Scientists Have Put A Wild Number On How Hard It Was For Life To Begin

Life had to start somewhere. Before the first cell could reproduce, before DNA could carry instructions and before anything resembling a living organism existed, chemistry had to somehow assemble enough useful information to get the process moving. Scientists still do not know exactly how that happened, and a new calculation has put some extraordinary numbers around just how difficult the problem may have been.

Robert Endres, a biophysicist at Imperial College London, approached the mystery as an information problem. Instead of asking only what chemicals were available on early Earth, he asked how quickly useful biological information could have accumulated before the molecules carrying it broke apart. His answer depends heavily on one uncertain property: how long early chemical processes could keep moving in a productive direction before effectively losing their progress.

The First Cell Needed An Enormous Amount Of Information

Endres starts with one of the simplest self-replicating organisms known, Mycoplasma genitalium, whose genome contains roughly 500 genes with around 1,000 base pairs each. At two bits of information per base pair, that puts the genome alone at roughly one million bits. A functioning cell needs much more than a sequence of DNA, however. Proteins have to fold correctly, cellular structures have to operate and countless chemical interactions have to happen in the right order. A computational model of the organism can be compressed to around 140 megabytes, equivalent to roughly one billion bits of information.

That creates a brutal deadline when placed against the history of early Earth. Endres gives prebiotic chemistry roughly 500 million years in which to move from nonliving chemistry toward something resembling a protocell. Spread one billion bits across that period and the required information accumulation rate works out to around two bits per year. That sounds almost laughably slow, and under certain assumptions it is slow enough for abiotic emergence to remain feasible. The catch is that useful chemical information does not necessarily accumulate in a neat line.

Early Earth May Have Had A Melting Chemical Library

Imagine having access to millions of potentially useful chemical combinations, but every one of them starts disappearing almost as soon as you find it. Endres estimates that the prebiotic environment may have contained between one million and ten million bits of potentially useful chemical information, while complex organic molecules could survive for roughly a day before hydrolysis, ultraviolet radiation or oxidation destroyed them. The problem then becomes less like building something from an unlimited supply of parts and more like trying to assemble an instruction manual while the pages are constantly burning.

His comparison is striking. Picture a library containing ten million books, with every book destroying itself 24 hours after being removed from the shelf. Your job is to create a manual explaining how to build the first living system before the information disappears. Under that scenario, chemistry would have to inspect roughly 100 books every second simply to keep up with the losses. The calculation does not prove that life could not emerge naturally. Instead, it exposes the enormous uncertainty surrounding the process and identifies a specific question scientists can investigate: how strongly could early chemistry preserve useful progress?

One Tiny Change Sends The Numbers Into Space

That question becomes especially important when the chemistry is treated as a random walk rather than a straight path toward life. A random process can make progress and then lose it, meaning that the crucial property is persistence. If chemical reactions can maintain a productive direction for long periods, the path toward complexity becomes easier. If that persistence disappears quickly, the system repeatedly gives up the progress it has already made.

Endres calculates that reaching protocell-level complexity within 500 million years under a minimum-speed random-walk model would require a persistence time of around 250 million years. That is half the entire available window. Reduce the persistence to one year and the expected waiting time stretches to around ten million times the current age of the universe. Reduce it to a single second and the number becomes even more extreme, reaching what Endres describes as roughly 100 trillion universes stacked end to end.

The headline-grabbing conclusion follows from that calculation. Endres writes that “without immense persistence, life’s emergence becomes cosmologically implausible.” But he immediately warns that the model may be too restrictive. The calculation is therefore less a declaration that aliens must have created life and more an attempt to quantify a problem scientists have struggled to put numbers on.

The Alien Seeding Idea Is Much Older Than This Calculation

That is where one of the strangest ideas in the history of origin-of-life research comes back into view. In 1973, Francis Crick and Leslie Orgel proposed a concept known as directed panspermia, suggesting that an advanced extraterrestrial civilisation could theoretically have sent microorganisms toward another planet. The idea was speculative from the beginning, and the scientists presented it as a possibility rather than established evidence that humans were deliberately planted on Earth.

Crick and Orgel pointed to questions surrounding the universality of the genetic code and the role of certain elements in biology. But the evidence was nowhere near strong enough to demonstrate an extraterrestrial origin for life. Endres is equally cautious. His paper notes that directed panspermia effectively moves the difficult origin-of-life problem somewhere else, because an extraterrestrial civilisation would itself need to have developed biology capable of creating or transporting the organisms.

That leaves a major problem unresolved. If life was delivered here, where did the first life in the universe come from? Alien seeding can potentially explain how life travelled between worlds, but it does not automatically explain how life first appeared.

Asteroid Bennu Shows Space Has The Ingredients

One reason the idea continues to attract attention is that scientists now have access to material that spent billions of years away from Earth. NASA’s OSIRIS-REx mission returned samples from asteroid Bennu in 2023, giving researchers pristine material from an ancient object that formed during the early history of the solar system. Analyses found 14 of the 20 amino acids used by life on Earth to build proteins, along with all five nucleobases used in DNA and RNA and abundant ammonia. Those discoveries show that important chemical ingredients associated with life can exist beyond Earth, although they do not show that life itself exists on Bennu or that those ingredients arrived here as living organisms.

