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Last year the inner solar system had an interstellar visitor – 3I/Atlas (which stands for the third interstellar object which was discovered by the Atlas telescope). The third ever of anything is by definition a rare event, and so this was scientifically exciting. The comet came into the inner solar system, passing close to Jupiter and Mars, but not to the Earth, went behind the sun, then emerged on its path away from the sun. It is now headed for the orbit of Jupiter and out of the solar system. At first 3I/Atlas displayed a number of minor anomalies. It was behaving sort of like a comet, but with some differences. This fits well, however, with the main hypothesis that it is an interstellar comet – so it’s a comet, but may have a different composition from comets that were formed in our own solar system. This is not almost certainly the case – the comet comes from the thick disc of the galaxy, likely from a low metallicity star system, and has likely been travelling through interstellar space for billions of years, possibly being even older than our own star.

Now that it is passing out of the solar system we can look at all the data that NASA collected and make some fairly confident conclusions. There are a lot of sources of information, but Wikipedia actually has a pretty good summary and list of references. In the end, 3I/Atlas behaved mostly like a typical comet. It formed a tail heading away from the sun, brightened as it got close, then faded away as it moved away from the sun. Spectral analysis found that the comet was unusually rich in carbon dioxide (CO2), with small amounts of water ice, water vapor, carbon monoxide (CO), and carbonyl sulfide (OCS). It also had small amounts of cyanide and nickel gas, which is common in comets from our own solar system. In other words – it is a comet. It did originate from a part of the sky that we had previously calculated would have fewer such interstellar objects, which either makes it especially rare or means that our calculations are off.

Every time we encounter a new interstellar object we gather more data about such objects – how frequent are they, where do they come from, and what is their nature. Right now we have just three data points. After the first one, Oumuamua, we had not idea how common they were because we had just one data point. Now we have enough instruments surveying the sky that we are better able to detect such objects, which are very fleeting. The question was – was Oumuamua a one-off, and we just got lucky to detect something that happens very rarely, or are such objects common. We now have three data points and can conclude that they are fairly common, and we should detect one every few years or so, perhaps even more often if we start looking more.

Interstellar objects are a fairly new astronomical phenomenon, and what typically happens to new astronomical phenomena is that someone asks – could this be an alien artifact? So far the answer has been universally, no. The universe is a very big and complex place with lots of unusual phenomena. Historically speaking we have only just started to examine the cosmos, and are still encountering new phenomena on a regular basis. We have yet, however, to detect anything demonstrably, or even likely, alien. No one would be more excited than me if we discovered a genuine technosignature of an alien civilization. That is precisely why we have to be very careful before leaping to any such conclusions. But sure, ask the question, just don’t leap off the deep end.

What I mean by that is – do not make bad arguments to prop up an alien hypothesis, do not mystery-monger, do not truck in conspiracy theories, and do not draw undue attention to such speculation or present it as anything other than speculation. Every generation seems to have someone, sometimes with a scientific background, who does all of these things. The allure of the alien hypothesis is just too great. It is genuinely fascinating. It is the fast track to fame and attention. You can portray yourself as just being open-minded, brave enough to ask the tough questions, and criticize your colleagues for being closed-minded. Of course, like many things, this is a continuum. A little  is reasonable, more starts to get sketchy, and a lot makes you a crank.

An example of something which I consider to be in the sweet spot of good scientific exploration of the possibility of alien technosignatures is SETI. SETI essentially uses radioastronomy to survey for potential radio signals of alien origin. But they are not just doing this – they are also doing lots of ordinary good radio astronomy. But mixed in with their radio astronomy are methods to screen for signals that might be technosignatures. They are also extremely careful not to make any premature or overblown claims, and they are their own most dedicated skeptics.

