Biology

novel-camera-system-lets-us-see-the-world-through-eyes-of-birds-and-bees

Novel camera system lets us see the world through eyes of birds and bees

animal perception, animal vision, Biology, cameras, optics, Science / /

A fresh perspective —

It captures natural animal-view moving images with over 90 percent accuracy.

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A new camera system and software package allows researchers and filmmakers to capture animal-view videos. Credit: Vasas et al., 2024.

Who among us hasn’t wondered about how animals perceive the world, which is often different from how humans do so? There are various methods by which scientists, photographers, filmmakers, and others attempt to reconstruct, say, the colors that a bee sees as it hunts for a flower ripe for pollinating. Now an interdisciplinary team has developed an innovative camera system that is faster and more flexible in terms of lighting conditions than existing systems, allowing it to capture moving images of animals in their natural setting, according to a new paper published in the journal PLoS Biology.

“We’ve long been fascinated by how animals see the world. Modern techniques in sensory ecology allow us to infer how static scenes might appear to an animal,” said co-author Daniel Hanley, a biologist at George Mason University in Fairfax, Virginia. “However, animals often make crucial decisions on moving targets (e.g., detecting food items, evaluating a potential mate’s display, etc.). Here, we introduce hardware and software tools for ecologists and filmmakers that can capture and display animal-perceived colors in motion.”

Per Hanley and his co-authors, different animal species possess unique sets of photoreceptors that are sensitive to a wide range of wavelengths, from ultraviolet to the infrared, dependent on each animal’s specific ecological needs. Some animals can even detect polarized light. So every species will perceive color a bit differently. Honeybees and birds, for instance, are sensitive to UV light, which isn’t visible to human eyes. “As neither our eyes nor commercial cameras capture such variations in light, wide swaths of visual domains remain unexplored,” the authors wrote. “This makes false color imagery of animal vision powerful and compelling.”

However, the authors contend that current techniques for producing false color imagery can’t quantify the colors animals see while in motion, an important factor since movement is crucial to how different animals communicate and navigate the world around them via color appearance and signal detection. Traditional spectrophotometry, for instance, relies on object-reflected light to estimate how a given animal’s photoreceptors will process that light, but it’s a time-consuming method, and much spatial and temporal information is lost.

Peacock feathers through eyes of four different animals: (a) a peafowl; (b) humans; (c) honeybees; and (d) dogs. Credit: Vasas et al., 2024.

Multispectral photography takes a series of photos across various wavelengths (including UV and infrared) and stacks them into different color channels to derive camera-independent measurements of color. This method trades some accuracy for better spatial information and is well-suited for studying animal signals, for instance, but it only works on still objects, so temporal information is lacking.

That’s a shortcoming because “animals present and perceive signals from complex shapes that cast shadows and generate highlights,” the authors wrote. ‘These signals vary under continuously changing illumination and vantage points. Information on this interplay among background, illumination, and dynamic signals is scarce. Yet it forms a crucial aspect of the ways colors are used, and therefore perceived, by free-living organisms in natural settings.”

So Hanley and his co-authors set out to develop a camera system capable of producing high-precision animal-view videos that capture the full complexity of visual signals as they would be perceived by an animal in a natural setting. They combined existing methods of multispectral photography with new hardware and software designs. The camera records video in four color channels simultaneously (blue, green, red, and UV). Once that data has been processed into “perceptual units,” the result is an accurate video of how a colorful scene would be perceived by various animals, based on what we know about which photoreceptors they possess. The team’s system predicts the perceived colors with 92 percent accuracy. The cameras are commercially available, and the software is open source so that others can freely use and build on it.

The video at the top of this article depicts the colors perceived by honeybees watching fellow bees foraging and interacting (even fighting) on flowers—an example of the camera system’s ability to capture behavior in a natural setting. Below, Hanley applies UV-blocking sunscreen in the field. His light-toned skin looks roughly the same in human vision and honeybee false color vision “because skin reflectance increases progressively at longer wavelengths,” the authors wrote.

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megalodon-wasn’t-as-chonky-as-a-great-white-shark,-experts-say

Megalodon wasn’t as chonky as a great white shark, experts say

animals, Biology, extinct animals, megalodon, megaototh shark, paleontology, Science / /

Still a pretty impressive size —

Fresh evidence points to megalodon being longer, more slender than previous depictions.

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These are the kinds of shark teeth discovered in burial sites and other ceremonial remains of the inland Maya communities. From left to right, there's a fossilized megalodon tooth, great white shark tooth, and bull shark tooth.

Enlarge / These are the kinds of shark teeth discovered in burial sites and other ceremonial remains of the inland Maya communities. From left to right, there’s a fossilized megalodon tooth, great white shark tooth, and bull shark tooth.

Antiquity

The megalodon, a giant shark that went extinct some 3.6 million years ago, is famous for its utterly enormous jaws and correspondingly huge teeth. Recent studies have proposed that the megalodon was robust species of shark akin to today’s great white sharks, only three times longer. And just like the great white shark inspired Jaws, the megalodon has also inspired a 1997 novel and a blockbuster film (2018’s The Meg)—not to mention a controversial bit of “docu-fiction” on the Discovery Channel.  But now a team of 26 shark experts are challenging the great white shark comparison, arguing that the super-sized creature’s body was more slender and possibly even longer than researchers previously thought in a new paper published in the journal Paleontologia Electronica.

“Our study suggests that the modern great white shark may not necessarily serve as a good modern analogue for assessing at least certain aspects of its biology, including its size,” co-author Kenshu Shimada, a palaeobiologist at DePaul University in Chicago, told The Guardian. “The reality is that we need the discovery of at least one complete megalodon skeleton to be more confident about its true size as well its body form.” Thus far, nobody has found a complete specimen, only fossilized teeth and vertebrae.

As previously reported, the largest shark alive today, reaching up to 20 meters long, is the whale shark, a sedate filter feeder. As recently as 4 million years ago, however, sharks of that scale likely included the fast-moving predator megalodon (formally Otodus megalodon). Due to incomplete fossil data, we’re not entirely sure how large megalodons were and can only make inferences based on some of their living relatives, like the great white and mako sharks.

