The Science of Aliens Part One

I have been reading the Science of Aliens  by Clifford Pickover, which has been incredibly fascinating. It included a lot of pictures to help supplement the discussion.  Since I have my world-building series about creating worlds for your stories, this seemed to be a good supplement to that series.  Now we need aliens to populate the worlds you’ve created.  Thus, I have decided to start a new world-building series that discusses aliens.  I’ll use this book as one of my references — my main reference, though I will reference other useful materials as necessary, so if you’d like to read along, you can find this book for fairly cheap at Amazon.

Today, I’ll mostly discuss evolution and other basics Mr. Pickover covers in Chapter 1: What Aliens Look Like.  Consider this the first part in this series.

In order to create an alien species, we need to understand the basics of evolution.  Evolution is a process helps species alter their characteristics to better suit their environments and optimize their survival.  Evolution is about problem-solving, and various traits is nature’s ways of solving problems that crop up as species adjust to various environments.  Here Mr. Pickover explains the concept of convergent evolution (a useful concept to keep in mind when creating aliens):

Evolution on Earth tells us a lot about possible alien shapes. Although every detail must be different, there are patterns of general problems, and common solutions to those problems, that would apply to life on alien worlds.   In the course of Earth’s history, whenever lifeforms have had a problem to solve, they solved it in remarkably similar ways.  For example, three very unrelated animals — a dolphin (a mammal), a salmon (a fish), and an ichthyosaur (an extinct reptile) – have all swum in coastal waters darting about in search of small fish to eat.  These three creatures have very little to do with one another biochemically, genetically, or evolutionarily, yet they all have a similar look. On first glance, they look like nothing more than living, breathing, torpedoes.  Although they are biologically quite different, they have all evolved streamlined bodies to help them travel quickly through the water.  This is an example of convergent evolution, and we might expect aquatic aliens that feed on smaller, quick-moving aliens also to have similarly streamlined bodies.  ~ Chapter 1; Page 16 of hardback copy of Science of Aliens 

Convergent evolution is incredibly useful to remember for often when one solution works for that particular type of environment, then it’s fairly given that other species may end up evolving that solution. This makes alien creation a trifle easier, especially considering that there’s really an infinite set of possibilities for how a species can evolve — depending on the numerous factors within one’s environment and the species itself.

Another aspect to consider is symmetry.  As defined by Mr. Pickover:

To a biologist, symmetry refers to the orderly repetition of the parts in an animal or plant. Often symmetry refers to the position of body parts on opposite sides of a dividing line or distributed around a central point or axis.

The use of this idea will be very beneficial for species development. For example, bilateral symmetry is when one plane of symmetry divides a creature into symmetrical halves. A good example of this idea is humans; if you were to slice a human in half, you would get two very similar pieces.  (Not that you ever should, and so not endorsing trying that at home!)  This is a characteristic of a vast assortment of animals, including birds, mammals, insects, amphibians, reptiles, fishes, and some crustaceans.  Aquatic creatures in particular may tend toward bilateral symmetry because it offers a fairly efficient way to create a streamlined, muscular body, which allows the animal to more efficiently catch food and fleeing predators.

Another possible symmetry is radial symmetry.  As defined by Mr. Pickover:

In radial symmetry, the body has the general form of a cylinder or bowl with a central axis from which the body parts radiate, or along which they are arranged in a regular fashion.

Starfish, urchins, and jellyfish are all great examples of radial symmetry.  Also, note that they are slower moving than those with bilateral symmetry.  However, despite this slower pace, they have other interesting evolutionary features that allow them advantages in other areas, due to how they evolved in their particular niche of ocean.  Symmetries is useful, but remember, it doesn’t necessarily give you clues as to how the anatomical insides of an alien could be.  For example, just because an alien may have radial symmetry similar to a starfish, doesn’t mean their anatomical insides are exactly the same. Depending on the environment and the problems encountered therein, evolution may have evolved a slightly different take on the insides to create a more efficient way for that alien to survive.  This i n turn allows for a more varied set of possibilities, for aliens.  You can decide on a basic symmetrical form, but how the anatomy is constructed will differ based on various external and internal factors.

