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To err is human, which is really not a very good excuse.

And to err as a scientist is worse, of course, because depending on science is supposed to be the best way for people to make sure they’re right. But since scientists are human (most of them, anyway), even science is never free from error. In fact, mistakes are fairly common in science, and most scientists tell you they wouldn’t have it any other way. That’s because making mistakes is often the best path to progress. An erroneous experiment may inspire further experiments that not only correct the original error, but also identify new previously unsuspected truths.

Still, sometimes science’s errors can be rather embarrassing. Recently much hype accompanied a scientific report about the possibility of life on Venus. But instant replay review has now raised some serious concerns about that report’s conclusion. Evidence for the gas phosphine, a chemical that supposedly could be created only by life (either microbes or well-trained human chemists), has started to look a little shaky. (See the story by well-trained Science News reporter Lisa Grossman.)

While the final verdict on phosphine remains to be rendered, it’s a good time to recall some of science’s other famous errors. We’re not talking about fraud here, or just bad ideas that were worth floating but flopped instead, or initial false positives due to statistical randomness. Rather, let’s just list the Top 10 erroneous scientific conclusions that got a lot of attention before ultimately getting refuted. (With one exception, there will be no names, for the purpose here is not to shame.)

10.  A weird form of life

A report in 2010 claimed that a weird form of life incorporates arsenic in place of phosphorus in biological molecules. This one sounded rather suspicious, but the evidence, at first glance, looked pretty good. Not so good at second glance, though. And arsenic-based life never made it into the textbooks.

9. A weird form of water

In the 1960s, Soviet scientists contended that they had produced a new form of water. Ordinary water flushed through narrow tubes became denser and thicker, boiled at higher than normal temperatures and froze at much lower temperatures than usual. It seemed that the water molecules must have been coagulating in some way to produce “polywater.” By the end of the 1960s chemists around the world had begun vigorously pursuing polywater experiments. Soon those experiments showed that polywater’s properties came about from the presence of impurities in ordinary water.

8. Neutrinos, faster than light

Neutrinos are weird little flyweight subatomic particles that zip through space faster than Usain Bolt on PEDs. But not as fast as scientists claimed in 2011, when they timed how long it took neutrinos to fly from the CERN atom smasher near Geneva to a detector in Italy. Initial reports found that the neutrinos arrived 60 nanoseconds sooner than a beam of light would. Faster-than-light neutrinos grabbed some headlines, evoked disbelief from most physicists and induced Einstein to turn over in his grave. But sanity was restored in 2012, when the research team realized that a loose electrical cable knocked the experiment’s clocks out of sync, explaining the error.

7. Gravitational waves from the early universe

All space is pervaded by microwave radiation, the leftover glow from the Big Bang that kicked the universe into action 13.8 billion years ago. A popular theory explaining details of the early universe —  called inflation — predicts the presence of blips in the microwave radiation caused by primordial gravitational waves from the earliest epochs of the universe.

In 2014, scientists reported finding precisely the signal expected, simultaneously verifying the existence of gravitational waves predicted by Einstein’s general theory of relativity and providing strong evidence favoring inflation. Suspiciously, though, the reported signal was much stronger than expected for most versions of inflation theory. Sure enough, the team’s analysis had not properly accounted for dust in space that skewed the data. Primordial gravitational waves remain undiscovered, though their more recent cousins, produced in cataclysmic events like black hole collisions, have been repeatedly detected in recent years.

6. A one-galaxy universe

In the early 20th century, astronomers vigorously disagreed on the distance from Earth of fuzzy cloudlike blobs shaped something like whirlpools (called spiral nebulae). Most astronomers believed the spiral nebulae resided within the Milky Way galaxy, at the time believed to comprise the entire universe. But a few experts insisted that the spirals were much more distant, themselves entire galaxies like the Milky Way, or “island universes.” Supposed evidence against the island universe idea came from measurements of internal motion in the spirals. It would be impossible to detect such motion if the spirals were actually way far away. But by 1924, Edwin Hubble established with certainty that at least sone of the spiral nebulae were in fact island universes, at vast distances from the Milky Way. Those measurements of internal motion were difficult to make — and they just turned out to be wrong.