At the other end of the spectrum, in my opinion, is Avi Loeb. He has seemed to make a career now out of mystery mongering anything unusual as a possible alien artifact. He claimed that all three interstellar objects might be alien craft. Why is he at the crank end of the spectrum? Because he elevated this possibility prematurely and with a series of really bad arguments, sometimes distorting the data or making bad calculations. He said that Oumuamua might be alien because it was coming close to the Earth, to observe it. He then argued that 3I/Atlas might be alien because it was not coming close to the Earth, to hide from us. He exaggerated its possible size, its apparent lack of a tail, its composition. He made a lot of the fact that the comet’s trajectory is close to the ecliptic, about 5 degrees off, committing a classic lottery fallacy argument. He calculated how likely this specific feature is, but only after knowing it, and did not adjust for all possible features that might be individually unlikely. He engaged in classic post-hoc reasoning. In the end, the predictions of NASA scientists all proved correct – 3I/Atlas is a comet, and displays all the features of a comet. Loeb attracted attention by saying 3I/Atlas might pivot toward the Earth once it emerges from behind the sun. When this prediction failed he did admit it was “most likely natural”, but is still emphasizing its apparent anomalies.

What he is doing is playing coy, which is a common strategy for those who are pushing fringe ideas but who are trying to seem reasonable. All along he said – the most likely explanation is that it is natural. But then follows up with – here are lots of (really bad) reasons why it is unusual and might be alien. This is a win-win for him – in the rare case that he turns out to be right, he is a genius and takes all the credit (keep in mind, if it were alien NASA would have found out all by themselves, with his prodding). If it turns out he is wrong, then he can claim he said all along it was likely to be natural. Either way he sucks up as much oxygen as possible from the media and distracts from the hard-working scientists at NASA doing good work. There is some great and interesting science here. The conclusion that this is almost certainly not an alien craft is a footnote at best, because there was never any good reason to hypothesize that it was.

Loeb is at it again (or still) with a recent post about a “mysterious” Mars cylinder (see the picture above the fold). This is also a common strategy of mystery mongers – comb through tons of data looking for anything unusual, then declare it a mystery. Again – looking for anomalies is a legitimate process of science. Blowing up apparent anomalies into a high-priority mystery is something that an attention-seeking crank would do. In this case others combed through NASA pictures from the Rover and then send it along to Loeb, so he is now a magnet for such things. And again – he admits this is most likely to be just a piece of debris from the Rover itself, or its landing, or whatever. There is now debris on Mars from all the spacecraft we have sent from Earth, so when we encounter a bit of what looks like ordinary debris, that is most likely what it is.

But Loeb is saying that NASA should turn the rover around and travel a few days to go back and take a closer look at this debris. NASA has not responded or commented to Loeb’s statement. This is actually a good operational definition of making too much of an apparent anomaly. Thinking that such anomalies, even when they are likely mundane, should take high priority and redirect our limited resources away from other scientific priorities, is worse than grabbing attention. It is trying to commandeer precious public resources to go on your own wild-goose chases, not because it is good science, but because it serves your own personal agenda.  NASA is perfectly capable of determining the proper priorities for their own rover. They don’t have to go chasing after every piece of space junk because Loeb is trying to grab attention and justify his own dubious professional existence.

The post What Happened to Comet 3I/Atlas first appeared on NeuroLogica Blog.

Physicists are grappling with how the increasing presence of AI will change the nature of their profession

Astronomers have finally cracked a decades-old mystery about red giant stars—how material from their deep interiors makes its way to the surface. Using cutting-edge supercomputer simulations, researchers discovered that stellar rotation plays a powerful role in mixing elements across a previously unexplained barrier inside the star.

Astronomers have finally cracked a decades-old mystery about red giant stars—how material from their deep interiors makes its way to the surface. Using cutting-edge supercomputer simulations, researchers discovered that stellar rotation plays a powerful role in mixing elements across a previously unexplained barrier inside the star.

As the science fiction author publishes the latest novel in his Children of Time series, Children of Strife, he talks to Alison Flood about mantis shrimp, the pleasures of sci-fi and why empathy is so important in his writing

Are we evolving to be more stupid? Humans have a relatively high genetic mutation rate, which has been thought to be driving down our physical and mental fitness – but columnist Michael Le Page finds these mutations aren’t the health risk some make them out to be

Supplying some much-needed skepticism to an episode of the BBC podcast Uncanny.

Learn about your ad choices: dovetail.prx.org/ad-choices

Scientists have turned simple glass into a powerful quantum communication device that could safeguard data against future quantum attacks. The chip combines stability, speed, and versatility—handling both ultra-secure encryption and record-breaking random number generation in one compact system.

