Understanding evolutionary psychology (for beginners)

Evolutionary psychology, as the name suggests, is the application of the principles of evolutionary theory to psychology. Before you can understand how evolutionary theory can be applied to human behaviour, you need to first have a firm grasp on evolutionary theory itself.

Theory of evolution 

It’s the year 2500 A.D. and mankind is on the verge of extinction, thanks to the destruction of the environment and persistent global warfare. There are only about a hundred humans left on the planet.



Fortunately, due to the advancement of space travel, humans have successfully found an earth-like planet with earth-like conditions that are conducive to life in a nearby galaxy. This planet- named Earthy, is their only hope for the continuation of their species.

A spacecraft takes these last remaining humans and lands them safely on Earthy. These last remaining humans consist of an equal number of males and females who look pretty much like you and me, although the laziness induced by hundreds of years of technology has sort of weakened their muscles.



Other than that, the first human inhabitants on Earthy look pretty similar as far as their physical features are concerned…
first humans on Earthy
Prototypes of first humans on Earthy. Their bodies are average sized and with average muscular strength.

Now the conditions on Earthy, though conducive to life, weren’t exactly similar to the now dying earth. For instance, only one tree grew on Earthy- a 12 ft tall tree that bore triangular, pink fruits only at its top. This was the only edible food for humans on this new planet. There was no sign of any small animals that they could hunt.




Initially, the food that they’d brought from earth had kept them together but as soon as they ran out of it they broke into smaller groups and tried to occupy areas where that tall tree with pink fruits grew in abundance. 

They mated with one another, had children who had their own children. They were slowly populating Earthy and their only source of food was this strange tall tree with its strange pink fruit at the top.



This tree, although it grew abundantly on Earthy, was literally un-climbable because it had some kind of grease on its trunk. The only way to obtain its fruit was to throw rocks at it with great force or jump high enough to grab it.



When the first humans came to Earthy and mated with one another, their children weren’t all the same, as normally happens in sexual reproduction. Some were tall, some short, some had long limbs, some were well-built, some were very thin, and so on.



In sexual reproduction, the offspring are slightly different from the parents due to genetic mutations. Now, the offspring that successfully reproduces will pass on its genetic make-up to the future generations. 


Often, the reproductive success of an organism is heavily dependent on its ability to obtain food. On Earthy, obtaining food was difficult and only those humans who had the genetic mutations that helped them attain food could survive and reproduce and pass on their genes to the next generation.

In other words, due to their genetic make-up, the first children on Earthy were either well-suited or ill-suited to obtain the fruit from the tall trees of Earthy.

For example, those who were taller were better able to procure food when they grew up. Same is true for those who had long limbs, were strong enough to throw rocks with great force and were athletic enough to jump high enough to grab and pluck out the pink fruit. 

On the contrary, those who were short, thin, weak and un-athletic faced problems in attaining food and hence were less successful reproductively.



Over time, as expected, the number of individuals having physical features that aided their ability to procure food and thus reproduce increased in the population. The ones who were ill-suited to procure food and reproduce kept on decreased in number till they were totally wiped out from the population.

After a few thousand years, Earthy was home to only humans who were tall, athletic and endowed with really long limbs- very well suited to attain food from the tall tree. 

evolution of humans on Earthy
After a few thousand years, Earthy was home to only tall, long-limbed, muscular and athletic humans.


Anyone who visits Earthy today won’t have a clue that a few thousand years ago, the first humans that landed on this planet were not as diverse as they are today and looked pretty much the same physically.


This is evolution. This is how complex life forms evolve from simple life forms. Of course, the example that I just gave you is in many ways oversimplified and silly but it lucidly explains how evolution works.

Our earth is a thousand times more complex than Earthy. There are thousands of factors that have shaped the evolution of the millions of species that live on earth today.

All the complex organisms that you see around you are the ones that possess advantageous mutations that enabled them to survive and reproduce in their respective environment. Those who couldn’t were wiped out.



On Earthy, it took a few thousand years to achieve a significant degree of complexity. On Earth, what you see around you took millions and millions of years to get that way. Hence the incredible complexity and variety of the many species that inhabit the earth today.

Evolutionary adaptations



The physical manifestation of a genetic mutation that aids survival and reproduction is called adaptation. An adaptation is simply a property of an organism that aids its survival and reproduction. For example, the ability of an animal to camouflage with its environment and protect itself from predation is an adaptation.



If an adaptation aids survival, it is said to be the result of natural selection. Properties that have survival value will be passed on to the next generation. For example, the sharp vision of an eagle is an adaptation that enables it to locate prey from afar.



If an adaptation helps with reproductive success, it is said to be the result of sexual selection. When choosing a mate, an organism will select only that individual who has desirable traits. For example, male peacocks with large, beautiful feathers are preferred by females even though such a feature has little or no survival value.



Natural and sexual selection can sometimes overlap. If an adaptation has both survival value and makes an organism a desirable mate, it will be selected by both natural and sexual selection, to be passed on to future generations.



Where does psychology fit in all this?



Now the cool thing about adaptations is that they can not only be physical but also psychological!

The psychological mechanisms that aid an organism’s survival and reproduction are genetically transmitted adaptations that manifest not as physical features, but as behavioural mechanisms. 



In other words, your mind contains behavioural programs that are designed by evolution to ensure your survival and reproductive success.

Evolutionary psychology focuses on these evolved psychological mechanisms and is the most fascinating, all-encompassing field of psychology. It explains almost all of our behaviours.

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