Photons are caught behaving like superconducting electrons

Light is a fan of the buddy system. Photons, or particles of light, have been spotted swapping energy with partners. This chummy behavior resembles how electrons pair up in materials that conduct current without resistance, known as superconductors, researchers report in a paper accepted in Physical Review Letters.

Although the photons exchange energy like electrons do, it’s unknown whether the particles are actually bound together as electrons are, and whether photons could produce an effect analogous to superconductivity. “This is a door that is opened,” says study coauthor Ado Jorio, a physicist at the Universidade Federal de Minas Gerais in Brazil. Now, he says, the questions that must be addressed are, “How far can we push this similarity? Can we find with photons incredible results like we find for electrons?”
In certain solid materials cooled to extremely low temperatures, electrons form partnerships called Cooper pairs (SN: 6/13/15, p. 8), which allow superconductivity to occur. Although the negatively charged particles typically repel one another, two electrons can bind together by exchanging phonons, or quantum packets of vibration, via the lattice of ions within these materials. This alliance coordinates the electrons’ movements and thereby eases their passage through the material, allowing them to flow without resistance. Superconductivity’s potential technological applications — which include energy-efficient power transmission, superstrong magnets and levitating trains — have attracted heaps of scientific interest in the phenomenon.

Now, Jorio and colleagues have shown photons behaving similarly to superconducting electrons. When the researchers shined a laser on water, pairs of photons that emerged from the liquid at the same time tended to have complementary energies. While one photon had lost a little energy, another had gained the same amount of energy, indicating that they were exchanging quantum vibrations. The effect appeared in a variety of transparent materials, says Jorio, and it was observed at room temperature, unlike electron pairing in superconductors.

The team also showed that the exchanged quantum vibrations were “virtual” — appearing only for fleeting moments — just like the vibrations exchanged by electrons. The theory that explains the interaction “is exactly the same as for the electrons,” Jorio says.

Scientists already knew that photons can lose or gain energy via vibrations, but the similarity with Cooper pairs is a new and interesting way of thinking about the effect, says physicist Ian Walmsley of Oxford University, who was not involved with the research. “It’s a field that has not yet been explored.”
It is still too early to know how far the analogy with superconducting electrons extends, says physicist Ben Sussman of the National Research Council of Canada in Ottawa, who was not involved with the research. But the connection seems worth investigating: “This is an interesting rabbit hole indeed.”

Scary as they are, few vampires have a backbone

Halloween horror aside, vampires are really pretty spineless.

Most have no backbone at all. By one count, some 14,000 kinds of arthropods, including ticks and mosquitoes, are blood feeders. Yet very few vertebrates are clear-cut, all-blood specialists: just some fishes and three bats. Why hasn’t evolution produced more vertebrate vampires?

The question intrigues herpetologist Harry Greene of Cornell University, who “can’t think of a single example among amphibians and reptiles,” he says. (Some birds are opportunists, sneaks or outright meat eaters, but they don’t have the extreme specialization of bats.)
Kurt Schwenk of the University of Connecticut in Storrs, who studies feeding morphology, comes up empty, as well. As he muses over what animals might have precursor biology that could lead to blood feeding, “a leechlike or lamprey-like blood-sucking tadpole should be a real possibility,” he says. The idea gives him “the heebie-jeebies,” but some tadpole species have already evolved mouths that can cling, and plenty of tadpoles are carnivorous.
Looking at the question from a different point of view — asking what would favor, or not, the evolution of blood feeding—he comes up with a less disturbing answer. For carnivorous animals, eating meat is nutritionally better than sipping blood alone, he says. So vampirism might not offer much of an advantage. “If you don’t need to be light and you’re not a parasite,” he says, there’s “no point in limiting yourself to blood.” So maybe vampiric tadpoles aren’t part of some creepy future after all.
Some adult fishes have evolved blood feeding, even mainstream vertebrates with jaws and bones (unlike cartilage-only jawless lampreys). Among the clear-cut bony examples are some Vandellia canidru catfishes, which fasten onto a gill of a much larger fish and let the fish heart pump sustenance into them as they nestle inside the protected gill chamber. (This is different from the supposed, or maybe mythical, tendency of some canidru catfishes to misunderstand fluid streams and swim up the urethras of humans in the water.)

