Oldest army ant ever discovered reveals iconic predator once raided Europe

Their nomadic lifestyle and ravenous raiding have taken army ants (Dorylinae) to most continents on Earth, but a rare fossil discovery is now offering first evidence that the infamous predators once swarmed a land they are strikingly absent from today -- Europe.

In the journal Biology Letters, researchers at New Jersey Institute of Technology and Colorado State University have reported the discovery of the oldest army ant on record, preserved in Baltic amber dating to the Eocene (~35 million years ago).

The eyeless specimen Dissimulodorylus perseus (D. perseus) -- named after the mythical Greek hero Perseus who famously defeated Medusa with the limited use of sight -- marks just the second fossil army ant species ever described, and the first army ant fossil recovered from the Eastern Hemisphere.

Sized at roughly 3 millimeters in length, researchers say the ant fossil brings to light previously unknown army ant lineages that would have existed across Continental Europe before undergoing extinction in the past 50 million years.

Remarkably, the fossil had been kept in obscurity for nearly 100 years in the Museum of Comparative Zoology at Harvard University, before being identified by the paper's lead author and NJIT Ph.D. candidate, Christine Sosiak.

"The museum houses hundreds of drawers full of insect fossils, but I happened to come across a tiny specimen labeled as a common type of ant while gathering data for another project," said Sosiak. "Once I put the ant under the microscope, I immediately realized the label was inaccurate … I thought, this is something really different."

"This amber would have been excavated around or before the 1930s, so to now learn it contained a rare army ant is surprising enough, much less one that demonstrates these ants roamed Europe," said Phillip Barden, assistant professor of biology at NJIT and senior author of the paper. "From everything we know about army ants living today, there's no hint of such extinct diversity. … With this fossil now out of obscurity, we've gained a rare paleontological porthole into the history of these unique predators."

A Paleontological Porthole into a Unique Predator's History

Today, there are about 270 army ant species living in the Eastern Hemisphere, and roughly 150 across North and South America.

Based on X-ray and CT-scan analysis of the fossil, the NJIT team gathered phylogenetic and morphological data that places D. perseus as a close relative to eyeless species of army ants currently found in Africa and Southern Asia, called Dorylus.

"At the time the fossil formed, Europe was hotter and wetter than it is today and may have provided an ideal habitat for ancient army ants," said Barden. "Europe underwent several cooling cycles over tens of millions of years since the Eocene, however, which may have been inhospitable to these tropical-adapted species."

The team's analysis further revealed that the ant possessed an enlarged antibiotic gland, typically found in other army ants for sustaining life underground, suggesting the long-lost European army ant lineage was similarly suited to subterranean living.

It's a factor Sosiak says makes this fossil, and other fossil army ants, a rarity. Only one definitive fossil had been recorded until now, unearthed from the Caribbean (16 ~Ma.).

"This was an incredibly lucky find. Because this ant was probably subterranean like most army ants today, it was much less likely to come into contact with tree resin that forms such fossils," said Sosiak. "We have a very small window into the history of life on our planet, and unusual fossils such as this provide fresh insight."

Sosiak says D. perseus' anatomical traits -- including its sharply pointed mandibles and lack of eyes -- help classify the specimen as a worker ant in its colony, which would have been involved in carrying its queen's larvae and raiding for food with soldier ants when it was alive.

"Army ant workers participate in raiding swarms, hunting other insects and even vertebrates. Because these army ants are blind, they use chemical communication to stay coordinated with one another to take down large prey," explained Sosiak. "This worker may have strayed too far from its fellow hunters and into sticky tree resin, which eventually solidified and encased the ant as we see it today."

Army ants' distinct combination of behavior and traits is so unusual in the ant world, that it's warranted its own name -- army ant syndrome.

In contrast with other ant lineages, army ants have wingless queens capable of laying millions of eggs a day, while their nomadic colonies temporarily occupy nests between phases of travel that take the shape of bivouacs, sometimes involving millions of ants stretching for 100m.

The carnivores are perhaps best known for their highly coordinated foraging that can involve consuming upwards of 500,000 prey a day.

Barden says army ant syndrome is a case of convergent evolution that would have occurred twice -- once in the Neotropics and once in the Afrotropics.

"The discovery is the first physical evidence of the army ant syndrome in the Eocene, establishing that hallmarks of these specialized predators were in place even before the ancestors of certain army ants like Dorylus," said Barden.