Scientists have found a clever way to supercharge ultra-thin semiconductors by reshaping the space beneath them rather than altering the material itself. By placing a single-atom-thick layer of tungsten disulfide over tiny air cavities carved into a crystal, they created miniature “light traps” that dramatically boost brightness and optical effects—up to 20 times stronger emission and 25 times stronger nonlinear signals. These hollow structures, called Mie voids, concentrate light exactly where the material sits, overcoming a major limitation of atomically thin devices.

Scientists have found a clever way to supercharge ultra-thin semiconductors by reshaping the space beneath them rather than altering the material itself. By placing a single-atom-thick layer of tungsten disulfide over tiny air cavities carved into a crystal, they created miniature “light traps” that dramatically boost brightness and optical effects—up to 20 times stronger emission and 25 times stronger nonlinear signals. These hollow structures, called Mie voids, concentrate light exactly where the material sits, overcoming a major limitation of atomically thin devices.

Foams have long baffled scientists because liquid drains from them far sooner than theory predicts. New research shows the reason: the bubbles don’t stay put—they rearrange, opening pathways for liquid to escape. The key factor is the pressure needed to shift bubbles, not just push liquid through them. This insight reshapes how we understand foams and could improve everyday products.

For the first time, scientists have reconstructed the full history of a galaxy outside the Milky Way using chemical clues. By analyzing oxygen across NGC 1365 and comparing it with simulations, they traced its growth over 12 billion years. The findings show how its core formed early while its outer regions were built through repeated mergers. This new approach could transform how astronomers study galaxy evolution.

When we think of asteroids, we almost immediately think of giant rocks bouncing around like the iconic chase scene in Empire Strikes Back, and we often hear how they are remnants from the birth of the solar system. While the asteroids that comprise the Main Asteroid Belt of our solar system are not only spread far apart from each other, they are also not all made of rock. One asteroid approximately the size of the State of Massachusetts called 16 Psyche is made of metal, which planetary scientists hypothesize could be the remnants of a protoplanet’s core that didn’t build into a full-fledged planet. But how did such a unique asteroid form?

What happens in a protoplanetary disk to create planetesimals around a star? We know the general story -- the material begins to clump together and eventually grows from dust grains to rocky bodies capable of sticking together to make planets. But, how does that dust begin the aggregation journey? That's what a research team from the Switzerland wanted to know. So, they did experiments aboard parabolic micro-gravity flights to find an answer.

NSF NOIRLab has completed end-to-end runs of its ecosystem for following up on alerts from NSF–DOE Vera C. Rubin Observatory. The runs demonstrated how multiple NOIRLab-developed software tools, plus a network of telescopes around the globe, will enable quick follow-up observations of the countless transient objects that Rubin will uncover during its ten-year survey.

There’s a kind of storytelling tariff that sci-fi thrillers pay: the alien has to be visually—and physiologically—“other.” The more it resembles us, the less it feels like an invasion, and the less it sells popcorn. So, filmmakers crank the dials. Alien is the perfect example: a creature engineered for maximum dread—extra jaws, parasitic reproduction, and even acid for blood, a brilliant idea because it turns injury into a terrifying weapon. Great cinema. Bad biology.

The alien as a monsterConstraints, Not Monsters

But biology isn’t a special-effects studio. Evolution doesn’t get to pick any chemistry, any anatomy, any habitat, and call it a day. It’s boxed in by constraints: what molecules can build durable, information-rich structures; what solvents allow complex reactions; what temperatures keep chemistry running without shredding it; what gravity and atmosphere allow efficient movement; what energy sources are stable long enough for complexity to accumulate. And here’s the part science fiction usually skips: only a limited range of environments in the universe are likely to be hospitable to the long, fragile process that produces intelligent life at all. If that’s true, then the number of viable “starting conditions” shrinks—and the range of plausible outcomes shrinks with it. In other words, the universe may not be a boundless zoo of monster anatomies. It may be a narrower set of workable habitats repeatedly producing a narrower set of workable body plans—ones that, at a distance, start to look surprisingly familiar.