Thanks to research published last year on its fossilized teeth, we’re now fairly confident that it shared something else with these relatives: it wasn’t entirely cold-blooded and apparently kept its body temperature above that of the surrounding ocean. Most sharks, like most fish, are ectothermic, meaning that their body temperatures match those of the surrounding water. But a handful of species, part of a group termed mackerel sharks, are endothermic: They have a specialized pattern of blood circulation that helps retain some of the heat their muscles produce. This enables them to keep some body parts at a higher temperature than their surroundings. A species called the salmon shark can maintain a body temperature that’s 20° C warmer than the sub-Arctic waters that it occupies.

Megalodon is also a mackerel shark, and some scientists have suggested that it, too, must have been at least partially endothermic to have maintained its growth rates in the varied environments that it inhabited. The 2023 study measured isotope clumping—which can provide an estimate of the temperature at which a material formed—in mastodon teeth. They confirmed that the megalodon samples were consistently warmer, with an average temperature difference of about 7° C compared to cold-blooded samples.

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with-fewer-pollinators,-plants-are-cutting-back-on-nectar-production

With fewer pollinators, plants are cutting back on nectar production

Biology, pansies, plant biology, pollen, pollinators, reproduction, Science / /

I can handle this myself —

Fewer pollinators means more self-pollination, less food for bees.

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Image of a field of multi-colored flowers.

In a striking experiment, scientists from the French Centre Nationale de la Recherche Scientifique (CNRS) and the University of Montpellier have observed the impact of selective pressure on a flowering plant. By comparing the pansy flower variety of today that grows in the Paris region to those regrown from the seeds of the same variety collected in the 1990s and 2000s, the researchers have observed notable differences.

According to the study’s co-author, Pierre-Oliver Cheptou, the plant’s evolution over this period has resulted in a 25 percent increase in self-pollination (or selfing) in modern two plants. “We also noticed a 10 percent decrease in the flower size and a 20 percent reduction in the nectar production, which suggests the decrease in rewards for pollinators such as bumblebees,” he said.

To confirm this outcome, Cheptou and his colleagues conducted behavioral tests involving bumblebees “which preferred the ancestor plants,” Cheptou said.

He added that the study showed the impact of pollinators’ decline on the reproductive system in these plants.

When mom and dad are the same plant

Elaborating on the experiment techniques, the study’s lead author, Samson Acoca-Pidolle, said the researchers used “resurrection ecology,” which involved using plant seeds from the 1990s and 2000s that were picked from the fields in the Paris region and stored in fridges in two botanical conservatories. “In 2021, we went to the same fields to collect the seeds of the descendants of the same flowering plant,” he said. For the study, all the plants were cultivated in a greenhouse at the same time of year to ensure consistency.

Cheptou said that to determine the selfing rates of the ancestor and descendant varieties, the team used a classical molecular technique that involved measuring the frequency at which individual plants had stretches of chromosomes with identical versions of genes. This happens often in selfing since the maternal and paternal copies of a chromosome come from the same individual.

According to Acoca-Pidolle, the research team was surprised at the rapidity of the plant’s evolution in the natural environment. “It seems that the pollinators’ decline is already strong, and there is already selective pressure on this species. The other significance of the result is that we are currently observing the breakdown in the plant-pollinator interaction for this species,” he added.

Acoca-Pidolle said the study suggests that the decline of pollinators could become self-reinforcing. “If plants produce less nectar, we can predict that pollinators will have less food and this could increase the pollinator decline,” he said.

Everything is a trade-off

This adaptation may not necessarily turn out to be beneficial for the plant. “It depends on the time scale we are considering this adaptation as an answer to the selective pressure. In the long term, we know that selfing species have a higher extinction rate than out-crossing species,” he said.

Although this study was restricted to a single plant species, Cheptou suspects a similar evolutionary adaptation could be taking place in other species, too. “For plants that can practice at least a little selfing, we should expect this result. But this has to be checked by experiments,” he said.

According to Cheptou, future research should investigate if a similar pattern exists in this plant species elsewhere in Europe and see if a similar adaptation has occurred in other species.

“The other interesting aspect would be to see if plants’ future evolution could be reversible, which will again make them more attractive to the pollinators and practice less selfing,” Acoca-Pidolle said.

New Phytologist, 2023. DOI: 10.1111/nph.19422

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big-evolutionary-change-tied-to-lots-of-small-differences

Big evolutionary change tied to lots of small differences

Biology, eggs, evolution, live birth, Science, snails / /

Cracking the eggs —

Lots of genes changed as a species of snail went from laying eggs to live births.

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Image of a dark, grey-black snail shell.

Enlarge / An example of a Littorina species, the common periwinkle.

The version of evolution proposed by Charles Darwin focused on slow, incremental changes that only gradually build into the sort of differences that separate species. But that doesn’t rule out the potential for sudden, dramatic changes. Indeed, some differences make it difficult to understand what a transitional state would look like, suggesting that a major leap might be needed.

A new study looks at one major transition: the shift from egg-laying to live births in a set of related snail species. By sequencing the genomes of multiple snails, the researchers identified the changes in DNA that are associated with egg-laying. It turns out that a large number of genes are associated with the change despite its dramatic nature.

Giving up eggs

The snails in question are in a genus called Littorina, which are largely distributed around the North Atlantic. Many of these species lay eggs, but a number of them have transitioned to live births. In these species, an organ that coats eggs with a protein-rich jelly in other species instead acts as an incubator, allowing eggs to develop until young snails can crawl out of their parent’s shells. This is thought to be an advantage for animals that would otherwise have to lay eggs in environments that aren’t favorable for their survival.

The egg laying species are so similar to their relatives that they were sometimes thought to just be a variant of an egg-laying species. All of which suggests that live birth has evolved relatively recently, giving us a good opportunity to understand the genetic changes that enabled it.

So, a large international team of researchers sequenced the genomes of over 100 individual snails, both egg-laying and live birth. The resulting data was used to analyze things like how closely related different species are, and what genetic changes are associated with live birth.

The results suggest that there are two separate clusters of species that reproduce through live births. Put differently, on an evolutionary tree of these snail species, there’s a branch full of egg-laying species separating two groups that give birth to live snails. Typically, this structure is viewed as an indication that live births evolved twice, once for each of the two clusters.

But that doesn’t seem to be the case here, for reasons that we’ll get into.