Symmetry is most useful in constructing the external form of an alien, but it doesn’t necessarily help with the internal form.  For example, in humans, our external form is bilateral symmetry, but our anatomical insides do not necessarily follow this same symmetry: our hearts are on the left side only, the liver on the right side, and often the right lung has more lobes then the left. Sometimes a human is born with these reversed – inverted along the right/left axis. Scientists have discovered that there are certain types of genes that tend to favor one side of a developing embryo, which correlates fairly highly with the asymmetries noted within our anatomy. So here we’ve noted that although humans have an external symmetry, we do not necessarily have symmetry within our bodies.  This asymmetry is what allows a wide range of animals, who may fall into the same type of symmetry, to have such a wide variety of anatomical insides.  The diversity here is astounding, and something to keep in mind when creating your alien species.

Is it necessary to really understand the anatomy of your alien species?  It can be helpful. For example, in Doctor Who, the Doctor has two hearts. This influences a few of the situations the Doctor finds himself within – and especially when he is regenerating.  This article sums it up nicely: Gallifreyan Physiology.  If both hearts are burnt out, regeneration was impossible; the series itself hints that the two hearts is one of the reasons why the Doctor is stronger and more resilient than humans, and that if one of the hearts is lost, the Doctor becomes significantly weaker.  This is a small difference between the Doctor’s species and humanity, but this difference was utilized off and on through the series.

Although you could get away with using a similar technique like BBC did with the Doctor Who franchise, why cheat and copy humanity?  There’s a lot more possible combinations and forms an alien can be, and with all due respect, it is fairly unlikely that there would be an alien race that looked exactly like us.  Mr. Pickover does a great job explaining why this is so:

In our real universe, there are many reasons why it is unlikely that aliens would take human form. For one thing, the diverse rates and directions of evolution on Earth and the fact that many types of creatures have become extinct show that there is no goal-directed route from single-cell organisms to an intelligent human.  Given only slightly different starting conditions on Earth, humans would not have evolved. In other words, evolution is so sensitive to small changes that if we were to rewind and play back the “tape” of evolution, and raise Earth’s initial overall temperature by just a degree, humankind would not exist.  The enormous diversity of life today represents only a small fraction of what is possible. Moreover, if humans were wiped out today, humans would not arise again.

Thus, finding another planet with species that resemble our own planet, is highly, highly unlikely. So instead of falling into this trap with your alien species, be creative.  Explore some other ideas. It can be easier to just re-use Earth species in your tales, but sometimes it can create new stories and new problems for your characters to solve if you create new species that fits into the environment of your newly created world a bit better. For example, if your world has a much heavier gravity, it is unlikely for very large animals to evolve, so it’s doubtful you’d find any dinosaurs or even large elephants; this is because bones and muscles will be stronger and more compact, and the brain possibly more compact, to stay alive under the higher pressure of gravity. Large animals would have a terrible time trying to breath and regulating parts of their bodies, especially the parts high above the ground, for gravity would be pushing the nutrients downward and away from the taller parts of the body.  It’s much easier for larger (and possibly more delicate) animals to develop on a world with less gravity, for then gravity isn’t such a heavy force upon the structures of the creature.  Also, note that if a creature lives in the sea, it is easier to grow larger, especially larger areas for one’s brain, because the force of the water all around the body provides enough support to help counteract the gravity.  This is why huge whales like the blue whale can develop in our Earth’s oceans, and why you don’t see equivalent land-based animals anymore.  The effects of the environment on your created worlds will heavily influence what types of flora and fauna you will find on that planet, so this is another factor to keep in mind.

It’s interesting to note that in Earth’s creatures, a tube structure for the digestive system seems to be the most favored for evolution. Most Earth organisms above the level of cnidarians and flatworms have a tube structure for a digestive system, and often have two openings such as a mouth and an anus.  The advantages of such a system is that the food can easily move in one direction, and the system can then be divided up into specialized sections to properly breakdown, store, digest, absorb, and store/excrete wastes from the food.  It is quite possible since this seems to be a fairly efficient system, your alien species may have a digestion system similar to it.  Another possibility for a digestion system is a gastrovascular cavity, which is a pouch-like structure with one opening.  An example of this on Earth is flatworms.