Among vertebrates, vampirism inside or outside of gills might have arisen from ancestors that hitchhiked on big fishes and nibbled off parasites, in the same way modern remoras (also known as suckerfish) do, suggests parasitologist Tommy Leung of the University of New England in Armidale, Australia. Biologists already know about parasite-picker species, such as some cleaner fish, that will cheat and nip mucus or scales if they can get them. Actual blood-sucking cheats could be mere geologic ages away from that evolutionary step. Vertebrates may have relatively few vampires, but a greater number of almost-vampires.

Full-scale vampirism “is a tough way to make a living,” says William Schutt of Long Island University in Brookville, NY, and author of a book on the topic, Dark Banquet. But also, he adds, one big reason why there are fewer vertebrate vampires than arthropod bloodsuckers may be in the numbers. There are just fewer vertebrates: an estimated 60,000 versus a whopping 10 million arthropods.

These spiders may have the world’s fastest body clocks

WASHINGTON, D.C. — If it takes you a while to recover from a few lost hours of sleep, be grateful you aren’t an orb weaver.

Three orb-weaving spiders — Allocyclosa bifurca, Cyclosa turbinata and Gasteracantha cancriformis — may have the shortest natural circadian rhythms discovered in an animal thus far, researchers reported November 12 at the Society for Neuroscience’s annual meeting.

Most animals have natural body clocks that run closer to the 24-hour day-night cycle, plus or minus a couple hours, and light helps reset the body’s timing each day. But the three orb weavers’ body clocks average at about 17.4, 18.5 and 19 hours respectively. This means the crawlers must shift their cycle of activity and inactivity — the spider equivalent of wake and sleep cycles — by about five hours each day to keep up with the normal solar cycle.
“That’s like flying across more than five time zones, and experiencing that much jet lag each day in order to stay synchronized with the typical day-night cycle,” said Darrell Moore, a neurobiologist at East Tennessee State University in Johnson City.

“Circadian clocks actually keep us from going into chaos,” he added. “Theoretically, [the spiders] should not exist.”

For most animals, internal clocks help them perform recurring daily activities, like eat, sleep and hunt, at the most appropriate time of day. Previous studies have shown that animals that are out of sync with the 24-hour solar cycle are usually less likely to produce healthy offspring than those that aren’t.
Moore and his colleagues were surprised to find the short circadian clocks while studying aggression and passivity in an orb weaver. The team was trying to see if there was a circadian component to these predatory and preylike behaviors, when they discovered C. turbinata’s exceptionally short circadian cycles. “I was looking at this thing thinking, ‘That can’t be right,’” said Moore.

To measure spiders’ natural biological clocks without the resetting effect of the sun, the researchers placed 18 species of spiders in constant darkness and monitored their motion. Three orb weaver species in particular had incredibly short cycles of activity and inactivity.

As far as the researchers know, the short cycle does not seem to be a problem for these spiders. In fact, it might even be useful. Short clocks may help these orb weavers avoid becoming the proverbial “worm” to the earliest birds, the researchers hypothesize. Since the spiders become more active at dusk and begin spinning their webs three to five hours before dawn, they can avoid predators that hunt in the day.

Throughout the day, the spiders remain motionless on their web, prepared to pounce on their next meal. By midday, the spiders’ truncated circadian clocks should have reset, sparking a new round of activity. But in the five to seven hours of daylight left, the orb weavers remain inactive. It’s hard to say whether the spiders are actually resting, Moore said. The researchers suspect that light may delay the onset of another short circadian cycle each day, helping the spiders stay synchronized with the 24-hour environmental cycle.

“The method or molecular mechanism will be really fascinating to figure out,” said Sigrid Veasey, a neuroscientist at the University of Pennsylvania’s Perelman School of Medicine. She is curious to know how the spiders can be so far off from “normal” circadian periods, and still be able to match their activity to the 24-hour light and dark cycle.

Determining the differences between short and normal period clocks in spiders may help researchers find out why and how different circadian clocks are suited to the particular environmental challenges of each species, Moore said.

New setup for image recognition AI lets a program think on its feet

Artificial intelligence is getting some better perspective. Like a person who can read someone else’s penmanship without studying lots of handwriting samples, next-gen image recognition AI can more easily identify familiar sights in new situations.