Lots of variations

Separately, the researchers looked for regions of the genome that are associated with giving live births. And they found lots of them—88 in total. These 88 regions were identified in both clusters of live-birth species, and the DNA sequences within them were very similar. This suggests that these regions had a single origin and were maintained in both these lineages.

One possibility to explain this is that a population of live-birth animals reverted to egg-laying at some point in their evolution. Alternatively, hybridization between egg-layers and live-birthers could have let these variations spread within an egg-laying population and ultimately re-enable live births when enough of them were present in individual animals, producing a separate live-birth lineage.

The 88 regions identified as underlying live births have very little genetic diversity, suggesting that a specific genetic variant in each region is so advantageous that it swept through the population, displacing all other versions of the stretch of DNA. They have, however, picked up some distinct variations that are rare outside the egg-laying populations—enough to allow the researchers to estimate the age when these pieces of DNA came under evolutionary selection.

The answer varies depending on which of the 88 segments you’re looking at, but it ranges from about 10,000 to 100,000 years ago. That range suggests that the genetic regions that enable live births were put together gradually over many years—exactly as the traditional view of evolution suggests.

The researchers acknowledge that at least some of these regions are likely to have evolved after live births were already the norm and simply improve the efficiency of the internal incubation. And there’s no way to know how many variants (or which) need to be present before live births are possible. However, the researchers now have an extensive list of genes to look into to understand things better.

Science, 2024. DOI: 10.1126/science.adi2982  (About DOIs).

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this-bird-is-like-a-gps-for-honey

This bird is like a GPS for honey

Behavioral science, Biology, birds, culture, honeyguide, language, Science / /

Show me the honey —

The honeyguide recognizes calls made by different human groups.

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A bird perched on a wall in front of an urban backdrop.

Enlarge / A greater honeyguide

With all the technological advances humans have made, it may seem like we’ve lost touch with nature—but not all of us have. People in some parts of Africa use a guide more effective than any GPS system when it comes to finding beeswax and honey. This is not a gizmo, but a bird.

The Greater Honeyguide (highly appropriate name), Indicator indicator (even more appropriate scientific name), knows where all the beehives are because it eats beeswax. The Hadza people of Tanzania and Yao people of Mozambique realized this long ago. Hadza and Yao honey hunters have formed a unique relationship with this bird species by making distinct calls, and the honeyguide reciprocates with its own calls, leading them to a hive.

Because the Hadza and Yao calls differ, zoologist Claire Spottiswoode of the University of Cambridge and anthropologist Brian Wood of UCLA wanted to find out if the birds respond generically to human calls, or are attuned to their local humans. They found that the birds are much more likely to respond to a local call, meaning that they have learned to recognize that call.

Come on, get that honey

To see which sound the birds were most likely to respond to, Spottiswoode and Wood played three recordings, starting with the local call. The Yao honeyguide call is what the researchers describe as “a loud trill followed by a grunt (‘brrrr-hm’) while the Hadza call is more of “a melodic whistle,” as they say in a study recently published in Science. The second recording they would play was the foreign call, which would be the Yao call in Hadza territory and vice versa.

The third recording was an unrelated human sound meant to test whether the human voice alone was enough for a honeyguide to follow. Because Hadza and Yao voices sound similar, the researchers would alternate among recordings of honey hunters speaking words such as their names.

So which sounds were the most effective cues for honeyguides to partner with humans? In Tanzania, local Hadza calls were three times more likely to initiate a partnership with a honeyguide than Yao calls or human voices. Local Yao calls were also the most successful in Mozambique, where, in comparison to Hadza calls and human voices, they were twice as likely to elicit a response that would lead to a cooperative effort to search for a beehive. Though honeyguides did sometimes respond to the other sounds, and were often willing to cooperate when hearing them, it became clear that the birds in each region had learned a local cultural tradition that had become just as much a part of their lives as those of the humans who began it.

Now you’re speaking my language

There is a reason that honey hunters in both the Hadza and Yao tribes told Wood and Spottiswoode that they have never changed their calls and will never change them. If they did, they’d be unlikely to gather nearly as much honey.

How did this interspecies communication evolve? Other African cultures besides the Hadza and Yao have their own calls to summon a honeyguide. Why do the types of calls differ? The researchers do not think these calls came about randomly.

Both the Hadza and Yao people have their own unique languages, and sounds from them may have been incorporated into their calls. But there is more to it than that. The Hadza often hunt animals when hunting for honey. Therefore, the Hadza don’t want their calls to be recognized as human, or else the prey they are after might sense a threat and flee. This may be why they use whistles to communicate with honeyguides—by sounding like birds, they can both attract the honeyguides and stalk prey without being detected.

In contrast, the Yao do not hunt mammals, relying mostly on agriculture and fishing for food. This, along with the fact that they try to avoid potentially dangerous creatures such as lions, rhinos, and elephants, and can explain why they use recognizably human vocalizations to call honeyguides. Human voices may scare these animals away, so Yao honey hunters can safely seek honey with their honeyguide partners. These findings show that cultural diversity has had a significant influence on calls to honeyguides.

While animals might not literally speak our language, the honeyguide is just one of many species that has its own way of communicating with us. They can even learn our cultural traditions.

“Cultural traditions of consistent behavior are widespread in non-human animals and could plausibly mediate other forms of interspecies cooperation,” the researchers said in the same study.

Honeyguides start guiding humans as soon as they begin to fly, and this knack, combined with learning to answer traditional calls and collaborate with honey hunters, works well for both human and bird. Maybe they are (in a way) speaking our language.

Science, 2023.  DOI: 10.1126/science.adh412

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otherworldly-mini-yellowstone-found-in-the-deep-sea

Otherworldly mini-Yellowstone found in the deep sea

Biology, Ecology, exploration, oceanography, Science / /

Follow the crabs —

We’ve known about deep ocean vents for a while, but it’s still hard to find them.

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A large collection of white crabs arrayed across rocks on the bottom of the ocean.

Enlarge / “Leading us like breadcrumbs…” A trail of squat lobsters helped researchers locate previously unknown hydrothermal vents. The hydrothermal vents create chemosynthetic ecosystems, so in areas that are mostly barren of life, the appearance of larger animals can be an indicator of vents nearby.

