Did aliens bring life to Earth? Short answer: There’s no evidence they did. A new study says the first cell would be hard to assemble by chance, but it does not prove that natural origins are “almost impossible,” nor does it show aliens were involved. And that eye‑catching “125 megabytes of information” claim? It’s a model‑based estimate, not a measured fact.
Here’s the story behind the headlines—and what the science actually supports.
Headline “Unreasonable” odds, or unreasonable hype? What a new origin‑of‑life paper really says about aliens, chance, and our earliest dawn
The twist that changes the whole narrative The most dramatic claim in the viral article is that a “proto‑cell” would need about 10^9 bits (roughly 125 MB) of information—so much that chance assembly in Earth’s “primordial soup” would be “almost impossible.” That sounds definitive. It isn’t.
- The source is a July 24, 2025 arXiv preprint by Prof. Robert G. Endres of Imperial College London, titled “The unreasonable likelihood of being: origin of life, terraforming, and AI” (preprint = not yet peer‑reviewed). The paper uses information theory and simulations to argue that assembling a functioning protocell faces formidable hurdles, but it stops short of declaring natural abiogenesis effectively impossible. It explicitly keeps other natural mechanisms on the table and treats directed panspermia as speculative. (Preprint: https://dx.doi.org/10.48550/arxiv.2507.18545; readable PDF view: https://ar5iv.org/pdf/2507.18545)
- That “125 MB” figure is not a lab measurement. It’s an estimate based on “algorithmic complexity”—think “the shortest possible ZIP file that still lets you rebuild a working protocell.” It includes more than just a genome. Meanwhile, real lab baselines for a functioning cell under controlled conditions are far lower: the synthetic minimal cell JCVI‑syn3.0 runs on about 531,000 DNA base pairs—roughly a million raw bits if you count 2 bits per base. That’s orders of magnitude below 10^9 bits. (JCVI‑syn3.0: https://www.jcvi.org/publications/design-and-synthesis-minimal-bacterial-genome)
Translation: Endres’s number is a thought‑experiment upper bound, not a universal minimum. Treat it as a challenging yardstick, not a verdict.
What the paper actually argues—and what it doesn’t
- Verified: It’s a real, recent preprint by a biophysicist at Imperial College. The title really uses the word “unreasonable.” (https://dx.doi.org/10.48550/arxiv.2507.18545)
- Verified: It leverages AI tools (e.g., AlphaFold) and whole‑cell modeling ideas to estimate information content via algorithmic complexity. (https://ar5iv.org/pdf/2507.18545)
- Needs nuance: The paper highlights “formidable entropic and informational barriers,” but it does not compute a definitive probability that rules out natural origins. It explicitly allows for unknown mechanisms or multi‑stage processes that could make life’s emergence more likely. (https://ar5iv.org/pdf/2507.18545)
- Needs nuance: Directed panspermia (life seeded by an advanced civilization) is mentioned as “speculative but logically open.” It’s not presented as the only alternative, and it challenges Occam’s razor. (https://ar5iv.org/pdf/2507.18545)
How the headline grew legs The original article framed the implications as either “life is unimaginably rare” or “someone seeded it”—a neat, dramatic binary. But Endres’s own text is broader, and the wider field includes several plausible stepping‑stones that could boost the odds without needing aliens.
Two key counterweights from current research:
- Bias matters: In digital evolution experiments, if the “soup” doesn’t offer monomers (building blocks) at random but with realistic biases, self‑replicators appear far more often than naïve calculations suggest. In other words, chemistry can stack the deck. (Adami & LaBar: https://arxiv.org/abs/1506.06988)
- Scaffolding helps: Models of RNA‑rich condensates and compartmentalized phases show how early molecules could cluster, replicate, and undergo selection before modern genetics—shrinking the informational hurdles Endres flags. (RNA condensates theory: https://arxiv.org/abs/2412.05396)
The panspermia piece: what’s real, what’s not
- True, as context: Scientists do discuss whether we should seed lifeless worlds in the distant future. One example is Claudius Gros’s “Genesis Project.” This is an academic conversation about ethics and feasibility—not a mission plan. (https://arxiv.org/abs/1608.06087)
- Also true: Meteorites and comets delivered complex organic molecules to early Earth. The Murchison meteorite famously contains amino acids and other organics. But that’s molecular delivery, not proof that complete microbes hitchhiked here. (https://www.pnas.org/doi/full/10.1073/pnas.0403043101)
The early‑Earth clock: short window or fast start? The article is right that Earth had liquid water very early and that candidate traces of early life appear soon after:
- Water/hydrosphere by ~4.3–4.4 billion years ago: Supported by zircon studies. (https://www.nature.com/articles/35051557)
- “Traces of life” at ~4.1 Ga: Carbon‑isotope signals in ancient zircon are intriguing—but debated. Label these “potentially biogenic,” not definitive. (https://www.pnas.org/doi/abs/10.1073/pnas.1517557112)
- Fossils by ~3.48–3.43 Ga: Stromatolite structures from Western Australia are widely accepted. (https://pubs.geoscienceworld.org/gsa/geology/article/51/1/33/618747/Advanced-two-and-three-dimensional-insights-into)
Here’s the twist: A short timeline can be read two ways—either life is so hard that an early start is a fluke, or life is easier under the right conditions, so it starts quickly. That debate is open.
