Darwin's Four Postulates

What can we find out?

The 4 Postulates:

(1) Every individual organism within a population will vary when it comes to their traits.

(2) The heritable genetic variation of individuals in a species due to mutation and sexual reproduction.

(3) More offspring are produced in each new generation than can possibly survive.

(4) Natural Selection - Individuals that have certain traits are more likely to survive and reproduce.

1. Every individual organism within a population will vary when it comes to their traits

Postulate One

All that this postulate is saying is that all organisms/individuals within a certain species or population have different traits and characteristics that stem from different genes which make them unique. As an example, think about the human species, each and every one of us is different in some way or another, it could be your hair, your eyes, your physicality, or anything else, but you can be sure that any person is different than another one. This means that there is always variations, and differences in traits and characteristics between individuals. There is a wide variety of characteristics and traits that can be found for any species, and in the end, that is what sets them apart.

2. The heritable genetic variation of individuals in a species due to mutation and sexual reproduction.

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Postulate 2

Individuals within populations will have different traits, some of which are heritable. This means that some of the traits and characteristics seen in individuals can be passed on to future generations. A clear example of this is how parents who both have blue eyes tend to have children with blue eyes, as is the same with brown or green eyes. We got to perform an activity/game in class in which we got to learn all about dominant and recessive genes and how they play a part in the passing on of characteristics and traits from one generation to another. A clear example that came from the game is how there was a mutation which made the bunnies fur white (and they lived in an arctic environment), this meant that these bunnies were more likely to survive and therefore more likely to pass on the white fur gene. As time went on, you would begin to see more and more bunnies have white fur, until they were a full majority, you can clearly see Darwin's second postulate playing an important role in this case.
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3. More offspring are produced in each new generation than can possibly survive.

Postulate 3

Most, if not all, species reproduce in some way or another, which means that populations are, in most cases, increasing in some way or another. What this postulate is basically trying to say is that more offspring are produced in each generation than can possibly survive due to predation, food, shelter, or other affecting factors. Take as an example a population of rabbits. Maybe, in a certain mating season, 1,000 offspring are produced, this means that 1,000 rabbits are born as a result of mating. This postulate states that the environment around them is not fitting for all of them to survive. Some of them may succumb to starvation, and others to predation, but the overall point is that no all of them will survive, even if the species is flourishing. Now, we also know that organisms are born with different characteristics, which tells us that some of these individuals/organisms are more likely to survive due to their unique/defining characteristics, which ties in perfectly with the fourth and final postulate we will look at.
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4. Natural Selection - Individuals that have certain traits are more likely to survive and reproduce.

Postulate 4

Natural selection is basically a combination of the previous postulates discussed postulates. What natural selection is basically stating is that organisms/individuals who are more suited to survive due to their fitness or characteristics will also be more likely to pass on their genes through reproduction, this is simply related to the fact that organisms without those advantageous characteristics will most likely die off before it manages to reproduce. For this postulate we can use one of the same examples we used before, that of the white and brown bunnies. If you look at an arctic environment, it is highly likely that white bunnies have a higher chance of survival than brown bunnies. So in this case, natural selection would take over and make sure that white bunnies begin to overrule the population when it comes to genes, since more of them would survive, meaning that white bunnies would pass on their genes more often than brown bunnies. So basically, if an organism has some sort of advantageous characteristic, it will survive and reproduce with greater ease than an organism without said characteristic.
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Sources


Evolution. (2015). Funk & Wagnalls New World Encyclopedia, 1p. 1. fromhttp://web.b.ebscohost.com/ehost/detail/detail?vid=4&sid=6a3d5718-34c0-4360-a7a3-2374025a90d5%40sessionmgr114&hid=107&bdata=JnNpdGU9ZWhvc3QtbGl2ZQ%3d%3d#AN=EV073800&db=funk


Woman Frantically Begs Bear To Not Eat Her Kayak; Bear Eats It Anyway. 2016. Web. 2 Aug. 2012. from http://i0.wp.com/cdn.bgr.com/2015/10/bear.jpg?w=625


WGBH Educational Foundation. "Frequently Asked Questions About Evolution". (2001). PBS Home. Retrieved from http://www.pbs.org/wgbh/evolution/library/faq/cat01.html


Wikimedia. (13 November, 2003). Genetic Variation. Retrieved January 29, 2015 from https://en.wikipedia.org/wiki/Genetic_variation