When it comes to nervous systems, there are two generalized types: diffuse and centralized.  Mr. Pickover gives a nice definition of both:

A noncentralized nervous system, known as a diffuse nervous system, is found only in lower invertebrates (animals without backbones), particularly among coelenterates like jellyfishes and hydras, which are radially symmetrical. In a diffuse-type system, there is no brain, and the nerve cells are distributed throughout the organism in a net-like pattern.

Even organisms with a diffuse nervous system show some degree of centralization, where there is some part that coordinates information and directs responses.  However, despite this tendency, they often have no brain.  Echinoderms, such as starfish, have a dominant central nerve ring; radial nerves extend outward from this ring, but despite this, it doesn’t have an actual brain.

Brains tend to form in organisms with a centralized nervous system.  These seem to be more common in bilateral symmetrical organisms, which most higher invertebrates and all vertebrates on Earth have.   Once again the environment in which the organism lives plays a key role.  If the organism must be mobile and fairly active, then it tends to develop appendages for manipulating the environment, and its central nervous system develops brains that are fairly close to the primary sense organs, thus reducing the time between sensing the stimuli and responding to it.  If the alien organism tends toward chemically sensing its food, then it’s nose must be near its mouth. This pairing of senses can influence where the sensory orifices may appear in an alien.  If an alien has binocular vision or sound localization, then paired senses will have evolved in order to support those characteristics.  Now, how this brain is housed, may differ greatly from what our own human bodies have evolved.  For example, since it’s the central control system for the alien body, a well protected area to house it may not necessarily be in the head.  It could exist within the alien’s trunk, and still be relatively close to its sensory organs.  The closer it is to the sensory organs, the less a lag time between sensing stimuli and reacting to it.  That time lag could mean life or death for a creature depending on the type of environment in which the creature lives.

Also consider that brains do not necessarily need to evolve higher intelligence to be efficient. Take a look at reptiles. They are highly efficient within their environmental niches, but they are not particularly intelligent as compared to say birds, which tend to be more communicative than reptiles and have more complex social relations.  The types of specialization within the brain can also influence behavior in a species as well.  Birds have a  neocortex, which is an advanced part of the brain that enables humans to plan, learn, and remember.  There is evidence that the emotion of love is made possible through the neocortex.  Reptiles do not have a neocortex, and it may explain why their babies tend to hide to avoid being eaten by their parents; there is no maternal love experienced in those particular species.  When a species evolves more connections between the limbic system – the primitive part that houses delight, disgust, fear, and anger – with the neocortex, more emotional responses develop.  I just used the neocortex as an example of how specialization within the brain may influence the behavior of a species.

I mentioned that brains for mobile and active creatures tend to be nearer to sensory organs; well, the type of sensory organs is also dependent upon the surrounding environment. All creatures need sensory organs, because it allows the organism to respond to the various input signals from their surrounding environment;  often additional senses may be necessary to confirm and refine the organisms perceptions of their environment, which is even more necessary if the organism is fairly intelligent.  Tactile sense is the most basic sense necessary, for it allows the creature to respond to the physical world through touch, helping them to avoid sharp objects, move around objects, and so forth.  Smell is often useful for determining the difference between various chemicals – such as food – in one’s environment, so it’s another possible sense. Our universe is overloaded with sound and light, and so sight and hearing may also be fairly common.  This doesn’t mean the alien species necessarily has to have sight and hearing senses, but that it tends to be more common for most types of environments. There are exceptions to this, for example, creatures that live in caves, where light is scarce, often will have highly developed hearing, tactile, and taste organs and have nearly non-existent sight organs.  Once again, the environment plays a role in the evolution of an organism.   For each of these senses, there is often an external appendages to aid the organism in maximizing detection of the inputs for that particular sensory organ.

In regards to external appendages, the development of specialized appendages for locomotion is often fairly common in various Earth species, so it’s undoubtedly will be for aliens as well. Due to the length of this current discussion, I’ll pause here and in my next installment, I’ll discuss locomotion of aliens and and the possible variety within the locomotion and sensory organs of aliens.  This will finish off Chapter one of Science of Aliens and start us on Chapter two.  Once again, let me know in the comments if you have any questions or insightful thoughts to share on this topic!

Categories: Aliens, Biology, Science, World BuildingTags: , , , , ,


  1. As always very interesting, detailed,
    and well written.



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