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The Literary Genre of Speculative Evolution

The Literary Genre of Speculative Evolution

Speculative Evolution is a subgenre of fiction. The foundation of this literary genre comes from Charles Darwin and Alfred Russel Wallace’s theory of evolution. Their theory stipulates that living organisms on this planet are in a constant state of survival. Because of this, they change their shape, capabilities, and behavior to better compete and thrive in the environment. Therefore, the genre’s peculiarities lie in the hypothetical scenarios of evolution.

World Building

Aliens from Discovery Channel's Alien Planet (2003). Photo Credit:
Aliens from Discovery Channel’s Alien Planet (2003). Photo Credit:

The literary genre’s specialty is world-building. Authors from this genre create scenarios by changing environmental conditions. As such, they could create worlds that diverge from the realities of our world. Common among the worlds they create are alien planets. But, authors do sometimes use Earth as their setting. Authors use these worlds to speculate what unique flora and fauna might evolve from alien planets.


Here authors use the study of Botany to justify why their floras act and look the way they do. As such, Earth floras commonly use green pigmentation to absorb light from the sun. This happens on our planet because green is the most efficient color for plants on Earth to absorb sunlight.

Alien Flora by Henrik Ågren. Photo Credit:
Alien Flora by Henrik Ågren. Photo Credit:

As such, the literary genre creates fictional planets with different characteristics. Repercussion to such change led to their plant-like photosynthetic organisms favoring a different color pigmentation. The changes follow the evolutionary process of living organisms changing and adapting to their surroundings. Due to the changes, the flora could have red, violent, or whatever color pigmentation. In addition, organisms could have different cellular and body structures to help them survive on the planet. Furthermore, authors can use these changes to evolve their flora sentients like animals on Earth.


Speculative Evolution goes beyond the flora. Commonly, the literary genre also speculates what fauna could have evolved on the planet. Thus, authors commonly use the field of study called zoology in their literature. They can create realistic alien fauna by following the footsteps of real-life zoologists. Therefore, authors imagine their fauna as creatures specifically adapted to live on the planet they created.

Pterosapiens from All Tomorrows. Photo Credit:
Pterosapiens from All Tomorrows. Photo Credit:

A planet with low gravity is a frequent setting used in speculative evolution. Authors will use this characteristic to speculate how faunas evolve. To help the authors with the speculation they will use the science of zoology. As such, authors would speculate that faunas might evolve to be larger creatures than on Earth.

Alien faunas in this environment can grow taller because there is less force pushing down on the creatures. Or maybe most faunas evolved to be avian due to low gravity. Next, the author must answer the question of how one would faunas’ eat with low gravity. Then authors must discuss how they live in their low-gravity habitats. Lastly, elaborate on how they interact with each other. All of this is important to build a comprehensive Speculative Evolution.

Spectrum of Speculation


We categorize Speculative Evolution in a spectrum from Earth-like to Alien-like. Elements of the literary genre in mainstream science fiction conform to Earth-like organisms. Authors use Earth-like evolutionary speculation to make the alien relatable. Aliens depicted in this spectrum are similar to animals on Earth. Thus, making the aliens more appealing to the general public.

Evolutionary Tree of Aliens in James Cameron's Avatar. Proto Credit: YouTuber TREY the Explainer
Evolutionary Tree of Aliens in James Cameron’s Avatar. Proto Credit: YouTuber TREY the Explainer

The 2009’s film Avatar by James Cameron is a perfect example of this. Cameron based his aliens to have commonality with lifeforms on Earth. Because of this, the Na’vi aliens are bipedal humanoids. While the flora and fauna of the planet are based on creatures that exist on Earth. Cameron also took inspiration from Earth’s flora and fauna to build Pandora’s ecosystem. The planet’s flora is green and has bioluminescence similar to Earth’s flora. While Cameron’s alien fauna are based on Earth animals like horses, wolves, pterosaurs, rhinos, and primates. In addition, he rooted their behavior on Earth’s animals. As such, people who have watched Avatar are not horrified when seeing Pandora’s creatures.

Easter Saber Tooth Thanator, fan-art from Avatar (2009) by Alfonso de la Torre. Photo Credit:
Easter Saber Tooth Thanator, fan-art from Avatar (2009) by Alfonso de la Torre. Photo Credit:


While for the other side of the literary genre spectrum we have the Alien-like. Man After Man by Dougal Dixon is a case example of this. Man After Man is a book that explores the concept of human evolution in the future. Dixon’s depiction of humanity is unsightly and horrific. This is because evolution in space does not conform to evolution on Earth.

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Book cover of Man after Man by Dougal Dixon. Photo Credit:
Book cover of Man after Man by Dougal Dixon. Photo Credit:

Our bodies evolved to live on Earth. Because of this, our bodies must evolve to survive outside Earth. Dixon depicts these changes as adaptation through genetic modification. Thus, future humans will no longer look like humans in the present.

Image of a Vacuumorp from Man after Man. Photo Credit:
Image of a Vacuumorp from Man after Man. Photo Credit:

Vacuumorph is new human species in the book. To survive in space, Dixon describes people using genetically modified to alter their bodies to survive in space. Because of this, they form into an infertile three-lunged, crustacean-like human. The crustacean-like feature is to protect their internal organs from cosmic radiation and the vacuum of space. While the three lungs are to help them stay in space for long periods. Sadly, because of this change, their bodies could not survive in Earth’s atmosphere. Here you can see the influence of Darwin and Wallace. Because changes in the environment led human beings to become the Vacuumorph.

Illustration of a Vacuumorph's anatomy. Photo Credit:
Illustration of a Vacuumorph’s anatomy. Photo Credit:

Authors use this form of Speculative Evolution as a tool of horror. The exitance of the Vacuumorph is to expose the audience to the unsightly reality of evolution. In addition, the authors use this to demonstrate how deadly space is. And to show that our present human bodies are not capable of surviving in space.


The genre of Speculative Evolution is not popular. This is because the genre has grotesque depictions and unsettling themes. But beyond this, the literary genre is important because it teaches us about biology. Organisms change overtime to adapt to their environment.

In addition, the genre provides a medium for asking hard questions about humanity’s future. For example, how should humanity react if we finally found extraterrestrial life? And due to their alien nature would we see their life as equal to our own? Lastly, it asks us about the ethical dilemma of genetic modification. At what point do draw the last when artificially augmenting our bodies?

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