currently causing the greatest mass extinction of species since the extinction of the dinosaurs 65 million years ago. If present trends continue one half of all species of life on earth will be extinct in less than 100 years, as a result of habitat destruction, pollution, invasive species, and climate change. Extinction is the end of a whole species.


Berkley. "Genetic Variation." Genetic Variation. Berkley, 24 Oct. 2010. Web. 08 Apr. 2016.

Couples, F. (2001, September 21). What is inheritance? - Definition from WhatIs.com. Retrieved April 08, 2016

Paper, W. (2010, August 24). The Current Mass Extinction:. Retrieved April 08, 2016,

Riggs, R. (2009, May 28). Result Filters. Retrieved April 08, 2016,