Carbon is the first and biggest constraint. If you want a system capable of building large, stable molecules that can both store information and do chemistry, carbon is the standout: it forms strong chains and rings, bonds flexibly with common elements (H, O, N, S, P), and supports the kind of combinatorial complexity life seems to require.1 Silicon gets invoked in sci-fi because it sits under carbon on the periodic table, but careful technical reviews conclude that silicon biochemistry faces steep hurdles compared with carbon—especially when you ask for the chemical diversity, solvent compatibility, and long-term stability you’d need for an evolving biosphere rather than a one-off laboratory curiosity.2 Carbon, by contrast, isn’t just “what we have”—it’s what the periodic table offers as good at being life’s scaffolding.

And carbon chemistry, at least as far as we understand it, almost certainly needs a liquid reaction medium. You can think of a solvent as evolution’s workshop: it transports reactants, buffers temperature swings, enables compartmentalization (membranes), and keeps chemistry running long enough for complexity to accumulate. NASA astrobiology treatments make the key point crisply: water is not merely “wet background”; its physical and chemical properties are unusually helpful for life-like chemistry.3 That doesn’t mean life must use water—serious work examines alternatives—but it does mean that when you ask where complex life is most likely to arise, you’re pulled toward a relatively narrow band of worlds with long-lived liquids, stable energy gradients, and conditions that support molecular complexity rather than constantly tearing it down.4

Carbon, by contrast, isn’t just “what we have”—it’s what the periodic table offers as good at being life’s scaffolding.

Once you accept those constraints, the “anything goes” alien starts to look less likely. A restricted set of workable environments tends to funnel evolution toward a restricted set of workable solutions—especially once organisms get big, mobile, and cognitively complex. From there, the argument becomes a cascade: mobility favors efficient body plans; efficient body plans often converge on bilateral symmetry for streamlined, directional movement; and bilateral movers tend to concentrate sensors and processing at the leading end—cephalization—because that’s the part that encounters the world first.5 

Finally, any lineage that’s going to build technology needs not just brains, but some way to manipulate the world with precision—one or more appendages capable of fine control. And Earth at least shows that “high intelligence” is not a one-time miracle: complex brains and sophisticated cognition have evolved multiple times in very different lineages, which is exactly what you’d expect if evolution keeps rediscovering similar solutions to similar problems.6

It Takes a Long Time

For most of Earth’s history, life was microbial. There are abundant signs of life by around 3.5 billion years ago, with plausible evidence reaching back toward approximately 3.8 billion years and earlier, meaning single-celled organisms dominated the planet for the overwhelming majority of its existence.7 Complex multicellular life—and especially animals with nervous systems—arrives strikingly late by comparison: the Ediacaran record pushes recognizable multicellular complexity to roughly approximately 600 million years ago, and the Cambrian explosion (around 540 million years ago) is where diverse animal body plans and their organ systems, including nervous systems, become conspicuous in the fossil record.8 Even “brains,” in any familiar sense, are a comparatively recent evolutionary product of animal history.

And yet, despite billions of years of evolutionary “experimentation” across oceans, lakes, microbial mats, reefs, forests, and ice ages, technological intelligence—the kind that builds radios, telescopes, and spacecraft—emerged only once, and only under a narrow set of ecological circumstances. That doesn’t prove intelligence is unique in the universe, but it strongly suggests that it’s constrained: not every habitable world is equally likely to produce it, and not every habitable environment on a given world is equally likely to nurture it. In other words, the universe may contain places where life is possible, but far fewer where the long chain of transitions to technology can reliably occur.

Evolution is repeatedly solving the same engineering problems under similar constraints.

Long before our ancestors spent most of their time on the ground, their life was shaped in trees—an environment that rewards three-dimensional vision, fine depth perception, color discrimination, and exquisitely controlled hands, arms, and digits for climbing, grasping, and precise manipulation. When some of those primates began living in woodland–savanna mosaics, bipedal walking freed the already dexterous hands for carrying and tool use, effectively repurposing “arboreal skills” into a terrestrial, cumulative technology pathway. That transition—tree-built perception and manipulation deployed on open ground—may be a rare ecological combination, and it helps explain why large brains can evolve in many settings, yet only once has intelligence ratcheted up into an industrial civilization.9

If only a limited set of planetary and ecological conditions can support the long chain from chemistry to cognition, then evolution is repeatedly solving the same engineering problems under similar constraints. And once you narrow the environments where intelligence is even plausible, you also narrow the range of bodies that can thrive there. That doesn’t point to identical aliens—but it does make wildly un-Earthlike “monster designs” (think War of the Worlds with Tom Cruise) less likely, and a recognizable family resemblance—convergent, familiar motifs—more likely.