Jason Dworkin, the mission’s project scientist at NASA’s Goddard Space Flight Center, compared Bennu to a pantry containing ingredients without the conditions needed to turn them into a finished meal. That distinction is crucial. Finding amino acids and genetic building blocks in an asteroid is evidence that prebiotic chemistry can happen in space, but it is not evidence that an asteroid carried the first cells to Earth. It does, however, strengthen the case that some of the raw materials required for life were widespread throughout the early solar system. NASA has also reported additional organic compounds in Bennu samples, reinforcing the picture of an ancient environment rich in chemistry relevant to the origins of life.

A Nearby Planetary System Could Make Panspermia Easier

If life can travel between worlds, distance becomes one of the biggest obstacles. Our own solar system contains enormous gaps between planets, making natural transfer of biological material a difficult process. But some planetary systems are far more compact. TRAPPIST-1, around 40 light years from Earth, contains seven roughly Earth-sized planets packed relatively close to their host star.

Planetary scientist Fred Ciesla has modelled how material could move between worlds in such a system. His calculations suggest that roughly 10% of material blasted from one planet could reach another planet in the habitable zone within a century. “It’s a very compact system. So the efficiency of something being launched from one to the other is much greater,” Ciesla said. He has also argued that there is “merit to the idea of life making its way from one planetary system to another.”

That does not establish that life actually travelled between those planets. It simply shows that the physics of material transfer can look very different in tightly packed planetary systems. If microorganisms could survive the journey, systems like TRAPPIST-1 offer a very different environment for panspermia than our comparatively spread-out solar system.

The Alien Theory Still Has A Major Problem

Endres’ work does not conclude that extraterrestrials seeded Earth. In fact, his own conclusion points in the opposite direction. The paper is a preprint rather than a definitive final answer, and many of its central quantities are estimates built from other estimates. Endres explicitly says the goal is “not to deliver a definitive conclusion but to structure a quantitative discussion.” That distinction matters because the enormous numbers produced by the model depend on assumptions about how prebiotic chemistry behaved.

His conclusion is also more conservative than the headline surrounding the alien hypothesis might suggest. Endres writes that “Occam’s razor weighs in” and argues that abiotic evolution remains a viable explanation, even if the process turns out to be extremely slow and difficult to understand. He also argues that invoking extraterrestrial terraforming adds another layer of explanation without providing a constraint that forces scientists to accept it.

Physicist Paul Davies has reached a similar position after decades of studying the origin-of-life problem. He has described older panspermia arguments as containing “a germ of truth” while remaining sceptical about the idea that an advanced civilisation deliberately seeded Earth. The distinction is simple: life arriving from somewhere else is physically conceivable, but there is currently no evidence establishing that this is what happened here.

The Real Mystery Is Still Sitting On Earth

The most interesting part of the calculation may therefore have nothing to do with aliens. It is the fact that scientists can now identify the specific missing piece they need to understand better. Early Earth clearly contained water, minerals and organic chemistry, while material from asteroids shows that many life-related ingredients were available beyond our planet as well. What remains unclear is how those ingredients became a self-sustaining system capable of storing information, reproducing and eventually evolving.

The key possibilities researchers are wrestling with include:

• Chemical persistence: Early reactions may have found ways to preserve useful progress instead of repeatedly starting over.
• Environmental cycles: Wetting, drying, heating, cooling and mineral interactions could have concentrated chemicals and pushed reactions in particular directions.
• Extraterrestrial delivery: Asteroids and other bodies may have supplied important ingredients, even if they did not deliver living organisms.
• Unknown chemistry: The earliest stages of life may have followed pathways that modern models do not yet capture.

That leaves the alien-seeding hypothesis where it has always been: possible in principle, fascinating to consider and unsupported as an explanation for Earth’s first life. The evidence from Bennu makes the universe look chemically fertile, but chemistry is still not biology. NASA’s Bennu studies themselves stress that the samples contain ingredients associated with life rather than evidence of life itself.

And there is still plenty left to investigate. The Bennu sample returned more than 120 grams of asteroid material, and researchers continue to distribute portions to laboratories for detailed analysis. Every new measurement can reveal another piece of the chemistry that existed before life appeared. The mystery is no longer simply whether the ingredients existed. Scientists are now trying to work out what could have made those ingredients keep going long enough to become something alive.

For now, there is no scientific evidence showing that humans were seeded by aliens. There is, however, a much stranger fact hiding underneath the speculation: nobody has yet demonstrated exactly how nonliving chemistry crossed the enormous gap into the first living system. That unanswered step remains one of science’s biggest puzzles.

Sources:

• Endres, R. G. (2025, July 24). The unreasonable likelihood of being: origin of life, terraforming, and AI. arXiv.org. https://arxiv.org/abs/2507.18545
• Orlic, C. (2024, February 20). The origins of directed panspermia. Scientific American. https://www.scientificamerican.com/blog/guest-blog/the-origins-of-directed-panspermia/