Spectacular scenery, from lush rainforests to towering mountain ranges, dots the surface of our planet. But some of Earth’s most iconic landmarks––ones that may harbor clues to the origin of life on Earth and possibly elsewhere––lay hidden at the bottom of the ocean. Scientists recently found one such treasure in Ecuadorian waters: a submerged mini Yellowstone called Sendero del Cangrejo.

This hazy alien realm simmers in the deep sea in an area called the Western Galápagos Spreading Center––an underwater mountain range where tectonic plates are slowly moving away from each other. Magma wells up from Earth’s mantle here to create new oceanic crust in a process that created the Galápagos Islands and smaller underwater features, like hydrothermal vents. These vents, which pump heated, mineral-rich water into the ocean in billowing plumes, may offer clues to the origin of life on Earth. Studying Earth’s hydrothermal vents could also offer a gateway to finding life, or at least its building blocks, on other worlds.

The newly discovered Sendero del Cangrejo contains a chain of hydrothermal vents that spans nearly two football fields. It hosts hot springs and geyser chimneys that support an array of creatures, from giant, spaghetti-like tube worms to alabaster Galatheid crabs.

The crabs, also known as squat lobsters, helped guide researchers to Sendero del Cangrejo. Ecuadorian observers chose the site’s name, which translates to “Trail of the Crabs,” in their honor.

“It did feel like the squat lobsters were leading us like breadcrumbs, like we were Hansel and Gretel, to the actual vent site,” said Hayley Drennon, a senior research assistant at Columbia University’s Lamont-Doherty Earth Observatory, who participated in the expedition.

The Iguanas Vent Field, where the team did some sampling.

Enlarge / The Iguanas Vent Field, where the team did some sampling.

The joint American and Ecuadorian research team set sail aboard the Schmidt Ocean Institute’s Falkor (too) research vessel in mid-August in search of new hydrothermal vents. They did some mapping and sampling on the way to their target location, about 300 miles off the west coast of the Galápagos.

The team used a ‘Tow-Yo’ technique to gather and transmit real-time data to the crew aboard the ship. “We lowered sensors attached to a long wire to the seafloor, and then towed the wire up and down like a yo-yo,” explained Roxanne Beinart, an associate professor at the University of Rhode Island and the expedition’s chief scientist. “This process allowed us to monitor changes in temperature, water clarity, and chemical composition to help pinpoint potential hydrothermal vent locations.”

When they reached a region that seemed promising, they deployed the remotely operated vehicle SuBastian for a better look. Less than 24 hours later, the team began seeing more and more Galatheid crabs, which they followed until they found the vents.

The crabs were particularly useful guides since the vent fluids there are clear, unlike “black smokers” that create easy-to-see plumes. SuBastian explored the area for about 43 hours straight in the robot’s longest dive to date.

But the true discovery process spanned decades. Researchers have known for nearly 20 years that the area was likely home to hydrothermal activity thanks to chemical signals measured in 2005. About a decade later, teams ventured out again and collected animal samples. Now, due to the Schmidt Ocean Institute’s recent expedition, scientists have the most comprehensive data set ever for this location. It includes chemical, geological, and biological data, along with the first high-temperature water samples.

“It’s not uncommon for an actual discovery like this to take decades,” said Jill McDermott, an associate professor at Lehigh University and the expedition’s co-chief scientist. “The ocean is a big place, and the locations are very remote, so it takes a lot of time and logistics to get out to them.” The team will continue their research onshore to help us understand how hydrothermal vents influence our planet.

Genesis from hell?

Sendero del Cangrejo may compare to a small-scale Yellowstone in some ways, but it’s no tourist destination. It’s pitch-black since sunlight can’t reach the deep ocean floor. The crushing weight of a mile of water presses down from overhead. And the vents are hot and toxic. Some of them clocked in at 290º C (550º F)—nearly hot enough to melt lead.

Before scientists discovered hydrothermal vents in 1977, they assumed such extreme conditions would preclude the possibility of life. Yet that trailblazing team saw multiple species thriving, including white clams that guided them to the vents the same way the Galatheid crabs led the modern researchers to Sendero del Cangrejo.

A series of seafloor photos shows the sudden appearance of live white clams that led scientists to find hydrothermal vents for the first time.

A series of seafloor photos shows the sudden appearance of live white clams that led scientists to find hydrothermal vents for the first time.

Before the 1977 find, no one knew life could survive in such a hostile place. Now, scientists know there are microbes called thermophiles that can only live in high temperatures (up to about 120º C, or 250º F).

Bacteria that surround hydrothermal vents don’t eat other organisms or create energy from sunlight like plants do. Instead, they produce energy using chemicals like methane or hydrogen sulfide that emanate from the vents. This process, called chemosynthesis, was first identified through the characterization of organisms discovered at these vents. Chemosynthetic bacteria are the backbone of hydrothermal vent ecosystems, serving as a nutrition source for higher organisms.

Some researchers suggest life on Earth may have originated near hydrothermal vents due to their unique chemical and energy-rich conditions. While the proposal remains unproven, the discovery of chemosynthesis opened our eyes to new places that could host life.

The possibility of chemosynthetic creatures diminishes the significance of so-called habitable zones around stars, which describe the orbital distances between which surface water can remain liquid on a planet or moon. The habitable zone in our own Solar System extends from about Venus’ orbit out nearly to Mars’.

NASA’s Europa Clipper mission is set to launch late next year to determine whether there are places below the surface of Jupiter’s icy moon, Europa, that could support life. It’s a lot colder out there, well beyond our Solar System’s habitable zone, but scientists think Europa is internally heated. It experiences strong tidal forces from Jupiter’s gravity, which could create hydrothermal activity on the moon’s ocean floor.

Several other moons in our Solar System also host subsurface oceans and experience the same tidal heating that could potentially create habitable conditions. By exploring Earth’s hydrothermal vents, scientists could learn more about what to look for in similar environments elsewhere in our Solar System.

“The Ocean’s Multivitamin”

While hydrothermal vents are relatively new to science, they’re certainly not new to our planet. “Vents have been active since Earth’s oceans first formed,” McDermott said. “They’ve been present in our oceans for as long as we’ve had them, so about 3 billion years.”