How the Ratchet Turns

As soon as hominins became more committed to life in woodland–savanna mosaics, a new class of problems moved to center stage: social problems. On open ground, survival often depends less on a single clever trick than on navigating alliances, rivalries, status, reciprocity, and betrayal inside a group—and sometimes between groups. That framing goes back to classic arguments that intellect evolved largely to manage social life.10 It’s also the logic behind the “social brain” tradition: as group life becomes more demanding, selection favors minds better at tracking relationships, intentions, and reputations at scale.11 

In that world, intelligence isn’t just tool-use; it’s the ability to detect cheaters and liars, anticipate others’ moves, and calibrate cooperation—exactly the kind of psychological machinery psychologists Leda Cosmides and John Tooby argued would be favored in repeated social exchange.12 And once you have minds built for social exchange, you have the psychological preconditions for reciprocal altruism—the willingness to help now in expectation of help later—which is one of the foundations of large-scale human cooperation that builds civilizations.13, 14 And when resources are patchy and competition is real, intergroup conflict can further raise the stakes, selecting for coordination, cohesion, and strategic behavior within coalitions. 

Intelligence exists in many lineages; an industrial pathway likely requires intelligence plus a controllable, high-energy lever and a dry-work environment where tools can persist, accumulate, and improve.

Language doesn’t merely label the world; it lets individuals coordinate plans, negotiate alliances, transmit know-how, and build reputations—turning individual cognition into group cognition.15 Most importantly, humans crossed a threshold into cumulative culture: shared intentions, teaching, and high-fidelity social learning allow useful innovations to persist and improve across generations, creating the technological “ratchet” that other smart animals rarely achieve. Humans are distinctive because our know-how doesn’t reset each generation; it accumulates—tools beget better tools in a cultural “ratchet.”16 But brains are expensive tissue, so any species that evolves them must solve an energy-budget problem—through diet quality, provisioning, and other tradeoffs that reliably pay the bill.17, 18

This is where fire and cooking matter: cooking increases the calories you can extract from food and reduces the time and gut investment needed to process it, freeing energy for a larger brain.19 Just as important, controlled fire is a gateway technology—warmth, protection, nighttime sociality, and eventually high-temperature chemistry.20 Intelligence exists in many lineages; an industrial pathway likely requires intelligence plus a controllable, high-energy lever and a dry-work environment where tools can persist, accumulate, and improve.

A skeptic might object that oceans already produce impressive intelligence—dolphins and whales, for example—so why didn’t technology take off there? The point isn’t that marine brains can’t be sophisticated; it’s that an industrial pathway needs more than cognition: it needs persistent tool chains and a controllable high-energy lever.

The decisive step wasn’t just smarter brains—it was solving the problem of memory across generations.

And that points to a subtle filter. Oceans can produce impressive cognition—on Earth in the form of cetaceans and, perhaps, octopus—but water is hostile to the industrial ratchet: fire is hard to control, durable toolkits are harder to store and transport, and metallurgy is effectively off the table.21 On land—especially in variable, resource-patchy habitats—portable tools, teaching, and cooperative planning can compound. That’s why the story is less “savanna created intelligence” than “a particular ecological combination made technology cumulative.”

The decisive step wasn’t just smarter brains—it was solving the problem of memory across generations. Most animals, even very intelligent ones, learn largely within a lifetime. When the individual dies, much of that hard-won knowledge dies with it. Humans broke that bottleneck. We became a species whose best ideas can outlive their inventors, because we can store information—in other minds, in shared practices, and eventually in artifacts and symbols—and then transmit it with unusually high fidelity. That’s the ratchet: innovation that doesn’t evaporate.

