Darwin's 4 Postulates

Variation, Inheritance, Differential Survival & Population

Alejandro Torre

Charles Darwin: One of the Best

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Charles Darwin was born in the small merchant town of Shrewsbury, England, on February 12, 1809. Because his father and grandfather were recognized scientists, Charles had a long line of successful experts. Darwin came from a wealthy family, who gave him the opportunity to study abroad, in one of the finest schools of the time: Cambridge. Charles was always more inclined into studying the nature in history, it's impacts, how everything has changed, etc. His curiosities led him to expose his Theory of Evolution, arguing that similarities among species all over the globe, had gradually developed from common ancestors. He officially presented his theory in 1858, and one year later, he published he most famous book of all: On the Origin of Species by Means of Natural Selection. Darwin died in his home, in 1882, with a remarkable career, that makes him one of the most recognized scientists of all time.

His 4 Principles of Natural Selection


Some traits are consistently passed on from parent to offspring. Such traits are heritable, other traits are strongly influenced by environmental conditions and show weak heritability.

Differences are also inheritable (variation). Could be passed down from generation to generation. Although some traits are constant from each generation, they could vary.

High Rate of Population Growth (Survival of the Fittest)

Most populations have more offspring each year than local resources can support leading to a struggle for existence. Each generation experiences substantial mortality.

In order to reproduce, humans must be able to be fit, to survive (Differential Survival). Qualities that help you survive may include: being smarter (brains), being physically fit for your environment, being ready, etc.

Darwin argued that population growth depended on this, on our ability to adapt to a given environment, to our community, and being able to act upon.

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Organisms (within populations) exhibit individual variation in appearance and behavior. These variations may involve body size, hair color, facial markings, voice properties, or number of offspring. On the other hand, some traits show little to no variation among individuals - for example, number of eyes in vertebrates.

The idea that there are differences within a same family. Traits such as inheriting diseases, personality, physical traits (hair color, eye color, ears, nose, etc.), arm length, etc., are all different within each individual.

Differences: They exist naturally within our environment, they are also inheritable. They can be passed down from generation to generation. Darwin was one of the first scientists to actually believe that differences were natural, and people didn't necessarily choose to be certain ways.

Differential Survival (Selective Pressure)

Individuals possessing traits well suited for the struggle for local resources will survive more and reproduce more than others and thus contribute more offspring to the next generation.

The idea that population can exceed resources. The idea of selective pressure comes in here, those that have what it takes to get to the resources, will survive.

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12.2.2 Darwin's Principles of Natural Selection


Adams, D. (2012, March 2). Intro to Charles Darwin . Retrieved April 6, 2016.

Bradford, S. (2014, February 3). Natural Selection. Postulates. Retrieved April 7, 2016.

Freeman, D. (2012, November 26). Darwin's Theories. Retrieved April 7, 2016.

Hilton, T.Y (2015, November 20). Darwin: How He Came To Be. Retrieved April 6, 2016.

Johnson, C. (2006, August 3). Darwin's 4 Postulates. Retrieved April 7, 2016.