Made from a new type of virtual building block called capsules, these programs may cut down the enormous amount of data needed to train current image-identifying AI. And that could boost such technology as machine-made medical diagnoses, where example images may be scarce, or the responsiveness of self-driving cars, where the view is constantly shifting. Researchers with Google will present this new version of an artificial neural network at the Neural Information Processing Systems conference in Long Beach, Calif., on December 5.
Neural networks are webs of individual virtual nerve cells, or neurons, that learn to pick out objects in pictures by studying labeled example images. These networks largely classify pictures based on whether they contain certain features. For instance, a program trained on a series of head shots might conclude that a face has two eyes, a nose and a mouth. Show that program a face in profile with only one eye visible, though, and it may not recognize the photo as a face, explains Roland Memisevic, a computer scientist at the University of Montreal who was not involved in the work.

To overcome that limitation, researchers can train a neural network on millions of photos from myriad angles, and the program memorizes all the different ways a face might look. Compared with the human brain, which doesn’t need anywhere near a million examples to know what a face looks like, this system is wildly inefficient. “It’s a disaster,” Memisevic says. “Capsules try to fix that.”

Instead of webs of individual artificial neurons, these new programs have webs of clusters of neurons, called capsules. These teams of neurons can provide more information than one neuron by itself. Each capsule is designed to track not only whether a certain feature is in an image, but also properties of that feature — say, a nose’s size, orientation and position. This spatial awareness helps the program better recognize objects in previously unseen scenarios.

A capsule-containing network trained on head shots could see a face in profile and deduce — based on the appearance of the visible eye, nose and mouth — that the other eye is simply obscured, and the picture depicts a face. Since capsule networks are better at applying what they know to new situations, these neural networks need less training data to achieve the same performance as their predecessors, says Sara Sabour, a computer scientist with Google Brain in Toronto.
Sabour and her colleagues trained one capsule network on images of handwritten numbers and tested it on pictures where each number was slightly distorted. The capsule network recognized the warped images with 79 percent accuracy; a typical neural network trained on the same amount of data only got 66 percent right.

In another experiment, Sabour and colleagues trained a similar capsule network on tens of thousands of photos of toys, and then asked it to recognize the toys from new viewpoints. In this challenge, reported in a paper submitted to the 2018 International Conference on Learning Representations in Vancouver, the capsule network was wrong only about 1.4 percent of the time. A conventional neural network made almost twice as many errors.

Mini brains may wrinkle and fold just like ours

PHILADELPHIA — Flat brains growing on microscope slides may have revealed a new wrinkle in the story of how the brain folds.

Cells inside the brains contract, while cells on the outside grow and push outward, researchers at the Weizmann Institute of Science in Rehovot, Israel, discovered from working with the lab-grown brains, or organoids. This push and pull results in folds in the organoids similar to those found in full-size brains. Orly Reiner reported the results December 5 at the joint meeting of the American Society for Cell Biology and the European Molecular Biology Organization.
Reiner and her colleagues sandwiched human brain stem cells between a glass microscope slide and a porous membrane. The apparatus allowed the cells access to nutrients and oxygen while giving the researchers a peek at how the organoids grew. The cells formed layered sheets that closed up at the edges, making the organoids resemble pita bread, Reiner said. Wrinkles began to form in the outer layers of the organoids about six days after the mini brains started growing.

These brain organoids may help explain why people with lissencephaly — a rare brain malformation in which the ridges and folds are missing — have smooth brains. The researchers used the CRISPR/Cas9 gene-editing system to make a mutation in the LIS1 gene. People with lissencephaly often have mutations in that gene. Cells carrying the mutation didn’t contract or move normally, the team found.

Reiner and her colleagues aren’t the first to propose the push-pull idea for how brains fold. But the researchers were able to show the concept at work in their experimental system, says biophysicist Xavier Trepat of the Institute for Bioengineering of Catalonia in Barcelona, who was not involved in the study. “They really were able to reproduce the shape of what we all imagine the brain should look like,” he says. “It’s not a brain, but they see structures that look like it.”

U.S. religion is increasingly polarized

There’s both inspiring and troubling news for holiday worshippers.

Unlike other historically Christian Western nations, the United States is not losing its religion, say sociologists Landon Schnabel of Indiana University Bloomington and Sean Bock of Harvard University. But America is becoming as polarized religiously as it is politically, the researchers report online November 27 in Sociological Science.

