What would aliens look like? Of course, it remains an unanswered question, but scientists have a better idea of the possibilities than many people think. This article takes a look at life on Earth and how its environment and biochemistry have shaped it while comparing the huge variety of other factors that could influence the appearance of life on other worlds. It also touches on the subject of technological levels of possible alien civilizations.

One of the most common elements of science fiction and something that humanity has been speculating about for decades is alien life. That alien life exists somewhere out there in the vastness of the Universe is practically a certainty and, while it may forever remain undiscovered, humanity will always ask if it exists and, if it does, what would these strange life forms look like? One thing is almost certain – aliens are not likely to be anything like their popular image portrays them.

The hundreds of humanoid aliens in space operas such as Star Trek or Star Wars, which are ridiculously similar to our own race, will likely forever remain in the realm of fantasy. However, that is not to say that alien life will not be alien in the extreme; in fact, more likely it will be more different than we can possible imagine. While it is all highly speculative at this point, there are three particularly significant factors that we know for sure will have enormous impacts on any form of alien life.

Alternative Biochemistries

Absolutely all life on Earth has a few things in common. It is all carbon-based, relies on water and uses DNA or RNA to define its appearance and biological composition. Almost all life forms also rely on photosynthesis, either directly or indirectly. However, what’s to say that alien life would be so Earth-like? When we consider how diverse life on Earth is, alien life becomes quite unimaginable to many. After all, there is not much similarity between a jellyfish and an elephant, but an alien life form could be so different that it would make them look like siblings!

Alternative biochemistries form a major part in the study of extraterrestrial life and although it is a popular theme in science fiction, the world of science has also given it serious consideration. After all, in order to search for alien life, we need to widen our horizons to be able to consider all of the possibilities.

The most frequently-cited alternative biochemistry considers silicon as an analogue to carbon. These two elements have a lot in common, although silicon also has its drawbacks making it less likely to become a basic element for life. A complex biomass based on silicon would likely consist of organisms living far beneath the surface of an alien planet where the chemical makeup and environment is completely different. Whether an alien life form based on this element would look like a formless mass of gel or an elaborate crystalline structure, however, is entirely conjectural.

Should alien life be carbon-based as it is on Earth, which seems to be more likely, then it is also likely that such life forms will be comparable, in some ways at least, to certain life forms on Earth. However, completely different environmental effects will still have a huge impact on what such life forms would actually look like.

Environmental Effects

Life on Earth thrives in a vast range of environments from hydrothermal vents several miles beneath the surface of the oceans to thermophiles which thrive in places where the temperatures are over the boiling point of water. Life evolves based on its environment but all places where life exists on Earth have some things in common. These characteristics are likely to be quite different on other worlds.

There are so many things which have caused life to evolve on Earth in the way that it has. For example, the presence of the moon creates tides in the oceans and acts as a deflector for potentially deadly impact events from asteroids. A planet with no moon is not likely to have any Earth-like life at all and, if it did, such life would probably only exist in bodies of water or some other type of surface liquid. The tides, after all, have played a major part in the migration of life from the oceans, where it first existed exclusively, to the land.

Gravity is also a major factor. Life forms existing on a planet with a higher or lower gravity than Earth will be very different as a result. On a planet with low gravity, alien life forms would be more likely to be found hovering around in the atmosphere since they would need to spend much less effort on flying. On a planet with a higher gravity, they would need to have a stronger body structure and are more likely to be huge, stout and rather cumbersome-looking creatures.

Photosynthesis is another essential part of almost all life on Earth. This is where light energy from the Sun is converted into chemical energy in order to fuel plant life. Almost all animals and other life forms rely on photosynthesis indirectly as well, since plants are a crucial part of Earth’s biological makeup. It is photosynthesis that is the reason for most plants being green and this, in turn, is due to the colour of the Sun. On a planet orbiting a red dwarf star, much dimmer and redder than our own, any kind of plant life would adapt accordingly. Instead of forests of greenery, a planet orbiting a red dwarf star would more likely be home to forests of black since they would need to absorb light from all wavelengths in order to receive enough.

Technology

If humanity’s own technological achievements, particularly with regards to computer intelligence, are anything to go by, then it is likely that intelligent alien life forms will ultimately transcend their organic forms. Intelligence can become a victim of its own success to such an extent that an intelligent race can actually make free-thinking beings of its own rendering their organic predecessors obsolete. Artificial intelligence of this level is still a long way off and remains in the realm of science fiction, but its existence in the more distant future seems highly likely. An alien race, technologically far ahead of our own, could entirely consist of machines with artificial intelligence. Their organic predecessors would likely be long gone. Artificial intelligence, with its greater tendency towards logic and consistency, would likely outlive any organic race by millions of years as well. Our first contact with an alien species is, thus, quite likely to be with robots than with actual biological beings.

On the other hand, an intelligent alien life form could already be vastly far ahead of humans due to its own inherent biology. There is nothing to suggest that an advanced alien life form couldn’t be so intelligent that they would never even need to rely on things like artificial calculation and decision making. Humanity, after all, relies on computers because it needs to in order to progress in certain areas.

The Kepler Space Telescope, for example, could never have discovered and confirmed the existence of so many hundreds of extrasolar planets if it relied solely on manual labour rather than raw computing power. For people, computers make the impossible possible. Aliens might not even need them. Our first contact with an alien being might be more like meeting a god though to them, we could be little more significant than microbes.