Buzz
If you trust Hollywood’s depiction of alien life, you might envision enormous, gooey beings with a strong disdain for humans. However, since scientists rarely direct films and filmmakers aren't usually experts in science, this portrayal is far from an accurate reflection of the extraterrestrial life that could one day visit Earth.
While it’s likely that such an encounter wouldn’t go smoothly for us, the beings that could alter the course of history for humanity would look quite different from our typical alien imaginings. To clarify, brilliant minds like Stephen Hawking and others in the scientific community have shared their insights into the traits an alien species would need to survive long enough to travel across the galaxy and reach Earth.
10. Hostility
What distinguishes humans from other species in terms of evolution can be summarized by one key factor: aggression. In order for any species to thrive in a given environment, it must face challenges head-on and find ways to overcome them. These challenges are what drive evolutionary changes. For any dominant species on a planet (which aliens would likely need to be), they must have mastered their surroundings.
A study from the University of Missouri proposes that this would mean alien species would exhibit aggressive behaviors—they would colonize and control their environment as part of their growth. If they are more advanced than humans, they may view us in the same way we see livestock and their habitats: as resources to exploit.
9. Pioneers
Any life form capable of reaching Earth must, by definition, be an explorer. When we look to our own history, it’s clear that unexplored lands are often sought for their potential resources. Whether it’s Columbus reaching the Americas, Marco Polo venturing into the East Indies, or the Vikings spreading throughout Europe, humans have always sought out new territories to further their interests.
As Stephen Hawking stated, extraterrestrials are likely to seek out other planets either to colonize or to extract resources. While they might not come to annihilate our world, it's highly probable they will exploit whatever they find to expand their civilization. This behavior is a common trait of advanced species.
8. Resistance to Viruses and Bacteria
A well-known trope in science fiction suggests that aliens, unfamiliar with Earth's bacteria, would succumb to diseases they have no immunity against. Think of the impact smallpox and typhus had on native populations when they first encountered European settlers. But the conquistadors and the Aztecs were both human. Seth Shostak, a senior engineer at SETI, explains that bacteria are only capable of infecting life forms that are biochemically similar to them.
Our bacteria have evolved specifically to thrive in our unique DNA. Even viruses and bacterial infections that affect one species on Earth rarely spread to others. For instance, dogs don’t typically get the flu. Any alien species that reached Earth would most likely be immune to our diseases, so don’t count on a War of the Worlds scenario playing out.
7. They Won’t Feast on Humans
What if their goal is to feed on us? While it’s a chilling thought, it's highly unlikely. Any civilization advanced enough to master space travel would have long since overcome the need to hunt living creatures. The journey from any habitable planet to Earth would take an immense amount of time, and for a species to undertake such a journey, they would need to already have sustainable food sources in place.
Moreover, the digestive systems of a species that evolved in a completely different region of the universe are unlikely to be compatible with the proteins found on Earth. The idea that the minimal food resources here could justify the enormous energy needed to obtain them is far-fetched. By the time they reach us, an alien race would likely be expert in harnessing energy. So, we’re not on their menu.
6. Detached Killers
How many times have people moved into a new home only to discover an unwelcome colony of bugs? How many then proceeded to eliminate every last pest, repeatedly striking with a shoe until the job was finished? No, most people would call an exterminator to fumigate the house and set down poison for any survivors.
Just like any advanced civilization, aliens would likely use technology to their advantage. Before landing on a planet they intend to colonize, they’d probably eliminate the native life forms. Forget about UFOs raining laser beams on government buildings. What we should expect is a swift, probably biological, end to humanity.
5. Not Gigantic Insects
While it’s terrifying to imagine aliens as giant versions of the creepy creatures that scare us on Earth, it's not scientifically feasible. This idea is more about our fear of losing control on our planet, combined with an ingrained aversion to disease-carrying pests.
