Co-written and directed by Steven Spielberg, the upcoming film Disclosure Day takes the existence of extraterrestrial life as a given, exploring the tsunami-level societal shockwave that would follow if the truth were suddenly unveiled. The film is scheduled to open in South Korea on June 10.
Director Na Hong-jin’s Hope fluidly shifts between thriller, action, comedy, and sci-fi. The plot centers on a massive, powerful, and remarkably fast unknown life-form that attacks humans without mercy, eventually forcing the characters to confront the reality of extraterrestrial existence. Hope is slated for a July theatrical release.
Earlier this year, the March release of Project Hail Mary introduced audiences to Grace, a middle school science teacher who awakens in a distant corner of space and encounters Rocky, an intelligent being from another star system. The two advanced life-forms are each handed a critical mission: to save their respective home planets.
As cinematic depictions of advanced extraterrestrial life arrive in rapid succession, they invite a deeper question: Has life actually arisen beyond Earth? More specifically, could alien species undergo the same evolutionary milestones that allowed humans to develop high intelligence and build technological civilizations? Grounded in evolutionary biology and astrophysics, this piece examines those questions from multiple angles—insights that can make watching sci-fi films even more engaging—while exploring a compelling, often overlooked aspect of human nature.
Many "Narrow Gates" in Evolution on the Path to Advanced Intelligence
Charles Darwin, who synthesized evolutionary theory, famously proposed the concept of the "tree of life." Just as physical branches diverge from a single trunk, an ancestral species differentiates into multiple subspecies before settling into entirely distinct species. Examining the emergence of humankind through this lens raises a striking question: from the common lineage shared by humans and other primates, how did we diverge so completely? Why did only humans develop and wield advanced intelligence, and what evolutionary bottlenecks barred other primates from reaching the same threshold?
Each evolutionary bottleneck was exceptionally narrow and unfolded across multiple stages. First, the anatomical structure of the hand changed in tandem with the brain's capacity to control it, allowing early humans to manufacture multi-purpose tools. While chimpanzees possess the intelligence to utilize a branch to fish for insects, no ape has ever been observed intentionally fracturing stone to craft a functional hand ax.
Humans also evolved the unique capacity to run upright; among all primates, we are the only species anatomically built for running. This physiological transition required more than 20 distinct evolutionary modifications, including the development of specialized sweat glands for cooling, a shock-absorbing foot arch, and a highly reinforced Achilles tendon. Equipped for long-distance running, early humans adopted persistence hunting—chasing prey to exhaustion—which provided a highly reliable source of animal protein. This hunting style forced the brain, hands, and developing language skills to adapt together in a powerful feedback loop.
Furthermore, humans mastered the ability to control and create fire. By cooking meat and wild vegetation over flames, they unlocked far higher nutritional value. Chimpanzees never attempted to harness fire. As humans began consuming cooked food, the metabolic energy required by the digestive tract decreased dramatically, allowing the remaining caloric surplus to fuel the evolutionary expansion of the brain. In contrast, when other carnivores achieved nutritional surpluses, the extra energy drove increases in total body mass rather than expanding cerebral capacity.
Following the transition to an upright posture, the human larynx and vocal cords shifted downward. This anatomical descent created a critical acoustic space between the vocal cords and the tongue, enabling the production of a highly diverse range of articulate sounds. Primates remain incapable of speech not just due to lower relative intelligence, but fundamentally because their larynxes never descended to a low position like ours. Speech emerged as a powerful tool for social cooperation, directly boosting the success rates of persistence hunting and allowing individual experiences to be transformed into collective group knowledge. This capacity expanded exponentially once language was preserved in writing, while specialized regions of the human brain developed concurrently to embed language as a core biological instinct.
Through the synergy of hands, persistence hunting, fire, and language, the human brain grew and intelligence advanced. A smarter brain, in turn, made tool manipulation, hunting strategies, the use of fire, and linguistic communication even more precise and powerful.
Even Before Evolution, It Is Hard for a Planet to Meet the Conditions for Life to Emerge
The evolutionary changes required for human intelligence number in the dozens. Given that none of these milestones appeared in other primates, the probability of each individual shift occurring is extraordinarily low. For early humans to emerge, these changes also had to unfold within a highly concentrated timeframe. The probability of all these variables aligning is astronomical—and because they occurred so intensively within a relatively short span for early hominids, that probability can be said to defy imagination.
The odds remain incredibly slim even at the stage before biology begins to evolve. Even if an Earth-like planet exists somewhere in the vastness of the cosmos, the probability of life spontaneously emerging on it is remarkably low. A planet requires a stable atmosphere to sustain life, yet the atmospheric conditions we take for granted simply do not exist on most worlds. For an atmosphere to wrap around and envelop a planet, the body must possess both massive planetary gravity and a robust magnetic field to protect it from solar stripping. Earth-like planets with this exact combination are rare.