5. A supernova’s superfast pulsar

Astronomers rejoiced in 1987 when a supernova appeared in the Large Magellanic Cloud, the closest such stellar explosion to Earth in centuries. Subsequent observations sought a signal from a pulsar, a spinning neutron star that should reside in the middle of the debris from some types of supernova explosions. But the possible pulsar remained hidden until January 1989, when a rapidly repeating radio signal indicated the presence of a superspinner left over from the supernova. It emitted radio beeps nearly 2,000 times a second — much faster than anybody expected (or could explain). But after one night of steady pulsing, the pulsar disappeared. Theorists raced to devise clever theories to explain the bizarre pulsar and what happened to it. Then in early 1990, telescope operators rotated a TV camera (used for guiding the telescope) back into service, and the signal showed up again — around a different supernova remnant. So the supposed signal was actually a quirk in the guide camera’s electronics — not a message from space.

4. A planet orbiting a pulsar

In 1991, astronomers reported the best case yet for the existence of a planet around a star other than the sun. In this case, the “star” was a pulsar, a spinning neutron star about 10,000 light-years from Earth. Variations in the timing of the pulsar’s radio pulses suggested the presence of a companion planet, orbiting its parent pulsar every six months. Soon, though, the astronomers realized that they had used an imprecise value for the pulsar’s position in the sky in such a way that the signal anomaly resulted not from a planet, but from the Earth’s motion around the sun.

3. Age of Earth

In the 1700s, French naturalist Georges-Louis Leclerc, Comte de Buffonestimated an Earth age of about 75,000 years, while acknowledging it might be much older. And geologists of the 19th century believe it to be older still — hundreds of millions of years or more — in order to account for the observation of layer after layer of Earth’s buried history. After 1860, Charles Darwin’s new theory of evolution also implied a very old Earth, to provide time for the diversity of species to evolve. But a supposedly definite ruling against such an old Earth came from a physicist who calculated how long it would take an originally molten planet to cool. He applied an age limit of about 100 million years, and later suggested that the actual age might even be much less than that. His calculations were in error, however — not because he was bad at math, but because he didn’t know about radioactivity.

Radioactive decay of elements in the Earth added a lot of heat into the mix, prolonging the cooling time. Eventually estimates of the Earth’s age based on rates of radioactive decay (especially in meteorites that formed around the same time as the Earth) provided the correct current age estimate of 4.5 billion years or so.

2. Age of the universe

When astronomers first discovered that the universe was expanding, at the end of the 1920s, it was natural to ask how long it had been expanding. By measuring the current expansion rate and extrapolating backward, they found that the universe must be less than 2 billion years old. Yet radioactivity measurements had already established the Earth to be much older, and it was very doubtful (as in impossibly ridiculous) that the universe could be younger than the Earth. Those early calculations of the universe’s expansion, however, had been based on distance measurements relying on Cepheid variable stars.

Astronomers calculated the Cepheids’ distances based on how rapidly their brightness fluctuated, which in turn depended on their intrinsic brightness. Comparing intrinsic brightness to apparent brightness provided a Cepheid’s distance, just as you can gauge the distance of a lightbulb if you know its wattage (oh yes, and what kind of lightbulb it is). It turned out, though, that just like lightbulbs, there is more than one kind of Cepheid variable, contaminating the expansion rate calculations. Nowadays converging methods give an age of the universe of 13.8 billion years, making the Earth a relative newcomer to the cosmos.

1. Earth in the middle

OK, we’re going to name and blame Aristotle for this one. He wasn’t the first to say that the Earth occupies the center of the universe, but he was the most dogmatic about it, and believed he had established it to be incontrovertibly true — by using logic. He insisted that the Earth must be in the middle because earth (the element) always sought to move toward its “natural place,” the center of the cosmos. Even though Aristotle invented formal logic, he apparently did not notice a certain amount of circularity in his argument. It took a while, but in 1543 Copernicus made a strong case for Aristotle being mistaken. And then in 1610 Galileo’s observation that Venus went through a full set of phases sealed the case for a sun-centered solar system.

Now, it would be nice if there were a lesson in this list of errors that might help scientists do better in the future. But the whole history of science shows that such errors are actually unavoidable. There is a lesson, though, based on what the mistakes on this list have in common: They’re all on a list of errors now known to be errors. Science, unlike certain political philosophies and personality cults, corrects its mistakes. That’s the lesson, and that’s why respecting science is so important to avoiding errors in other realms of life.

It was one of those “big, if true” stories. In September, scientists reported that Venus’ atmosphere seems to be laced with phosphine, a possible sign of life.

Now there’s increasing emphasis on the “if.” As scientists take fresh looks at the data behind the Venus announcement, and add other datasets to the mix, the original claim of inexplicable amounts of phosphine is being called into doubt. And that’s a good thing, many scientists say.

“It’s exactly how science should work,” says planetary scientist Paul Byrne of North Carolina State University in Raleigh, who studies Venus but was not involved in any of the phosphine papers. “It’s too early to say one way or the other what this detection means for Venus.”