This requires more than imitation. It requires teaching, joint attention, and shared goals—what some researchers call “shared intentionality”—so that skills can be transferred efficiently and improvements can accumulate rather than drift. Once a lineage crosses that threshold, technology starts to behave less like a set of clever tricks and more like a compounding system.22 

Language then acts as a compression algorithm for culture. It turns “watch me do this” into “here’s the rule,” making know-how portable, scalable, and teachable to people who never saw the original problem. It also enables coordination at scale—plans, roles, promises, reputations—so groups can build things no individual could.23, 24

And on land, cultural memory can be externalized. Tools can be cached, improved, standardized, and inherited. Eventually information migrates into marks, symbols, and writing—literal memory outside the brain. At that point, progress accelerates, because each generation starts not from scratch, but from a platform built by those before it.

So, What Might ET Look Like?

What does all of this imply about the appearance of extraterrestrial intelligence? Not that aliens will be “human,” as if evolution everywhere is destined to reproduce our exact anatomy. Evolution is too contingent for that. But it’s not completely random. If intelligence that builds technology is constrained by chemistry, physics, and ecology – and if similar constraints repeatedly force similar solutions—then truly alien intelligence may come with a surprisingly familiar set of design motifs.

Humans broke that bottleneck. We became a species whose best ideas can outlive their inventors, because we can store information … and then transmit it with unusually high fidelity.

Start with the big one: directional movement in a complex world. Once organisms become large, mobile, and behaviorally flexible, the “engineering problem” of getting around efficiently tends to favor bilateral symmetry—a front and a back, a left and a right—because it streamlines movement and organizes the body around a direction of travel.25 Bilateral movers also tend toward cephalization: concentrating senses and information processing at the leading end, because that’s the part that meets the environment first.26 In plain terms, if something is navigating the world and making decisions quickly, it’s likely to be built around a “front end” where sensing and control are concentrated (and, less glamorously, but no less practically, a “waste end” where, well, waste products are dispensed).

Then comes the key requirement for technology: manipulation. A brain can model the world all day, but technology requires a high-bandwidth interface between mind and matter: appendages capable of precise, repeatable control. On Earth, that role is played by hands and digits—originally honed for climbing and grasping in trees—later repurposed for shaping objects, carrying toolkits, and building cumulative tool traditions. This doesn’t mandate five fingers, or even “arms” in the human sense. But it strongly suggests that technological intelligence will be paired with one or more manipulators—structures evolved for fine control, not just locomotion.

Finally, technological intelligence requires culture that compounds. If each generation must rediscover the basics from scratch, there is no sustained trajectory toward industry. The transition to cumulative culture—high-fidelity social learning, teaching, shared intentions, and the ability to preserve and improve innovations—creates the technological ratchet.27, 28, 29 Once a lineage crosses that threshold, intelligence becomes more than cleverness; it becomes a system that accumulates, and that accumulation eventually externalizes into tools, structures, symbols, and records. In other words: even if the bodies vary, a technological species will likely have something analogous to language, teaching, and external memory—because without those, the ratchet stalls.30, 31

Put those pieces together and a rough “family resemblance” emerges: not humans exactly, of course (there’s contingency again), but mobile, bilateral organisms with front-loaded sensing/processing, manipulators, and a cultural transmission system that lets knowledge outlive individuals. That is the opposite of the cinematic monster. It’s less a nightmare creature and more a familiar engineering solution—built under unfamiliar skies.

Caveats and Conclusions

A skeptic’s first objection is an obvious one, namely that Earth is a sample size of one. Any story about extraterrestrial biology risks generalizing from the particular to the universal. That caution is warranted. Our lineage’s specific path—arboreal heritage, bipedalism, the woodland–savanna mosaic—may be historically contingent. Different worlds could produce intelligence by different routes (although it is not clear how), and even on Earth, high cognition appears in multiple lineages.32 So, the claim here should be modest: not “ET must look like us,” but “constraints bias evolution toward a limited menu of workable solutions.”

The Grey is a popular alien figure because it’s a humanoid distilled to a few cues: bilateral symmetry, a head-dominated body plan, and exaggerated eyes. Those broad motifs actually align with what a constraint-based view would predict. But the specific “Grey” is also a cultural icon with a traceable modern history—especially after Whitley Strieber’s Communion (1987) and its widely reproduced cover image. So, it’s better understood as a modern cultural meme than as a biologically derived prediction.

The “Grey” alien.