Put together, the evidence heavily suggests that there are no other intelligent life-forms in the universe besides humans. In Life 3.0, MIT physics professor Max Tegmark notes that while many people take the existence of advanced extraterrestrial life for granted, he believes the assumption that we are not alone is likely wrong. Tegmark explains that while there may be billions of planets capable of hosting basic life in our galaxy alone, the probability that such life successfully evolves and further develops advanced intelligence remains profoundly uncertain.
He cites expert consensus that intelligent life must pass through multiple severe bottlenecks, a feat requiring unfathomable luck. Tegmark points to the dinosaurs as a prime example: they dominated Earth for more than 100 million years—a span a thousand times longer than the existence of modern humans—yet over that immense timeline, they never transformed into an advanced, intelligent life-form.
Physicists Tegmark and Fermi Question the Likelihood of Alien Life
Long before Tegmark, physicist Enrico Fermi raised similar doubts. If countless extraterrestrial civilizations exist across an ancient universe, he wondered, why have they never appeared to humanity? This led to his famous, straightforward question: "Where is everybody?"
On this topic, Tegmark remains in the minority, as does the author of this piece. The vast majority of people—including many scientists—instinctively imagine that aliens must exist somewhere out there.
However, the main purpose of this article is not merely to dismantle the belief in alien life, though countering it is an intriguing exercise. Rather, the primary focus is to examine the unique human nature revealed by our sci-fi stories, our imagination, and our relentless inquiry into the extraterrestrial.
Remarkably, humanity has poured enormous effort and resources into searching for extraterrestrial civilizations without a single thread of empirical evidence. The most recent major initiative, Breakthrough Listen, was launched in 2015 with backing from tech investor Yuri Milner. This project leverages artificial intelligence to analyze cosmic signals with unprecedented efficiency. Yet among the countless signals processed so far, not a single one has been verified as artificial or extraterrestrial in origin..
Decades-Long Attempts to Detect Artificial Extraterrestrial Signals Yield No Results
The structured effort to locate intelligent extraterrestrial life began in the 1960s under the banner of SETI (Search for Extra-Terrestrial Intelligence). Over the past six decades, more than 60 independent SETI projects have been carried out, but no meaningful signal has ever been detected.
What logic do proponents of alien life put forward to sustain their expectations? In recent books, a science communicator and a mathematician each offered the following justifications:
"If we didn’t exist, aliens wouldn’t exist either; but because we do exist, we cannot abandon our expectations about aliens."
"Given how quiet the universe has been so far, it is clear that aliens either haven’t reached Earth yet, left our planet long ago, or are here right now but have no intention of harming humanity."
The latter statement treats the existence of aliens as an absolute fact. The former conveniently sidesteps the reality that the emergence of advanced life on a distant planet is a probabilistically independent event. Or perhaps it reflects a belief that profound, unproven phenomena like quantum entanglement are somehow at play across the cosmos.
Humans Have an Instinct to Pursue Worlds of Imagination and Story
Projects that consume vast amounts of money and time, alongside the unshakeable belief in aliens, invite us to reflect on a core human trait that is rarely discussed. Alongside emotion, reason, and spirituality, human beings possess an innate drive to imagine, construct stories, and deeply invest themselves in fictional worlds. For now, let us call this our "imaginative nature."
A massive undertaking comparable to our modern search for alien life unfolded during the Stone Age at the Göbekli Tepe site in southern Turkey. Carbon dating indicates this massive stone sanctuary was built around 9500 BCE. Because it was constructed long before the expansion of agriculture or the rise of centralized political authority, we can infer that—unlike the later Egyptian pyramids—it was built entirely through the voluntary will and shared imagination of its creators.
This suggests that humans are born with an inherent love for stories and imagination. If a narrative is captivating enough, we will gladly dedicate our surplus energy and time to pursuing it.
Recently, the U.S. Department of Defense declassified 161 files concerning unidentified anomalous phenomena (UAPs). The Pentagon explicitly noted that these remain "unresolved cases" rather than official confirmations of extraterrestrial life. While these files strengthen the position of skeptics, they are unlikely to shake the convictions of those who believe in aliens. Their underlying premise remains safely insulated: "The absence of evidence showing that aliens exist does not constitute evidence that aliens do not exist."
This powerful imaginative nature does not always serve the strict rules of reason, and can sometimes actively interfere with them. It is astonishing that a species so prone to getting lost in its own fiction has nonetheless engineered such a dazzling material civilization. Even more mysterious is the cosmic process by which early humans defied near-impossible odds to acquire conscious intelligence in the first place. We are the caretakers of that extraordinary history. It is worth pausing, even briefly, to contemplate how we can best honor the wonder and mystery each of us has been given.