Here’s a closer look at efforts to get from “if” to “true:”

The big claim

On September 14, astronomer Jane Greaves of Cardiff University in Wales and colleagues reported that they had seen signs of phosphine in Venus’ clouds using two different telescopes (SN: 9/14/20). The phosphine seemed to be too abundant to exist without some kind of source replenishing it. That source could be strange microbes living in the clouds, or some weird unknown Venusian chemistry, the team said.

Greaves and colleagues first spotted phosphine with the James Clerk Maxwell Telescope in Hawaii and followed up with the powerful ALMA telescope array in Chile. But those ALMA data, and particularly the way they were handled, are now being called into question.

Reading the data: Real molecules or random wiggles?

The key Venus observations were spectra, or plots of the light coming from the planet in a range of wavelengths. Different molecules block or absorb light at specific wavelengths, so searching for dips in a spectrum can reveal the chemicals in a planet’s atmosphere.

Phosphine showed up as a dip in Venus’ spectrum at about 1.12 millimeters, a wavelength of light that the molecule was thought to be absorbing. If Venus’ spectrum could be drawn as a straight line across all wavelengths of light, phosphine would make a deep valley at that wavelength.

But real data are never that easy to read. In real life, other sources — from Earth’s atmosphere to the inner workings of the telescope itself — introduce wiggles, or “noise,” into that nice straight line. The bigger the wiggles, the less scientists believe that the dips represent interesting molecules. Any particular dip might instead be just a random, extra-large wiggle.

That problem gets even worse when looking at a bright object such as Venus with a powerful telescope like ALMA, says Martin Cordiner, an astrochemist at NASA’s Goddard Space Flight Center in Greenbelt, Md. Cordiner uses ALMA to observe other objects in the solar system, like Saturn’s moon Titan, but was not involved in the Venus work.

“The reason those bumps and wiggles are here at all is because of the intrinsic brightness of Venus, which makes it difficult to get a reliable measurement,” Cordiner says. “You could think of it as being dazzled by a bright light: If there’s a bright light in your vision, then your ability to pick out fainter details becomes diminished.”

So astronomers do a few different things to smooth out the data and let real signals shine through. One strategy is to write an equation that describes the wiggles caused by the noise. Scientists can then subtract that equation from the data to highlight the signal they’re interested in, like fuzzing out the background of a photo to let a portrait subject pop. That’s a standard practice, says Cordiner.

But it’s possible to write an equation that fits the noise too well. The simplest equation one could use is just a straight line, also known as a first-order polynomial, described by the equation y=mx+b. A second-order polynomial adds a term with x squared, third-order with x cubed, and so on.

Greaves and colleagues used a twelfth-order polynomial, or an equation with twelve terms (plus a constant, the +b in the equation), to describe the noise in their ALMA data.

“That was a red flag that this needed to be looked at in more detail, and that the results of that polynomial fitting could be untrustworthy,” says Cordiner. Going all the way out to the power of 12 could mean a researcher subtracts more noise than is truly random, allowing them to find things in the data that aren’t really there.

To see if the researchers were a little overzealous in their polynomial fitting, astrophysicist Ignas Snellen, of Leiden University in the Netherlands, and colleagues reapplied the same noise reduction recipe to the ALMA data on Venus and found no statistically significant sign of phosphine, they report in a paper posted at arXiv.org on October 19.

Then the researchers tried the same noise filtering on other parts of Venus’ spectrum, where no interesting molecules should be found. They found five different signals of molecules that aren’t really there.

“Our analysis … shows that at least a handful of spurious features can be obtained with their method, and therefore [we] conclude that the presented analysis does not provide a solid basis to infer the presence of [phosphine] in the Venus atmosphere,” the team wrote.

Looking for other data — and getting no help yet

Meanwhile, scientists at ALMA discovered a separate, unspecified issue in the data that were used to detect the phosphine and took those data off the observatory’s public archive to scrutinize and reprocess, according to a statement from the European Southern Observatory, of which ALMA is a part.

“This does not happen very often,” says Martin Zwaan of the ESO ALMA Regional Center in Garching, Germany, but this isn’t a first. When issues are discovered, it is standard practice to reprocess the data. “In many cases, it does not affect the science outcome significantly,” Zwaan says. “In the case of the phosphine on Venus, this [outcome] has not been established yet.”