Our reporting trail To cut through the hype, we:
- Read the original preprint and its “unreasonable likelihood” framing. (https://dx.doi.org/10.48550/arxiv.2507.18545; https://ar5iv.org/pdf/2507.18545)
- Checked mainstream coverage that notes it’s a preprint and frames panspermia as speculative. (Phys.org/Universe Today: https://phys.org/news/2025-07-life-emergence-complex-previously-understood.html)
- Traced the 10^9‑bits claim to model assumptions and contrasted it with the JCVI minimal genome benchmark. (https://www.researchgate.net/publication/393983146_The_unreasonable_likelihood_of_being_origin_of_life_terraforming_and_AI/download; https://www.jcvi.org/publications/design-and-synthesis-minimal-bacterial-genome)
- Looked for balancing evidence on biased monomers and prebiotic compartments. (https://arxiv.org/abs/1506.06988; https://arxiv.org/abs/2412.05396)
Key corrections and clarifications
- Bold correction: It’s a preprint, not peer‑reviewed. The results are provisional. (https://dx.doi.org/10.48550/arxiv.2507.18545)
- Bold clarification: The “~10^9 bits (125 MB)” is a model‑dependent estimate of total algorithmic complexity, not a measured minimum. Empirical minimal cells function with far less raw genomic information. (https://www.jcvi.org/publications/design-and-synthesis-minimal-bacterial-genome)
- Bold correction: Not just two options. Beyond “rare” vs. “aliens,” the paper itself leaves room for unknown mechanisms and stepwise processes that could raise the odds of natural origins. (https://ar5iv.org/pdf/2507.18545)
- Bold clarification: 4.1‑billion‑year “first life” signals are debated; call them “possible,” not proven. (https://www.pnas.org/doi/abs/10.1073/pnas.1517557112)
- Bold context: “Seeding life” is an academic discussion, not an agency mission plan. (https://arxiv.org/abs/1608.06087)
- Bold context: Meteorites brought ingredients, not confirmed organisms. (https://www.pnas.org/doi/full/10.1073/pnas.0403043101)
A quick guide: what we know vs. what’s still open What’s solid
- Early Earth had liquid water by ~4.3–4.4 Ga. (https://www.nature.com/articles/35051557)
- Plausible fossils exist by ~3.48–3.43 Ga. (https://pubs.geoscienceworld.org/gsa/geology/article/51/1/33/618747/Advanced-two-and-three-dimensional-insights-into)
- Endres’s study is real, uses information theory, and flags serious hurdles. (https://dx.doi.org/10.48550/arxiv.2507.18545)
What’s plausible but not proven
- Early (4.1 Ga) carbon signals as life: possible, debated. (https://www.pnas.org/doi/abs/10.1073/pnas.1517557112)
- Prebiotic compartments and biased chemistries raising the odds: promising models and lab‑adjacent evidence, still developing. (https://arxiv.org/abs/1506.06988; https://arxiv.org/abs/2412.05396)
What’s speculative
- Directed panspermia (aliens seeding life): logically possible but unproven and, per Endres, a last‑resort explanation that strains Occam’s razor. (https://ar5iv.org/pdf/2507.18545)
- A hard numeric “probability” that rules out natural abiogenesis: no consensus number exists.
Simple analogy to keep it straight Think of “origin of life” like booting a computer without an operating system:
- Endres argues the bootloader plus OS (the protocell) is so structured that you don’t get it by throwing random code at the machine.
- Other researchers show the “hardware” (Earth chemistry) may come with helpful defaults—biased inputs, compartments, cycles—that make simpler boot sequences more likely to start and then grow in complexity.
Bottom line
- No, the new paper does not show that life on Earth was “almost impossible” without aliens.
- Yes, it pushes on a real and uncomfortable question: How do you get enough organized information, fast, from messy prebiotic chemistry?
- The answer may lie in the middle ground—where realistic chemistry, natural selection‑like processes, and stepwise scaffolds change the odds.
What to watch next
- Peer review of Endres’s framework—and whether others agree with its complexity thresholds. (https://dx.doi.org/10.48550/arxiv.2507.18545)
- Experiments that test biased monomer supplies, wet–dry cycles, hydrothermal settings, and RNA condensates as early “bootstraps.” (https://arxiv.org/abs/1506.06988; https://arxiv.org/abs/2412.05396)
- Continued fieldwork refining the earliest life timeline—from ambiguous 4.1 Ga signals to the sturdier 3.48–3.43 Ga fossil record. (https://www.pnas.org/doi/abs/10.1073/pnas.1517557112; https://pubs.geoscienceworld.org/gsa/geology/article/51/1/33/618747/Advanced-two-and-three-dimensional-insights-into)
Trust note We relied on the original preprint, mainstream summaries that flagged its status, and contrasting peer‑reviewed benchmarks and models. We label claims by strength—verified, plausible, or speculative—and show our sources so you can read them yourself.
If life began with help, the help may have come from physics and chemistry, not from the stars. The mystery isn’t over. But the path forward is clearer—and more interesting—than a simple yes‑or‑no about aliens.