Intense forms of religion, such as Christian evangelicalism, have maintained their popularity for nearly 30 years, Schnabel and Bock find after analyzing almost 30 years of U.S. survey data. At the same time, moderate forms of religion, such as mainline Protestantism, have consistently lost followers.
Religious moderates’ exodus from their churches stems partly from a growing link between religion and conservative politics, exemplified by the rise of the religious right in the late 1980s, the researchers suspect. Political liberals and moderates who already felt lukewarm toward the religion of their parents increasingly report identifying with no organized religion, especially if leaders of their childhood churches have taken conservative stances on social issues. Many Americans still report that they believe in God and pray, so they haven’t turned to atheism, the scientists say.

Population trends also favor intense forms of religion, Schnabel holds. Mainline Protestantism’s decline from 35 percent of the U.S. population in 1972 — about 73.5 million people — to 12 percent in 2016 — nearly 39 million people — reflects low fertility rates among these Protestants and limited numbers of new adherents from immigration and conversion. Opposite trends among U.S. evangelicals helped their form of intense Christianity surge from 18 percent of the population in 1972 to a steady level of about 28 percent from 1989 to 2016.

“More moderate forms of organized religion could become increasingly irrelevant in the United States,” Schnabel says.
The new findings play into an academic debate about the fate of religion in modern societies. Some scholars argue that in wealthy nations marked by scientific advances, religion inevitably withers. National surveys in 13 other Western, historically Christian nations show a general weakening of religious beliefs, even among intense believers, since 1991, the researchers find. But Schnabel and Bock are among those who view the United States as an exception where intense religion holds steady and even many of those leaving churches keep their faith.

The researchers examined data from nationally representative surveys on religion and other topics conducted from 1989 to 2016 by the General Social Survey, or GSS, a project of the National Opinion Research Center at the University of Chicago. GSS surveys include approximately 1,500 people annually.

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The proportion of the U.S. population citing strong ties to any religion held steady at around 36 percent during the study period. But the share of adults identifying themselves as religiously unaffiliated rose from around 9 percent to around 20 percent of the population, the researchers report. In another sign of loosening religious ties, those who never attended religious services rose from around 14 percent to around 25 percent of the population. Occasional attendance dropped from about 80 percent to about 70 percent.

Still, those who rarely or never prayed remained at about 24 percent of the population from 1989 to 2016. People who prayed several times a day rose from around 24 percent to about 30 percent of the total.

A belief in the Bible as God’s literal word held steady at roughly one-third of Americans. A view of the Bible as inspired by a higher power but not literal fell slightly to just under half of the population. Those tagging the Bible as a book of fables rose from around 15 percent to around 22 percent.

The new findings underscore the growing polarization of U.S. religion, say Michael Hout of New York University and Claude Fischer of the University of California, Berkeley. In a 2014 report based on GSS data, the two sociologists found that most political liberals and some political moderates who weakly identified with their parents’ religion have increasingly said that they prefer no particular religion. That trend was most pronounced for those reporting that the church they grew up with had become an advocate of politically conservative positions. Many of those people expressed a qualified belief in God, endorsing neither atheism nor absolute certainty in a higher power’s existence. Political conservatives, including those who seldom attended services or had doubts about church doctrine, had no complaints about religious leaders’ conservative political pronouncements.

Members of the millennial generation born since 1990 report low levels of religious involvement regardless of their politics, Hout adds. Millennials are skeptical of institutions in general although most still believe in God, he says. “Millennials are more comfortable with do-it-yourself religion than none at all.”

Sociologists David Voas of University College London and Mark Chaves of Duke University disagree. Millennials are part of a larger U.S. trend in which each successive generation over nearly the last century has reported slightly less intensity of religious belief than the one before, Voas and Chaves reported in a 2016 analysis of GSS data. For instance, in 2014, only 45 percent of U.S. adults ages 18 to 30 had no doubts that God exists versus 68 percent of those age 65 or over.

“The proportion of intensely religious Americans is being eroded, albeit very slowly,” Voas contends.

The sun’s outer atmosphere is far more complex than previously thought

NEW ORLEANS — Despite its smooth appearance, the sun’s wispy outer atmosphere is surprisingly full of knots, whorls and blobs.

Newly analyzed observations from NASA’s STEREO spacecraft show that the sun’s outer corona is just as complicated as the highly structured inner corona, solar physicists reported December 12 at the fall meeting of the American Geophysical Union. That previously unseen structure could help solve some of the sun’s biggest puzzles, including how the solar wind is born and why the corona is so much hotter than the solar surface.
The corona is made up of charged plasma, which roils in famous loops and fans that follow magnetic field lines emerging from the surface of the sun (SN Online: 8/17/17). At a certain distance from the sun, though, that plasma escapes the corona and streams through the solar system as the solar wind, a constant flow of charged particles that pummels the planets, including Earth (SN Online: 8/18/17).