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Psychology: What gazes reveal about us

A new study by the TU Dresden shows that eye movements during the processing of tasks provide information about what the respective person is currently occupied with and what goals are being pursued within the task. These findings could play a role in the organization of screen work in the future.

We constantly move our eyes to obtain important information from the environment. Measuring eye movements allows to understand how information is processed. Previous work has shown that new visual information leads to a certain pattern of eye movements In particular, two types of visual processing are distinguished. In the so-called ambient mode, the eyes move rapidly over large distances to initially gain rough impressions of potentially interesting targets. It is therefore used for general spatial orientation. Once this process is complete, specific information is viewed for longer periods of time and processed more deeply, depending on the target and the level of interest. This is the so-called focus mode. So far, these changes in gaze patterns have mainly been found in the context of changes in the environment, that is external stimuli.

In a recent study by the Chair of Engineering Psychology at Technische Universität Dresden, Sebastian Pannasch and his team have now investigated the extent to which such patterns also occur as a result of internal stimuli. For this purpose, the test subjects were asked to solve a task on a computer screen in which they had to assemble a Rubik's cube according to a model so that all sides corresponded exactly to the model specifications. The external stimulus, i.e., the setting on the screen and the task, remained the same. Evaluation of the measured eye movements showed that the environmental mode for reorientation always occurred when information was taken in during different subtasks of the puzzle, e.g., when a puzzle piece was selected or checked to see if it matched the specification.

For Sebastian Pannasch, professor of engineering psychology and applied cognitive research at Technische Universität Dresden, the new findings are promising: "Our results show that the eyes are not only a proverbial mirror of the soul, but actually and measurably provide information about what we are currently engaged in and what goals we are pursuing within a task. Eye movements could be an indicator of the state of attention during task processing. In further studies, we will therefore investigate whether these new findings can be used to organize screen work."

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Pair of studies uncover surprising new roles for spinal cord and brainstem in touch

The sense of touch is essential to almost everything we do, from routine tasks at home to navigating unfamiliar terrains that may conceal dangers. Scientists have long been interested in understanding exactly how the touch information we obtain with our hands and other parts of the body makes its way to the brain to create the sensations we feel.

Yet, key aspects of touch -- including how the spinal cord and brainstem are involved in receiving, processing, and transmitting signals -- have remained poorly understood.

Now, a pair of papers by scientists at Harvard Medical School reveal critical new insights into how the spinal cord and brainstem contribute to the sense of touch.

Specifically, the research shows that the spinal cord and the brainstem, previously thought to be mere relay centers for touch information, are actively involved in processing touch signals as they travel to higher-order brain regions.

One study, published Nov. 4 in Cell, shows that specialized neurons in the spinal cord form a complex network that processes light touch -- think the brush of a hand or a peck on the cheek -- and sends this information to the brainstem.

In another study, published Nov. 23 in Nature, researchers established that direct and indirect touch pathways work together, converging in the brainstem to shape how touch is processed.

"These studies focus the spotlight on the spinal cord and the brainstem as sites where touch information is integrated and processed to convey different types of touch. We hadn't fully appreciated before how these areas contribute to the brain's representation of vibration, pressure, and other features of tactile stimuli," said David Ginty, the Edward R. and Anne G. Lefler Professor of Neurobiology in the Blavatnik Institute at HMS and the senior author on both papers.

Although the studies were conducted in mice, mechanisms for touch are largely conserved across species, including humans, which means the basics of touch processing could be useful for scientists studying human conditions such as neuropathic pain characterized by touch dysfunction.

"This detailed understanding of tactile sensation -- that is, feeling the world through contact with the skin -- may have profound implications for understanding how disease, disorder, and injury can affect our ability to interact with the environment around us," said James Gnadt, program director at the National Institute of Neurological Disorders and Stroke (NINDS), which provided part of the funding for the studies.

Overlooked and underappreciated

The historical view of touch is that sensory neurons in the skin encounter a touch stimulus such as pressure or vibration and send this information in the form of electrical impulses that travel directly from the skin to the brainstem. There, other neurons relay touch information to the brain's primary somatosensory cortex -- the highest level of the touch hierarchy -- where it is processed into sensation.

However, Ginty and his team wondered if and how the spinal cord and brainstem are involved in processing touch information. These areas occupy the lowest level of the touch hierarchy, and combine to form a more indirect touch pathway into the brain.