In reality, the body structure of insects only works on a small scale. They don't have oxygenated blood, so they can't take in enough oxygen from our atmosphere to grow larger. In prehistoric times, when the atmosphere was richer in oxygen, they did grow to alarming sizes, but we’re talking about creatures around a meter long. The image of massive roach-like aliens towering over us is pure fantasy. Sorry, Heinlein.
4. Superintelligence
This is a given. However, in many films, alien species are portrayed as feudal, territorial beings bent on destruction. This doesn’t add up. To achieve interstellar travel, a species must possess a highly advanced intelligence. While they may be aggressive towards other life forms they encounter, and perhaps even their own kind, the idea of them being galactic warlords is highly unlikely.
It's more likely that aliens will be calculated, controlled entities making deliberate decisions—similar to a game of chess rather than dodgeball. Species driven by aggression and limited intelligence tend to focus on conflict and survival. For a civilization to evolve beyond the stages we’ve seen in our own species, they must have learned to put personal differences aside in favor of collective goals. The abilities required for interstellar travel and exploration are aligned with core indicators of intelligence found in nature, such as memory, self-awareness, understanding of motivations, and creativity. These traits must exist before a species can reach significant scientific advancement.
3. No Superhuman Strength
Aliens won't possess superhuman strength. Once they reach the technological expertise necessary for space travel, the need for raw physical power would have long been obsolete. These beings would likely be sleek and well-designed, using minimal energy to fuel their bodies. Energy consumption plays a major role in survival on a large scale. Bigger muscles consume more energy and require more maintenance, pulling resources away from evolutionary development.
An advanced civilization would no longer depend on physical strength to shape their environment. Instead, a species that has invested its evolutionary efforts in social connections, abstract reasoning, communication, and fine motor skills—all essential for developing the capability for space exploration—would most likely have no resources left to dedicate to physical power or speed.
2. Speech and Writing
For a civilization to evolve, communication is essential. In order to coordinate large groups and share vital information, a form of long-distance communication must be established, which plays a key role in societal development. Like humans, aliens would need the capability to communicate intricate ideas and document them, allowing future generations to benefit from accumulated knowledge. Without written communication, it would be nearly impossible for a civilization to transcend the limitations imposed by individual lifespans.
The exact form of communication used by interstellar travelers, and how it may be recorded, remains a mystery. Depending on their surroundings, sound waves might not be the most effective mode of transmission. They might rely on vibrations detected by specialized sensory organs, or perhaps, in line with cinematic portrayals, communicate telepathically. However, as telepathy has not been observed in any other species, it is more likely to be a development brought about by technology rather than a natural ability.
1. Non-Humanoid
This trope appears in numerous TV shows and movies—aliens who look like humans with a bit of face paint (Darth Maul and virtually every Star Trek character come to mind). While this is practical for filmmakers, it is far from plausible in terms of science. Humans evolved due to very specific environmental factors.
Humans evolved by standing upright to cover more ground and free our hands for tool use. Our thumbs came about because of our early arboreal lifestyle. However, on a planet without trees, it’s unlikely that an alien species would develop such an appendage. While we can’t know for certain what an alien species would look like, it is reasonable to expect them to be fast, which would aid in survival and hunting. They would likely have highly developed sensory organs. While it's not guaranteed, we could anticipate features common to most Earth life forms: mouths, eyes, hearing, and efficient movement—likely with legs. Being predators, they may also exhibit traits that reflect this evolutionary history.
+ Functional Appendages
Just as humans have thumbs that allow us to manipulate objects to our advantage, it’s likely that aliens would require similar capabilities. After all, it would be impossible to build or utilize tools without the ability to grasp them. Creatures like giant blobs or those with long, clumsy tentacles are highly improbable.
How could we expect an advanced species to build a spacecraft and navigate it across the vastness of space without the ability to handle and manipulate objects with precision? It's quite reasonable to assume that alien life forms would possess even more sophisticated appendages than our own fingers and thumbs. Just as we adapt our technology to fit our bodies, aliens would likely do the same, possibly making it so that human beings would be unable to operate their devices due to the physiological differences between us.