But solar physicists don’t know where the plasma gets enough energy to accelerate away from the massive, magnetic sun. And they don’t understand why the corona, which sizzles at several million degrees Celsius, has such higher temperatures than the solar surface, which chills at a mere 5,500° C (SN Online: 8/20/17).

Both problems might be cleared up by better understanding an energetic process called reconnection, which happens when magnetic field lines merge when they get too close to each other. Reconnection releases energy and helps move plasma around, so the process could be important to heating the corona and driving solar wind.

But in the best observations until now, the outer corona appeared smooth and uniform. To explain that smoothness, field lines would have to keep their distance from each other without a lot of reconnection. What’s more, physicists couldn’t tell where the boundary between the corona and the solar wind began, which might help to find that missing energy source.
“That’s changed,” solar physicist Craig DeForest of the Southwest Research Institute in Boulder, Colo., said at the AGU meeting. “Using STEREO, we’ve recently been able to drill in deeply enough to see the transition at the outer edge of the corona, where the dynamics change from what we might call coronal plasma to what we might call the young solar wind plasma.”

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DeForest and colleagues collected data for three days with STEREO in 2014 to gain more detail about small-scale changes in the outer corona than previously obtained. The researchers also processed the resulting images in a new way to bring those changes into focus.

Surprisingly, the team found that the outer corona is full of moving blobs and fine streams of plasma that vary in density by a factor of 10, suggesting that the magnetic field lines there are moving and merging more than scientists thought. “It turns out the apparent smoothness is a reflection of our instruments, not the corona itself,” DeForest says. “There’s almost certainly reconnection in the outer corona.”

The researchers also found that the corona probably fades into the solar wind between 14 million and 56 million kilometers away from the sun — about 10 to 40 times the sun’s diameter. That’s still a big range, but NASA’s Parker Solar Probe spacecraft, scheduled to launch in 2018, will fly right through that boundary. The probe will swoop within 6.4 million kilometers of the sun and take the first direct measurements of the corona — and perhaps figure out more precisely where the corona becomes the solar wind.

For now, the STEREO observations “are just tantalizing hints at an entire new set of phenomena,” DeForest says. Understanding the details of those processes “is going to require both careful analysis from Parker Solar Probe and also new, better imaging instruments.”

Solar physicist Steven Cranmer of the University of Colorado Boulder, who has made simulations of magnetic reconnection in the outer corona, finds the results exciting. Questions about the sun’s hot corona and the acceleration of the solar wind are still unsolved “not because of a lack of ideas, but because there are too many ideas,” he says. “I think we’re getting close to having the data that will let us rule out a good swath of these proposed ideas.”

The science behind kids’ belief in Santa

Over the past week, my little girls have seen Santa in real life at least three times (though only one encounter was close enough to whisper “yo-yo” in his ear). You’d think that this Santa saturation might make them doubt that each one was the real deal. For one thing, they looked quite different. Brewery Santa’s beard was a joke, while Christmas-tree-lighting Santa’s beard was legit. Add to that variations in outfits and jolliness levels.

But as I delved into the Santa-related research, I found I was wrong to think his omnipresence might throw my kids off. It turns out that the more kids see real, live Santa Clauses, the more likely they are to think he’s real. More exposure actually tracked with stronger belief, scientists reported in Cognitive Development in 2016.

That got me wondering about this belief. Like many parents, I feel a little hint of unease when it comes to telling my trusting, innocent children a lie. But lots of parents conspire to tell this lie to their children. An AP survey from 2011 (the most recent I could find on this pressing issue) revealed that 84 percent of adult respondents believed in Santa as a child.

Many of these former children had their Christmas beliefs shattered around age 8, other studies suggest. A fascinating paper from 1978 found that 85 percent of 4-year-olds believed in Santa. Five percent didn’t, and 10 percent were still thinking about it. But only 25 percent of 8-year-olds believed in Santa, with 20 percent not believing and 55 percent transitioning in their beliefs. Funnily enough, 60 percent of these same 8-year-olds still believed in the tooth fairy.
This shift in belief from age 4 to 8 has some psychology behind it. The influential child psychologist Jean Piaget proposed that around age 8 children enter the “concrete operational stage” of thinking — a critical, observant phase of questioning impossible things. (To be clear, it is impossible for Santa to fly around the world and deliver toys to all the houses, even with the 48 hours he’d have thanks to the Earth’s time zones, and other time-warping assists. Physicists have looked into it.)