What can scientists do while they wait? One of the best ways to confirm the phosphine is to see an equivalent signal at a different wavelength in Venus’ spectrum. Unfortunately, the news isn’t great there either. In a paper to appear in Astronomy & Astrophysics, astronomer Thérèse Encrenaz of the Paris Observatory and colleagues (including Greaves and some other authors of the original paper) looked at archived data from an infrared spectrograph called TEXES that operates in Hawaii. Those observations could have spotted phosphine in Venus’ cloud tops, a lower part of the sky than what ALMA could see.

Greaves and colleagues had approached Encrenaz to look for phosphine in infrared wavelengths before the original paper came out, but those observations were cancelled by the COVID-19 pandemic. So Encrenaz looked through data she had collected between 2012 and 2015 — and found nothing.

“At the level of the cloud tops, there is no [phosphine] at all,” Encrenaz says. That doesn’t necessarily mean there’s no phosphine higher up in the sky — there’s just no clear explanation for how it would get there. “The reasoning in the paper by Jane Greaves was that phosphine was coming from the clouds,” Encrenaz says. “So there is a big problem.”

‘This is just what science looks like.’

There are still ways for Venus’ phosphine to pull through. If it varies with time, for instance, it might be there some of the times that astronomers look and not at others. It’s too early to invoke that scenario, though, Cordiner says. “There’s no point of talking about the time variability of a signal if it isn’t there.”

But this is not a crisis, says Clara Sousa-Silva, an astrochemist at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., and a coauthor of the original paper. Other groups challenging the finding “is completely normal and what I expected (nay, hoped) would happen,” she wrote in an e-mail. “This is usually a phase of a project that I enjoy, and I am hoping people will realize this is just what science looks like.”

The silver lining in all of this is that it’s gotten people excited about Venus, says Byrne, who is a member of NASA’s Venus Exploration Analysis Group.

“These papers provide much value and a needed assessment of these extraordinary claims,” he says. “If nothing else, it has shone a light on just how little we understand about Venus. And the only way we get those answers is if we go to Venus.”

There’s nothing Winifred Frick likes better than crawling through guano-filled caves and coming face-to-face with bats. As chief scientist of Bat Conservation International, she is on a mission to promote understanding of bats and protect imperiled species from extinction.

For months, though, Frick has avoided research that would put her within spitting distance of bats. Her only projects to persist through the pandemic have been conducted from afar, like using acoustic monitors to eavesdrop on the animals’ squeaks and swooshes. In an era of COVID-19, that “hands-off” approach and other precautions are crucial to protect both bats and people, Frick, a biologist at the University of California, Santa Cruz, and over two dozen other scientists argue online September 3 in PLOS Pathogens.

Why the call to action? SARS-CoV-2, the virus that causes COVID-19, likely originated in bats in China (SN: 3/26/20). But neither it nor other coronaviruses belonging to the same genus — Betacoronavirus — have been detected in the more than 40 bat species in North America, although the animals do harbor other types of coronaviruses. Scientists are not worried about catching SARS-CoV-2 from these bats. They’re afraid of giving it to the bats — not an impossibility, the authors argue, given that the United States leads the world in infections, with nearly 8 million as of October 16.

“We can’t tell bats to socially distance,” Frick says. “We want to reduce the chance that there’s any pathogen transfer across animals, full stop.” The goal is to prevent viral “spillover.”

Human-to-bat transmission isn’t an unheard-of scenario. People are likely to blame for introducing Pseudogymnoascus destructans, the fungus that causes white nose syndrome, to North American bats. The disease has killed millions of bats throughout the United States and Canada since it was first detected in 2006 (SN: 3/31/16).

It’s unknown if bats are susceptible to SARS-CoV-2 infection, or if the virus would make them sick — bats rarely become ill from the viruses they carry (SN: 2/12/20). But infected bats might spread the virus back to humans, the authors say.

Worse, introducing SARS-CoV-2 to other coronaviruses carried by North American bats could provide the ingredients for creating a new virus (SN: 11/30/17). Either scenario could stoke pre-existing fears about bats spreading disease, presenting a major hurdle for bat conservationists trying to bolster support for the animals.

The International Union for the Conservation of Nature’s bat specialist group, which includes Frick, initially advocated for the hands-off approach in April. Because so little was known in the early days of the pandemic about how SARS-CoV-2 spreads, that group recommended that researchers shut down any projects that involved interacting with bats. In August, the group updated its guidelines to also address spelunking and other activities that might bring humans into bat habitat.

The guidelines still recommend replacing fieldwork with distanced alternatives whenever possible. Picking through guano can identify bat species and reveal the viruses they carry, and cameras positioned outside bat caves and roosts can give a sense of abundance. Scientists can even resurrect evidence of pathogens held in the preserved tissues of bat specimens in museums.