During that time, they’ve likely transformed our planet’s chemistry and geology by cycling chemicals and minerals from Earth’s crust throughout the ocean.

“All living things on Earth need minerals and elements that they get from the crust,” said Peter Girguis, a professor at Harvard University, who participated in the expedition. “It’s no exaggeration to say that all life on earth is inextricably tied to the rocks upon which we live and the geological processes occurring deep inside the planet…it’s like the ocean’s multivitamin.”

But the full extent of the impact hydrothermal vents have on the planet remains unknown. In the nearly 50 years since hydrothermal vents were first discovered, scientists have uncovered hundreds more spread around the globe. Yet no one knows how many remain unidentified; there are likely thousands more vents hidden in the deep. Detailed studies, like those the expedition scientists are continuing onshore, could help us understand how hydrothermal activity influences the ocean.

ROV SuBastian takes water and chemical samples from a black smoker hydrothermal vent in the Iguanas Vent Field, Galapagos Islands.

Enlarge / ROV SuBastian takes water and chemical samples from a black smoker hydrothermal vent in the Iguanas Vent Field, Galapagos Islands.

The team’s immediate observations offer a good starting point for their continued scientific sleuthing.

“I actually expected to find denser animal populations in some places,” Beinart said.

McDermott thinks that could be linked to the composition of the vent fluids. “Several of the vents were clear—not very particle-rich,” she said. “They’re probably lower in minerals, but we’re not sure why.” Now, the team will measure different metal levels in water samples from the vent fluids to figure out why they’re low in minerals and whether that has influenced the animals the vents host.

Researchers are learning more about hydrothermal vents every day, but many mysteries remain, such as the eventual influence ocean acidification could have on vents. As they seek answers, they’re sure to find more questions and open up new avenues of scientific exploration.

Ashley writes about space as a contractor for NASA’s Goddard Space Flight Center by day and freelances as an environmental writer. She holds a master’s degree in space studies from the University of North Dakota and is finishing a master’s in science writing through The Johns Hopkins University. She writes most of her articles with one of her toddlers on her lap.

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getting-to-the-bottom-of-how-red-flour-beetles-absorb-water-through-their-butts

Getting to the bottom of how red flour beetles absorb water through their butts

12 days of Christmas, agricultural sciences, animals, beetles, Biology, Biomechanics, genomes, Genomics, red flour beetle, Science / /

On the third day of Christmas —

A unique group of cells pumps water into the kidneys to help harvest moisture from the air.

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Who <em>doesn’t</em> thrill to the sight of a microscopic cross-section of a beetle’s rectum? You’re welcome.” src=”https://cdn.arstechnica.net/wp-content/uploads/2023/03/beetle-butt-TOP-800×536.jpg”></img><figcaption> <p><a data-height=Enlarge / Who doesn’t thrill to the sight of a microscopic cross-section of a beetle’s rectum? You’re welcome.

Kenneth Veland Halberg

There’s rarely time to write about every cool science-y story that comes our way. So this year, we’re once again running a special Twelve Days of Christmas series of posts, highlighting one science story that fell through the cracks in 2023, each day from December 25 through January 5. Today: red flour beetles can use their butts to suck water from the air, helping them survive in extremely dry environments. Scientists are honing in on the molecular mechanisms behind this unique ability.

The humble red flour beetle (Tribolium castaneum) is a common pantry pest feeding on stored grains, flour, cereals, pasta, biscuits, beans, and nuts. It’s a remarkably hardy creature, capable of surviving in harsh arid environments due to its unique ability to extract fluid not just from grains and other food sources, but also from the air. It does this by opening its rectum when the humidity of the atmosphere is relatively high, absorbing moisture through that opening and converting it into fluid that is then used to hydrate the rest of the body.

Scientists have known about this ability for more than a century, but biologists are finally starting to get to the bottom (ahem) of the underlying molecular mechanisms, according to a March paper published in the Proceedings of the National Academies of Science. This will inform future research on how to interrupt this hydration process to better keep red flour beetle populations in check, since they are highly resistant to pesticides. They can also withstand even higher levels of radiation than the cockroach.

There are about 400,000 known species of beetle roaming the planet although scientists believe there could be well over a million. Each year, as much as 20 percent of the world’s grain stores are contaminated by red flour beetles, grain weevils, Colorado potato beetles, and confused flour beetles, particularly in developing countries. Red flour beetles in particular are a popular model organism for scientific research on development and functional genomics. The entire genome was sequenced in 2008, and the beetle shares between 10,000 and 15,000 genes with the fruit fly (Drosophila), another workhorse of genetics research. But the beetle’s development cycle more closely resembles that of other insects by comparison.

Food security in developing nations is particularly affected by animal species like the red flour beetle which has specialized in surviving in extremely dry environments, granaries included, for thousands of years.

Enlarge / Food security in developing nations is particularly affected by animal species like the red flour beetle which has specialized in surviving in extremely dry environments, granaries included, for thousands of years.

Kenneth Halberg

The rectums of most mammals and insects absorb any remaining nutrients and water from the body’s waste products prior to defecation. But the red flour beetle’s rectum is a model of ultra-efficiency in that regard. The beetle can generate extremely high salt concentrations in its kidneys, enabling it to extract all the water from its own feces and recycle that moisture back into its body.

“A beetle can go through an entire life cycle without drinking liquid water,” said co-author Kenneth Veland Halberg, a biologist at the University of Copenhagen. “This is because of their modified rectum and closely applied kidneys, which together make a multi-organ system that is highly specialized in extracting water from the food that they eat and from the air around them. In fact, it happens so effectively that the stool samples we have examined were completely dry and without any trace of water.” The entire rectal structure is encased in a perinephric membrane.

Halberg et al. took took scanning electron microscopy images of the beetle’s rectal structure. They also took tissue samples and extracted RNA from lab-grown red flour beetles, then used a new resource called BeetleAtlas for their gene expression analysis, hunting for any relevant genes.

One particular gene was expressed sixty times more in the rectum than any other. Halberg and his team eventually honed in a group of secondary cells between the beetle’s kidneys and circulatory system called leptophragmata. This finding supports prior studies that suggested these cells might be relevant since they are the only cells that interrupt the perinephric membrane, thereby enabling critical transport of potassium chloride. Translation: the cells pump salts into the kidneys to better harvest moisture from its feces or from the air.

