What Would Aliens Actually Look Like?

Speculating about alien appearances has fascinated humanity for decades.

From children sketching imaginative beings to scientists hypothesizing about life beyond Earth, the question remains: What might aliens look like?

Will they resemble us, or will they defy imagination with forms we can barely conceive?

The answer lies in understanding how evolution works at its deepest level, and the results might surprise you.

Why Aliens Might Resemble Us More Than We Think

Hollywood has long depicted humanoid aliens, often due to practical constraints.

In earlier films, special effects required actors to don rubber suits, limiting the scope of alien designs.

Ironically, even with today’s CGI capabilities, filmmakers often create aliens that resemble humans.

Why? Emotional connection. It’s easier for audiences to empathize with creatures that share familiar traits, as seen in James Cameron’s Avatar.

But does this artistic choice align with scientific reasoning? To explore this, we must turn to Earth—the only planet where life has been thoroughly studied.

On Earth, all life traces back to a common ancestor from 3.5 billion years ago, which diversified into an estimated 20 million animal species today.

These species fall into approximately 30 distinct body plans, known as phyla. The Cambrian explosion, over 542 million years ago, marked a time of unprecedented diversification in life forms.

Among them were the five-eyed Opabinia and the flower-like Dinomischus—bizarre creatures that challenge our modern understanding of evolution.

Rerunning the Tape of Life

Stephen Jay Gould, a prominent evolutionary biologist, once posed a thought-provoking question: What if we could rewind the “tape of life” and replay it?

Gould argued that chance plays a monumental role in evolution. A small change in the past could ripple through time, yielding wildly different outcomes.

Take Pikaia, for example—a primitive chordate from the Cambrian era. This tiny creature likely gave rise to all vertebrates, including humans.

But what if Pikaia hadn’t survived? Would some other group have evolved intelligence? Would we now be reading this article with five eyes instead of two?

This raises a compelling point: if Earth’s evolutionary history hinges on such fine details, why should we expect aliens—evolving on entirely different planets—to resemble us?

Evolutionary Convergence

Here’s where the narrative takes a surprising turn.

According to Simon Conway Morris, an evolutionary biologist, evolutionary convergence suggests that aliens might bear more resemblance to us than we’d expect.

Convergence occurs when unrelated species independently evolve similar traits to adapt to comparable challenges.

Dolphins, tuna, and ichthyosaurs all developed streamlined bodies for efficient swimming, despite their vastly different ancestries.

This principle implies that life on other planets might follow similar evolutionary trajectories if faced with analogous environmental pressures.

For example, carbon-based biochemistry is likely universal, as carbon forms stable, versatile bonds.

Water, a solvent crucial for biochemical reactions, is also likely present. Evolution requires a way to store and replicate information, such as DNA or RNA analogues.

These universal constraints might steer alien life toward forms we’d find familiar.

Could Aliens Be Giant Insects?

Let’s address a tantalizing idea: Why not giant, intelligent insects?

Insects dominate Earth’s biodiversity, so it’s reasonable to wonder if they could evolve into advanced life forms elsewhere. However, biology imposes strict limits.

On Earth, insects face challenges due to their external skeletons. Growth requires molting—a process that leaves them vulnerable.

Larger terrestrial animals with exoskeletons would collapse under their own weight during this stage.

Additionally, complex brains likely require a minimum body size and internal skeletons for support.

Instead, intelligence on Earth has often been linked to tool use, problem-solving, and social behaviors.

Apes, dolphins, crows, and even octopuses exhibit such traits, but humans excel due to our bipedal stance, which frees our hands, and our dexterous fingers, enabling tool creation and written language.

Symmetry, Senses, and the Role of Chance

Consider this: humans have two eyes, two ears, and two legs. Is this configuration inevitable for intelligent beings?

Bilateral symmetry—having a left and right side—is a common evolutionary feature among animals.

It aids in movement and coordination, making it likely to appear on other planets with Earth-like conditions.

However, other traits, such as five fingers and toes, are evolutionary quirks rather than necessities.

Early tetrapods experimented with different numbers of digits, but the “five” pattern became fixed. These chance developments highlight the unpredictable elements of evolution.

Searching for Life as We Know It

Currently, our search for intelligent extraterrestrial life focuses on detecting radio or gamma transmissions from star systems with Earth-like planets.

This approach assumes that aliens, like us, rely on technology and inhabit planets with similar conditions.

While it’s easier to search for “life as we know it,” we must remain open to the possibility of life forms that challenge our understanding.

What if alien biology operates on principles entirely foreign to us?

The diversity of life on Earth—ranging from microscopic extremophiles to intricate ecosystems—suggests that the universe’s potential for life is boundless.