Eight-year-olds’ discerning mindset was detected in a study that prodded children to list not toys, but questions for Santa. Young children tended to ask clarifying sorts of questions, such as “Is the North Pole cold?” “What are your elves’ names?” and “What do your reindeer do during the summer?” Those questions get at minor details without coming close to the central mysteries at the heart of a magical Santa. Older kids, however, were more likely to ask the toughies: “How do you fit inside a chimney?” and “How can you see everyone in the whole wide world?”

Once these questions start coming from your kid, the end may be in sight. But take heart, from yet another scientific study of Santa. Children are a sturdy bunch, and do pretty well after they find out the truth, interviews showed. In fact, it’s probably a relief when the entire world stops gaslighting kids and they finally get their hunches confirmed. The bad news is that the parents didn’t fare so well, describing themselves as predominantly sad after their children learned the truth.

For parents, their children’s discovery is an end of an era, a loss of a ritual tied up in family, tradition and treats. But sadder to me, I think, is that when that reckoning comes to my little girls, it will be a vivid reminder that my time with my small children is scant. These moments of magical thinking fly by faster than Santa would need to travel to complete his furious dash around the world.

Ask AI: How not to kill online conversations

A new artificial intelligence could tell whether your next post to an online forum will engage others or fall flat.

Computer scientist Qiaozhu Mei of the University of Michigan in Ann Arbor and colleagues trained a machine-learning program on about 63,000 Reddit threads to learn what dialog-ending responses look like.

This kind of chat-savvy computer code, described in a paper accepted to the 2018 Web Conference in Lyon, France, could someday notify users before they hit “submit” if a post is likely to shut down discussion. Such feedback could lead to more satisfying and productive online conversations.
AI’s guide to being an online conversationalist
Stay on topic. Posts that repeat words used elsewhere in a thread or use more related terms are less likely to end a conversation.

Share experiences. Comments that include words such as “talked,” “heard” or “seen” are liable to incite further discussion.

Keep it moving. The more time that elapses between a post and a reply, the more likely that reply will go unanswered.

Elaborate. Unlike in-person chats, where long monologs can bore those within earshot, lengthier online posts tend to get more responses.

Be polite. Posts that include words like “Mr.” and “Mrs.” are more likely to encourage a back and forth, compared with responses that address people with insulting or intense language, such as curse words or an all-caps “YOU.”

Blowflies use drool to keep their cool

SAN FRANCISCO — Blowflies don’t sweat, but they have raised cooling by drooling to a high art.

In hot times, sturdy, big-eyed Chrysomya megacephala flies repeatedly release — and then retract — a droplet of saliva, Denis Andrade reported January 4 at the annual meeting of the Society for Integrative and Comparative Biology. This process isn’t sweating. Blowfly droplets put the cooling power of evaporation to use in a different way, said Andrade, who studies ecology and evolution at the Universidade Estadual Paulista in Rio Claro, Brazil.
As saliva hangs on a fly’s mouthparts, the droplet starts to lose some of its heat to the air around it. When the fly droplet has cooled a bit, the fly then slurps it back in, Andrade and colleagues found. Micro-CT scanning showed the retracted droplet in the fly’s throatlike passage near the animal’s brain. The process eased temperatures in the fly’s body by about four degrees Celsius below ambient temps. That may be preventing dangerous overheating, he proposed. The same droplet seemed to be released, cooled, drawn back in and then released again several times in a row.

Andrade had never seen a report of this saliva droplet in-and-out before he and a colleague noticed it while observing blowfly temperatures for other reasons. But in 2012, Chloé Lahondère and a colleague described how Anopheles stephensi mosquitoes that exude a liquid droplet that dangles and cools, but at the other end of the animals.

Mosquitoes, which let their body temperatures float with that of their environment, can get a heat rush when drinking from warm-blooded mammals. While drinking, the insects release a blood-tinged urine droplet, which dissipates some of the heat. There’s some fluid movement within the droplet, says Lahondère, now at Virginia Tech in Blacksburg, but whether any of the liquid gets recaptured by the body the way fly drool is, she can’t say.