Model of the beetle's inside and how it extracts water from the air.

Enlarge / Model of the beetle’s inside and how it extracts water from the air.

Kenneth Halberg

The next step is to build on these new insights to figure out how to interrupt the beetle’s unique hydration process at the molecular level, perhaps by designing molecules that can do so. Those molecules could then be incorporated into more eco-friendly pesticides that target the red flour beetle and similar pests while not harming more beneficial insects like bees.

“Now we understand exactly which genes, cells and molecules are at play in the beetle when it absorbs water in its rectum. This means that we suddenly have a grip on how to disrupt these very efficient processes by, for example, developing insecticides that target this function and in doing so, kill the beetle,” said Halberg. “There is twenty times as much insect biomass on Earth than that of humans. They play key roles in most food webs and have a huge impact on virtually all ecosystems and on human health. So, we need to understand them better.”

DOI: PNAS, 2023. 10.1073/pnas.2217084120  (About DOIs).

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corvids-seem-to-handle-temporary-memories-the-way-we-do

Corvids seem to handle temporary memories the way we do

animal behavior, Biology, neurobiology, Science, working memory / /

Working on memory —

Birds show evidence that they lump temporary memories into categories.

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A black bird with yellow eyes against a blue sky.

Enlarge / A jackdaw tries to remember what color it was thinking of.

Humans tend to think that we are the most intelligent life-forms on Earth, and that we’re largely followed by our close relatives such as chimps and gorillas. But there are some areas of cognition in which homo sapiens and other primates are not unmatched. What other animal’s brain could possibly operate at a human’s level, at least when it comes to one function? Birds—again.

This is far from the first time that bird species such as corvids and parrots have shown that they can think like us in certain ways. Jackdaws are clever corvids that belong to the same family as crows and ravens. After putting a pair of them to the test, an international team of researchers saw that the birds’ working memory operates the same way as that of humans and higher primates. All of these species use what’s termed “attractor dynamics,” where they organize information into specific categories.

Unfortunately for them, that means they also make the same mistakes we do. “Jackdaws (Corvus monedula) have similar behavioral biases as humans; memories are less precise and more biased as memory demands increase,” the researchers said in a study recently published in Communications Biology.

Remembering not to forget

Working memory is where we hang on to items for a brief period of time—like a postal code looked up in one browser tab and typed into a second. It can hold everything from numbers and words to images and concepts. But these memories deteriorate quickly, and the capacity is limited—the more things we try to remember, the less likely the brain is going to remember them all correctly.

Attractor dynamics give the brain an assist with working memory by taking sensory input, such as color, and categorizing it. The highly specific red shade “Fire Lily” might fade from working memory quickly, and fewer specifics will stick around as time passes, yet it will still be remembered as “red.” You lose specifics first, but hang on to the general idea longer.

Aside from time, the other thing that kills working memory is distractions. Less noise—meaning distracting factors inside and outside the brain—will make it easier to distinguish Fire Lily among the other reds. If a hypothetical customer was browsing paint swatches for Sandstone (a taupe) and London Fog (a gray) in addition to Fire Lily, remembering each color accurately would become even more difficult because of the increased demands on working memory.

Bias can also blur working memory and cause the brain to remember some red hues more accurately than others, especially if the brain compartmentalizes them all under “red.” This can happen when a particular customer has a certain idea of the color red that leans warmer or cooler than Fire Lily. If they view red as leaning slightly warmer than Fire Lily, they might believe a different, warmer red is Fire Lily.

In living color

To find out if corvids process stimuli using short-term memory with attractor dynamics, the researchers subjected two jackdaws to a variety of tests that involved remembering colors. Each bird had to peck on a white button to begin the test. They were then shown a color—the target color—before being shown a chart of 64 colors. The jackdaws had to look at that chart and peck the color they had previously been shown. A correct answer would get them their favorite treat, while responses that were close but not completely accurate would get them other treats.

While the birds performed well with just one color, their accuracy went down as the researchers challenged them to remember more target colors from the chart at once. They were more likely to pick colors that were close to, but not exactly, the target colors they had been shown—likely because there was a greater load on their short-term memory.

This is what we’d see if a customer had to remember not only Fire Lily, but Sandstone and London Fog. The only difference is that we humans would be able to read the color names, and the jackdaws only found out they were wrong when they didn’t get their favorite treat.

“Despite vastly different visual systems and brain organizations, corvids and primates show similar attractor dynamics, which can mitigate noise in visual working memory representations,” the researchers said in the same study.

How and why birds evolved attractor dynamics still needs to be understood. Because avian eyesight differs from human eyesight, there could have been differences in color perception that the research team was unable to account for. However, it seems that the same mechanisms for working memory that evolved in humans and other primates also evolved separately in corvids. “Birdbrain” should be taken as a compliment.

Communications Biology, 2023. DOI:  10.1038/s42003-023-05442-5

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study:-“smarter”-dogs-think-more-like-humans-to-overcome-their-biases

Study: “Smarter” dogs think more like humans to overcome their biases

animal behavior, animal cognition, animals, Biology, Dogs, Science, spatial bias / /

who’s a smart doggo? —

Both the shape of a dog’s head and cognitive ability determine degree of spatial bias.

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dog in a harness approaching a blue dish on the floor

Enlarge / Look at this very good boy taking a test to determine the origin of his spatial bias for a study on how dogs think.

Eniko Kubinyi

Research has shown that if you point at an object, a dog will interpret the gesture as a directional cue, unlike a human toddler, who will more likely focus on the object itself. It’s called spatial bias, and a recent paper published in the journal Ethology offers potential explanations for why dogs interpret the gesture the way that they do. According to researchers at Eötvös Loránd University in Hungary, the phenomenon arises from a combination of how dogs see (visual acuity) and how they think, with “smarter” dog breeds prioritizing an object’s appearance as much as its location. This suggests the smarter dogs’ information processing is more similar to humans.

The authors wanted to investigate whether spatial bias in dogs is sensory or cognitive, or a combination of the two. “Very early on, children interpret the gesture as pointing to the object, while dogs take the pointing as a directional cue,” said co-author Ivaylo Iotchev. “In other words, regardless of the intention of the person giving the cue, the meaning for children and dogs is different. This phenomenon has previously been observed in dogs using a variety of behavioral tests, ranging from simple associative learning to imitation, but it had never been studied per se.”