A second objection is this: what if technology doesn’t require fire and metallurgy? Perhaps some species develop a different high-energy lever or a different materials pathway. That’s possible. But the broader point still holds: industrial-scale technology requires some means of harnessing scalable energy and building durable tool chains. Whatever substitutes exist, they still must operate under the same physical logic: persistent artifacts, repeatable processes, and the ability to store and transmit complex know-how over long spans of time. 

For example, we know Earth’s atmosphere didn’t always permit fire because oxygen arrived late—and we can see that transition written in the rocks. For much of the Archean, oceans carried abundant dissolved ferrous iron (Fe²⁺); when oxygen produced by early photosynthesizers (e.g., blue-green algae that scientists call cyanobacteria) began reaching surface waters, it oxidized Fe²⁺ to insoluble ferric iron (Fe³⁺) that precipitated in vast banded iron formations (BIFs), essentially recording oxygen’s first sustained appearance as it was “soaked up” by iron sinks. Around 2.4 to 2.3 billion years ago—during the Great Oxidation Event—atmospheric O2 rose from trace levels to much more significant amounts, while BIF deposition eventually waned as the ocean’s iron sink diminished and broader oxygenation progressed. 

That history matters for our argument because recognizable, combustion-driven technology depends not just on brains, but on a planet reaching an oxygen state that reliably supports open-air fire and high-temperature chemistry—the “oxygen bottleneck” for technospheres. That is why the “oxygen bottleneck” argument is useful: it highlights that recognizable, combustion-driven technospheres are not guaranteed by intelligence alone—they depend on planetary conditions that enable certain kinds of energy use.33

So, the claim is not inevitability, but probability. Constrain the environments, and you constrain the solutions. And that means the wildest designs of monster cinema are not the most realistic expectation. They are the least constrained.

Science fiction thrives on the alien as shock: the creature that breaks every rule and looks like nothing that ever walked, swam, or crawled on Earth. Alien is a masterpiece precisely because it is so unconstrained—a physiology engineered for dread. Great theater. But real evolution does not have that freedom. Biology is boxed in by chemistry, by solvents, by energy budgets, by gravity and materials, by the logic of movement and sensing, and by the requirements of cultural accumulation.

The details will be alien. The motifs may not be.

That’s why the best prediction for extraterrestrial intelligence is not a monster, but a constrained organism that has solved a familiar set of problems in a workable way: a body built for efficient movement, sensors and processing concentrated forward, appendages capable of precise manipulation, and a culture that can store and transmit information across generations so that technology compounds. The details will be alien. The motifs may not be.

If we ever detect a true technosignature—or one day meet its makers—the surprise may not be how strange they are. The surprise may be how recognizable the underlying design logic feels.

To understand the Universe we see around us today, we have to understand its past. Some hard-to-find ancient stars, called Population II stars, preserve evidence from the ancient Universe. Astronomers finally found one.

The Neanderthal population shrank during a cold spell around 75,000 years ago, and the loss of genetic diversity may have contributed to their eventual extinction

Since 2016, Antarctic sea ice extent has been declining sharply – now scientists are piecing together how strong winds and warm deep water have played a part in this abrupt transition

Reader Thomas from Marginal REVOLUTION sent me the linked article piece, which shows a video of the 1957 doo-wop hit “Little Darlin'” by the Diamonds. If you’re my age, you’ll remember it.  I always thought it was a serious song, and apparently so did most Americans, but the first comment says this:

From what I recall, the Diamonds were a conventional vocal group who recorded “Little Darlin'” at the end of a session as a kind of joke song – a parody of the Ink Spots and Mills Brothers. Fortunately for them, the studio musicians joined in with perfectly irresistible beat and the song became a rock and roll hit. Early rock and roll was born as parody as much as anything else, like Elvis’s Jokey rendition of Bill Monroe’s “Blue Moon of Kentucky” turning out to be the founding document of rockabilly.

Really? And then they present the video, which, unlike any music video I know from that era, shows the group clowning around. Have a look at the video for a hit song (more cowbell!). But yes, this is the original song. which went to #2 on the Billboard charts.

To get to the bottom of this, I sent to AI, in particular Grok. Sure enough, the bot pronounced it a parody after scanning what’s published about it.

“Was “Little Darlin'” by the Diamonds a parody song?”

