The Key to Interstellar Travel Might Already Exist—But a Quirk of Evolution Is Holding Us Back, Scientist Claims

Here’s what you’ll learn when you read this story:Our brain’s evolution makes it nearly impossible to commit to a multi-generational mission like interstellar travel, says one evolutionary anthropologist.However, humans have worked successfully on other long-term projects. And a blueprint for extreme long term cooperation exists in other Earth species. An interstellar mission may be ultimately possible, but it would need careful long-term planning as well as rules and rituals to keep the enterprise going long enough to find another world to call home.Why travel to a star? Existential threats such as asteroid impacts, climate change, and an unforeseen AI catastrophe, long the stuff of science-fiction, seem ever more immediate. In the long run, planetary fragility and stellar mortality—the eventual death of our sun—might prompt us to turn our gaze starward. Stars might someday offer us access to energy and resources beyond Earth’s reserves, or the promise of human expansion and legacy, allowing us to colonize intergalactic worlds. However, the nearest star system to Earth is Alpha Centauri, a constellation about 4.37 light-years away. Using existing propulsion technology, it would still take tens of thousands of years to reach Alpha Centauri; even a breakthrough starshot propellant, such as ground-based laser arrays or fusion-powered craft, would span several lifetimes. Such distances stretch beyond human reckoning—to cross them, we’d need to survive not just the physics of space, but human biology.Evolutionary anthropologist Kathleen Bryson, PhD, believes our biggest obstacle to interstellar travel isn’t propulsion or fuel, but the human brain. We’re a species built for immediacy: securing the next meal, protecting our kin, scanning the horizon for threats. That wiring, Bryson argues, has served us well for a few hundred thousand years on Earth, but confers a near impossibility to commit to the multi-generational persistence interstellar travel would demand. Yet, evidence of cooperation on cosmic timescales can be found in nature: the hive mind of bees, the migration patterns of salmon, the far-flung networks of fungi. If evolutionary blueprints for long-term collaboration exist, might they be harnessed for century-scale projects where payoffs are far away and spread across people not yet born?“Getting to the stars isn’t just building a ship; we would need to keep a species healthy and cooperative across generations, with bodies and social cultures that don’t fall apart on the way,” says Bryson, currently a visiting researcher at Oxford University who studies how our evolutionary instincts shape behavior. Technology might enable us to solve the problem of materials, she argues, but human instincts favoring the short-term present an especially formidable challenge. “We’re good at looking after ourselves and our allies in our lifetimes—a star mission asks us to keep cooperating and caring for people we’ll never meet, for centuries.”Assuming we could engineer a ship required for interstellar travel, suspended animation and procreation would present other challenges. Even if the ship’s initial crew slept for only part of the journey, Bryson points out, there would be practical concerns: how to sterilize an environment to ensure that the human microbiome (full of living bacteria) would also “hibernate”? How to maintain genetic diversity among the crew’s limited gene pool? How to put a stop to generational rebellion, a likely outcome when mission pilots’ great-great-great-grandchildren awaken to an undertaking they’d never agreed to? “Cathedrals prove we can cooperate for a few centuries, but an interstellar mission needs unbroken cooperation through leadership changes, cultural drift and resource shocks,” says Bryson. “One badly behaved cohort could unravel the whole thing.”Still, we’ve managed vast, coordinated efforts before—the international space program, the eradication of smallpox, the Human Genome Project. These endeavors might count as evidence that we can sustain long-term cooperation. What would a society capable of interstellar travel need to look like, psychologically or socially? Bryson believes that institutions, careful planning, and constant upkeep might be the keys to preventing mission drift. Clear rules, transparent monitoring, and rituals that keep the enterprise vivid for people who will never see the destination could stretch our horizon on a generation ship.Bryson also looks to nature, where other species have evolved cooperative capacities over millennia in response to their environments. For instance, ants and bees show extreme division of labor, but these are mostly kin-based systems. By contrast, elephants, corvids, dolphins, certain non-human primates such as chimpanzees, and wolves often show long-term give-and-take with non-kin, which is a kind of delayed reciprocity. “Humans are likewise extraordinarily cooperative, and we practice delayed reciprocity, too,” says Bryson. Such a massive undertaking would certainly demand extreme delayed reciprocity, but it’s not inconceivable.So, would Bryson climb aboard a ship making a cosmic pilgrimage? “I’d probably turn it down, because I’m a nervous flier.” Indeed, the siren call to terraform the stars can’t quite compete with our home on Earth, imperfect as it is.