Their experimental sample consisted of dogs used in a previous 2018 study plus dogs participating specifically in the new study, for a total of 82 dogs. The dominant breeds were border collies (19), vizslas (17), and whippets (6). Each animal was brought into a small empty room with their owner and one of the experimenters present. The experimenter stood 3 meters away from the dog and owner. There was a training period using different plastic plates to teach the dogs to associate either the presence or absence of an object, or its spatial location, with the presence or absence of food. Then they tested the dogs on a series of tasks.

An object feature conditioning test involving a white round plate and a black square plate.

Enlarge / An object feature conditioning test involving a white round plate and a black square plate.

I.B. Iotchev et al., 2023

For instance, one task required dogs to participate in a maximum of 50 trials to teach them to learn a location of a treat that was always either on the left or right plate. For another task, the experimenter placed a white round plate and a black square plate in the middle of the room. The dogs were exposed to each semi-randomly but only received food in one type of plate. Learning was determined by how quickly each dog ran to the correct plate.

Once the dogs learned those first two tasks, they were given another more complicated task in which either the direction or the object was reversed: if the treat had previously been placed on the right, now it would be found on the left, and if it had previously been placed on a white round plate, it would now be found on the black square one. The researchers found that dogs learned faster when they had to choose the direction, i.e., whether the treat was located on the left or the right. It was harder for the dogs to learn whether a treat would be found on a black square plate or a white round plate.

The shorter a dog's head, the higher the

Enlarge / The shorter a dog’s head, the higher the “cephalic index” (CI).

I.B. Iotchev et al., 2023

Next the team needed to determine differences between the visual and cognitive abilities of the dogs in order to learn whether the spatial bias was sensory or cognitively based, or both. Selective breeding of dogs has produced breeds with different visual capacities, so another aspect of the study involved measuring the length of a dog’s head, which prior research has shown is correlated with visual acuity. The metric used to measure canine heads is known as the “cephalic index” (CI), defined as the ratio of the head’s maximum width multiplied by 100, then divided by the head’s maximum length.

The shorter a dog’s head, the more similar their visual acuity is to human vision. That’s because there is a higher concentration of retinal ganglion cells in the center of their field of vision, making vision sharper and giving such dogs binocular depth vision. The testing showed dogs with better visual acuity, and who also scored higher on the series of cognitive tests, also exhibited less spatial bias. This suggests that canine spatial bias is not simply a sensory matter but is also influenced by how they think. “Smarter” dogs have less spatial bias.

As always, there are a few caveats. Most notably, the authors acknowledge that their sample consisted exclusively of dogs from Hungary kept as pets, and thus their results might not generalize to stray dogs, for example, or dogs from other geographical regions and cultures. Still, “we tested their memory, attention skills, and perseverance,” said co-author Eniko Kubinyi. “We found that dogs with better cognitive performance in the more difficult spatial bias task linked information to objects as easily as to places. We also see that as children develop, spatial bias decreases with increasing intelligence.”

DOI: Ethology, 2023. 10.1111/eth.13423  (About DOIs).

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contact-tracing-software-could-accurately-gauge-covid-19-risk

Contact-tracing software could accurately gauge COVID-19 risk

Biology, COVID-19, epidemiology, infectious diseases, SARS-CoV-2, Science / /

As it turns out, epidemiology works —

Time spent with infected individuals is a key determinant of risk.

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A woman wearing a face mask and checking her phone.

It’s summer 2021. You rent a house in the countryside with a bunch of friends for someone’s birthday. The weather’s gorgeous that weekend, so mostly you’re all outside—pool, firepit, hammock, etc.—but you do all sleep in the same house. And then on Tuesday, you get an alert on your phone that you’ve been exposed to SARS-CoV-2, the virus that causes COVID-19. How likely are you to now have it?

To answer that question, a group of statisticians, data scientists, computer scientists, and epidemiologists in the UK analyzed 7 million people who were notified that they were exposed to COVID-19 by the NHS COVID-19 app in England and Wales between April 2021 and February 2022. They wanted to know if—and how—these app notifications correlated to actual disease transmission. Analyses like this can help ensure that an app designed for the next pathogen could retain efficacy while minimizing social and economic burdens. And it can tell us more about the dynamics of SARS-CoV-2 transmission.

Over 20 million quarantine requests

The NHS COVID-19 app was active on 13 to 18 million smartphones per day in 2021. It used Bluetooth signals to estimate the proximity between those smartphones while maintaining privacy and then alerted people who spent 15 minutes or more at a distance of 2 meters or less from a confirmed case. This led to over 20 million such alerts, each of which came with a request to quarantine—quite a burden.

The researchers found that the app did, in fact, accurately translate the duration and proximity of a COVID-19 exposure to a relevant epidemiological risk score. The app assessed a contact’s risk by multiplying the length of contact, the proximity of contact, and the infectiousness of the index case as determined by how long it had been since the index case started showing symptoms or tested positive.

There was an increasing probability of reported infection as the app’s risk score increased: more contacts whom the app deemed were at a high transmission risk did go on to test positive for COVID-19 within the following two weeks than those who were notified but had lower risk levels. (That’s positive tests that were reported by using the app. Some of the high-risk people probably did not test at all, did not report their test results, or did not report them within the allotted time. So this is an underestimation of the correlation between notification of risk and infection.)

More exposure = higher risk

When the researchers separated the factors contributing to the risk of an exposure, they found that duration was the most important indicator. Household exposures accounted for 6 percent of all contacts but 41 percent of transmissions.

One caveat: The app didn’t record any contextual variables that are known to impact transmission risk, like if people live in an urban or rural area, was the meeting indoors or outdoors, was it during the week or over the weekend, was anyone vaccinated, etc. Including such data could make risk assessment more accurate.

Based on their work, the researchers suggest that an “Amber Alert” stage could have been introduced to the app, in which people deemed to have an interim degree of risk would be guided to get a PCR test rather than immediately jumping to quarantine. Including this intermediate Amber Alert population could have significantly reduced the socioeconomic costs of contact tracing while retaining its epidemiological impact or could have increased its effectiveness for a similar cost. Performing analyses like this early on in the next pandemic to determine how it is transmitted might minimize illness and strain on society.