Yes, “Little Darlin'” by The Diamonds (1957) is widely regarded as a stylistic parody/satire of the doo-wop genre—not a lyrical parody like a Weird Al track (the words and melody are the same), but a deliberately exaggerated, campy cover that poked fun at the over-the-top clichés of the style.Here’s the story, straight from music historians:

• The song was written by 16-year-old Maurice Williams and first recorded in January 1957 by his group The Gladiolas (on the Excello label). Their version was a straight, heartfelt R&B/doo-wop track with a Latin-tinged rhythm, falsetto, spoken bridge, and percussion. It charted modestly (#11 R&B, minor pop crossover).
• The Diamonds (a Canadian quartet) rushed out their cover just a month later on Mercury Records. It was reportedly a last-minute, end-of-session lark—they had about 15 minutes left, no drummer, so they improvised with castanets. Lead singer Dave Somerville and the group leaned hard into the nonsense syllables (“ai-ya-yi-yai-yai-ya,” “wella-wella,” etc.), hamming it up with theatrical flair. They even performed it in an over-the-top way on TV (like The Steve Allen Show).

AllMusic critic Stephen Thomas Erlewine noted that the vocal phrases “verge on self-parody… which may be why The Diamonds’ version is superior.” Radio historian John Gilliland (on the Pop Chronicles series) explicitly stated that their recording “was in fact a parody of the genre.” Other sources describe it as a “joke song,” “satire of doo-wop,” or “intended as a satire” with “campy vocal delivery.”Despite (or because of) the tongue-in-cheek approach, it became a monster hit: #2 on the Billboard Hot 100 for eight weeks (behind only Elvis’s “All Shook Up”), the biggest version by far, and now the definitive classic. The original Gladiolas take is respected by R&B fans but far less known.It’s a classic example of a white cover version (common in the 1950s) that amplified the style for mainstream appeal—here with humor that stuck. Later, Elvis Presley covered the Diamonds’ arrangement on his final album Moody Blue, and Joan Baez even recorded an actual lyrical parody.

From Wikipedia, we learn that the hit version was actually a re-recording of a song recorded just a month earlier by a black group, the Gladiolas, one of whose members wrote the song. There’s also a brief not about the parody aspect:

It was written by a 16-year-old Maurice Williams with both melody and doo-wop accompaniment strongly emphasizing a calypso rhythm. First recorded in January 1957 by Williams’ group the Gladiolas, it was quickly released as a single on Excello Records, a small swamp blues label owned by Nashville record man Earnie Young, who was responsible for creating the song’s Latin feel, naming the group and ensuring Williams would retain the song’s publishing.

The recording, inspired by a book Williams was writing, and originally called “Little Darlin’/ The Beginning,” is noted for its trademark doo-wop falsetto by Fred Mangum and its spoken bridge by Williams (“My Darlin’ I need you …”). The Gladiolas were from Lancaster, South Carolina, where they had been together since high school.

The Diamonds‘ successful cover version followed a month later. The Diamonds were a Canadian pop group that evolved into a doo-wop group. The Diamonds’ version reached number two in sales for eight weeks on the Billboard Hot 100. Billboard ranked this version as the No. 3 song for 1957. In Canada, the song was No. 11 on the premiere CHUM Chart, May 27, 1957.

The Diamonds’ version is generally considered superior. AllMusic critic Stephen Thomas Erlewine argues that the Diamonds “Little Darlin'” is an unusual example of a cover being better than the original:

[T]he Diamonds’ take remained the bigger hit, and over the years, the better-known version. Normally, this would have been an outrage, but there’s a reason why the Diamonds’ version has sustained its popularity over the years: it’s a better, fiercer recording. Both versions are good, even if they’re a little silly, because it’s a good doo wop song, giving each member of the quartet a lot to do. At times, the vocal phrases verge on self-parody — the “ai-ya-yi-yai-yai-ya”‘s or the “wella-wella”‘s — which may be why The Diamonds’ version is superior.

On the Pop Chronicles, host John Gilliland claimed that their version was in fact a parody of the genre. Nonetheless, “Little Darlin'” (primarily the Diamonds’ version, but to some extent the Gladiolas’ version) remains an all-time rock ‘n roll R&B classic.

Here’s the original version by The Gladiolas, and sure enough, it’s pretty much like the parody (or cover), including the talking interlude. It was not a hit. Is this cultural appropriation?