But not all bat research can be socially distanced, and that means taking pandemic precautions, like ensuring field crews aren’t sick with COVID-19 and are wearing personal protective gear. White nose syndrome research already requires disposable Tyvek suits and gloves to reduce spreading the fungus. Now, masks will be a regular part of the ensemble.

For Frick, speaking up for bats has always been a part of being a bat biologist. Besides having a passion for the animals, conservation and human health are inseparable, she says. And bats provide ecosystem services that benefit humans, like pest control that saves North American farmers more than an estimated $3.7 billion per year, according to a study published in 2011 in Science. As human populations expand into shrinking bat habitat, bats and humans increasingly cross paths, making viral spillover events and other harmful interactions more likely. The pandemic has intensified those risks, and for Frick, put the need to speak up “on steroids now.”

Great Adaptations
Kenneth Catania
Princeton Univ., $27.95

Neurobiologist Kenneth Catania’s passion for scrutinizing odd animal adaptations all started with a creature with a 22-point star on its face.

Catania first saw a star-nosed mole (Condylura cristata) in a children’s book. Later as a 10-year-old, he found a dead one near a stream close to his home in Columbia, Md. From then on, he kept his eyes peeled for more. He had to wait until he was in college, when he landed a research position that required him to trap star-nosed moles in Pennsylvania’s wetlands. At the time, no one knew what that unique nose was good for, and he wanted to figure it out.

In Great Adaptations, Catania describes his pursuit of the mystery behind the mole’s wiggly star-shaped appendage (it helps the subterranean animal sense prey without using sight) as well as a slew of other animal tricks. The account of his adventures as a biological sleuth provides a detailed look at curiosities such as how “hangry” water shrews execute the fastest documented predatory attack by a mammal and how cockroaches resist becoming zombies during parasitoid wasp attacks (SN: 10/31/18).

“It’s part of human nature to be intrigued by mysteries, but the mystery only gets us to the door,” he writes. “You never know what you might find on the other side.”

In search of answers, Catania has set up some odd, but amusing, experiments. To film wasps attacking cockroaches, he built a set fit for a horror flick, by filling a tiny kitchen with warning signs and a plastic human skull for the wasp to store its zombified victim in. Keeping with the horror theme, he also stripped the paint off decorative severed zombie arms and offered the plastic limbs to electric eels (Electrophorus electricus) to show that the animals leap out of the water as an attack strategy (SN: 6/9/16).

Each chapter follows a logical flow as Catania describes his discoveries, from what first piqued his interest in an animal to his ultimate findings. Science, however, is rarely as straightforward as he makes it seem. Catania’s scientific detective work didn’t always go off without a hitch, but, he notes, including all the failures would have meant a much longer book. Even so, the book alludes to some ideas that didn’t pan out. “The animals are always able to do something unexpected and more interesting than I’d imagined,” he writes.

For instance, the notion that a tentacled snake (Erpeton tentaculatum) might use the short appendages close to itsmouth to lure in nearby fish, just like snapping turtles dowith their tongues, turned out to be wrong. Instead, the tentacleshelp a snake sense a fish’s position in the water andknow when to attack. What’s more, the snakes have hackedtheir prey’s natural escape reflexes. In a fatal mistake, fishflee in the wrong direction — straight toward a snake’smouth — when duped by a twitch of the snake’s neck rightbefore the predator strikes.

Catania’s lighthearted yet informative narrative presents science in a way that’s easy for anyone with a basic knowledge of biology to understand. But even the most seasoned expert will likely learn new details, the type that never make it into a scientific paper. For a particularly daring experiment, in which Catania offered his own arm for an electric eel’s shock to measure the shock’s electricity, Catania admits that he certainly couldn’t subject another animal or a student volunteer to the unpleasant jolt (SN: 9/14/17). His own arm was the “obvious solution.”

In page after page, Catania’s enthusiasm and awe for the animals shine through. When he discovered tentacled snakes are born knowing how to strike at prey rather than learning through failure, Catania recalls that he couldn’t “find enough superlatives to sum up these results.” He also describes a fight between a parasitoid wasp and a cockroach as an “insect rodeo.” The wasp attacks a cockroach’s head in an attempt to lay an egg, but in defense the roach “bucks, jumps, and flails with all its might.”

Some of that enthusiasm will likely rub off on readers and spark a sense of wonder. Great Adaptations packs in plenty of astounding details about some remarkable creatures. As Catania puts it: “I’ve stopped assuming I know the limits of animal abilities.”

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