Nature, 2023.  DOI:  10.1038/s41586-023-06952-2

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human-brain-cells-put-much-more-energy-into-signaling

Human brain cells put much more energy into signaling

Biology, brain, frontal cortex, nerve cells, neurobiology, Science, signaling / /

Being human is hard —

Signaling molecules help modulate the brain’s overall activity.

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Image of a person staring pensively, with question marks drawn on the wall behind him.

Indian elephants have larger brains than we do (obviously). Mice have a higher brain-to-body mass ratio, and long-finned pilot whales have more neurons. So what makes humans—and more specifically, human brains—special?

As far as organs go, human brains certainly consume a ton of energy—almost 50 grams of sugar, or 12 lumps, every day. This is one of the highest energy demands relative to body metabolism known among species. But what uses up all of this energy? If the human brain is the predicted size and has the predicted number of neurons for a primate of its size, and each individual neuron uses comparable amounts of energy to those in other mammals, then its energy use shouldn’t be exceptional.

The cost of signaling

A group of neuroscientists speculated that maybe the amount of signaling that takes place within the human brain accounts for its heightened energy needs. A consequence of this would be that brain regions that are more highly connected and do more signaling will use more energy.

To test their hypothesis, the scientists started by imaging the brains of 30 healthy, right-handed volunteers between 20 and 50 years old. The imaging took place at two separate institutions, and it allowed the researchers to correlate a given brain region’s energy use (as measured by glucose metabolism) with its level of signaling and connectivity. They found that energy use and signaling scaled in tandem in all 30 brains. But certain regions stuck out. Signaling pathways in certain areas of the cortex—the front of the brain—require almost 70 percent more energy than those in sensory-motor regions.

The frontal cortex is one of the regions that expanded the most during human evolution. According to Robert Sapolsky, “What the prefrontal cortex is most about is making tough decisions in the face of temptation—gratification postponement, long-term planning, impulse control, emotional regulation. The PFC is essential for getting you to do the right thing when it is the harder thing to do.” This is the stuff that humans must constantly contend with. And energetically, it is extraordinarily costly.

Increased modulation is also key for cognition

It is not only signaling that takes energy; it is modulating that signaling, ensuring that it occurs at the appropriate levels and only at the appropriate times.

Using the Allen Human Brain Atlas, these researchers looked at gene activity in the frontal cortex. They found elevated activity of neuromodulators and their receptors. The authors note that “the human brain spends excessive energy on the long-lasting regulation of (fast) neurotransmission with (slow) neuromodulators such as serotonin, dopamine, or noradrenaline.” And also endogenous opiates. “This effect is more about setting the tone of general excitability than transferring individual bits of information,” they write.

Once they correlated energy use to signaling and slow-acting neuromodulation in the cortex, the last thing the scientists did was look at the Neurosynth project, which maps cognitive functions to brain regions. Lo and behold, the energy-hogging, highly connected, strongly modulated, and evolutionarily expanded parts of the cortex are the same ones involved in complex functions like memory processing, reading, and cognitive inhibition. This supports their idea of “an expensive signaling architecture being dedicated to human cognition.”

Science Advances, 2023.  DOI: 10.1126/sciadv.adi7632

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What happens in a crow’s brain when it uses tools? 

Behavioral science, Biology, birds, Crows, neurobiology, Science, tool use / /

This is your brain on tools —

Researchers trace the areas of the brain that are active when birds are using tools.

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Three crows on the streets in the foreground with traffic and city lights blurry in the background.

Enlarge / Sure, they can use tools, but do they know where the nearest subway stop is?

“A thirsty crow wanted water from a pitcher, so he filled it with pebbles to raise the water level to drink,” summarizes a famous Aesop Fable. While this tale is thousands of years old, animal behaviorists still use this challenge to study corvids (which include crows, ravens, jays, and magpies) and their use of tools. In a recent Nature Communications study, researchers from a collaboration of universities across Washington, Florida, and Utah used radioactive tracers within the brains of several American crows to see which parts of their brains were active when they used stones to obtain food from the bottom of a water-filled tube.

Their results indicate that the motor learning and tactile control centers were activated in the brains of the more proficient crows, while the sensory and higher-order processing centers lit up in the brains of less proficient crows. These results suggest that competence with tools is linked to certain memories and muscle control, which the researchers claimed is similar to a ski jumper visualizing the course before jumping.

The researchers also found that out of their avian test subjects, female crows were especially proficient at tool usage, succeeding in the challenge quickly. “[A] follow-up question is whether female crows actually have more need for creative thinking relative to male crows,” elaborates Loma Pendergraft, the study’s first author and a graduate student at the University of Washington, who wants to understand if the caregiving and less dominant role of female crows gives them a higher capacity for tool use.

While only two species of crow (the New Caledonian crow and the Hawaiian crow) inherently use twigs and sticks as foraging tools, this study also suggests that other crow species, like the American crow, have the neural flexibility to learn to use tools.

A less invasive look at bird brains

Due to their unique behaviors, complex social structures, and reported intelligence, crows have fascinated animal behavioralists for decades. Scientists can study crows’ brains in real time by using 18F-fluorodeoxyglucose (FDG), a radioactive tracer, which the researchers injected into the crows’ brains. They then use positron emission tomography (PET) scans to see which brain areas are activated during different tasks.

“FDG-PET is a method we use to remotely examine activity throughout the entire brain without needing to do any surgeries or implants,” explained Pendergraft. “It’s like [a functional] MRI.” The FDG-PET method is non-invasive, as the crows aren’t required to sit still, which minimizes the stress the crows feel during the experiment.  In the Nature Communications study, Pendergraft and his team ensured the crows were anesthetized before scanning them.

FDG is also used in various medical imaging techniques, such as diagnosing Alzheimer’s disease or screening for cancerous tissue. “Basically, the body treats it as glucose, a substance needed for cells to stay alive,” Pendergraft added. “If a body part is working harder than normal, it’s going to need extra glucose to power the additional activity. This means we can measure relative FDG concentrations within the brain as a proxy for relative brain activity.”

What happens in a crow’s brain when it uses tools?  Read More »