"People in the field thought that the diversity and richness of touch came just from sensory neurons in the skin, but that thinking bypasses the spinal cord and brainstem," said Josef Turecek, a postdoctoral fellow in the Ginty lab and the first author on the Nature paper.

Many neuroscientists are not familiar with spinal cord neurons, called postsynaptic dorsal column (PSDC) neurons, that project from the spinal cord into the brainstem -- and textbooks tend to leave PSDC neurons out of diagrams depicting the details of touch, Turecek explained.

For Ginty, the way that the spinal cord and brainstem have been overlooked in touch brings to mind early research on the visual system. Initially, scientists studying vision thought that all processing occurred in the visual cortex of the brain. However, it turned out that the retina, which receives visual information long before it reaches the cortex, is heavily involved in processing this information.

"Analogous to research on the visual system, these two papers address how touch information coming from the skin is processed in the spinal cord and brainstem before it moves up the touch hierarchy to more complex brain regions," Ginty said.

Connecting the dots

In the Cell paper, the researchers used a technique they developed to simultaneously record the activity of many different neurons in the spinal cord as mice experienced various types of touch. They discovered that over 90 percent of neurons in the dorsal horn -- the sensory processing area of the spinal cord -- responded to light touch.

"This was surprising because classically it was thought that dorsal horn neurons in the superficial layers of the spinal cord respond mostly to temperature and painful stimuli. We hadn't appreciated how light-touch information is distributed in the spinal cord," said Anda Chirila, a research fellow in the Ginty lab and the co-lead author on the paper with graduate student Genelle Rankin.

Moreover, these responses to light touch varied considerably across genetically different populations of neurons in the dorsal horn, which were found to form a highly interconnected and complex neural network. This variation in responses, in turn, gave rise to a diversity of touch information carried from the dorsal horn to the brainstem by PSDC neurons. In fact, when the researchers silenced various dorsal horn neurons, they saw a reduction in the diversity of light-touch information conveyed by PSDC neurons.

"We think this information on how touch is encoded in the spinal cord, which is the first site in the touch hierarchy, is important for understanding fundamental aspects of touch processing," Chirila said.

In their other study, published in Nature, scientists focused on the next step in the touch hierarchy: the brainstem. They explored the relationship between the direct pathway from sensory neurons in the skin to the brainstem and the indirect pathway that sends touch information through the spinal cord, as described in the Cell paper.

"Brainstem neurons get both direct and indirect input, and we were really curious about what aspects of touch each pathway brings to the brainstem," Turecek said.

To parse this question, the researchers alternately silenced each pathway and recorded the response of neurons in mouse brainstems. The experiments showed that the direct pathway is important for communicating high-frequency vibration, while the indirect pathway is needed to encode the intensity of pressure on the skin.

"The idea is that these two pathways converge in the brainstem with neurons that can encode both vibration and intensity, so you can shape responses of those neurons based on how much direct and indirect input you have," Turecek explained. In other words, if brainstem neurons have more direct than indirect input, they communicate more vibration than intensity, and vice versa.

Additionally, the team discovered that both pathways can convey touch information from the same small area of skin, with information on intensity detouring through the spinal cord before joining information on vibration that travels directly to the brainstem. In this way, the direct and indirect pathways work together, enabling the brainstem to form a spatial representation of different types of touch stimuli from the same area.

Finally on the map

Up until now, "most people have viewed the brainstem as a relay station for touch, and they haven't even had the spinal cord on the map at all," Ginty said. For him, the new studies "demonstrate that there's a tremendous amount of information processing occurring in the spinal cord and brainstem -- and this processing is critical for how the brain represents the tactile world."

Such processing, he added, likely contributes to the complexity and diversity of the touch information that the brainstem sends to the somatosensory cortex.

Next, Ginty and team plan to repeat the experiments in mice that are awake and behaving, to test the findings under more natural conditions. They also want to expand the experiments to include more types of real-world touch stimuli, such as texture and movement.

The researchers are also interested in how information from the brain -- for example, about an animal's level of stress, hunger, or exhaustion -- affects how touch information is processed in the spinal cord and brainstem. Given that touch mechanisms appear to be conserved across species, such information may be especially relevant for human conditions such as autism spectrum disorders or neuropathic pain, in which neural dysfunction causes hypersensitivity to light touch.

"With these studies we've laid the fundamental building blocks for how these circuits work and what their importance is," Rankin said. "Now we have the tools to dissect these circuits to understand how they're functioning normally, and what's changing when something goes wrong."

Read more at Science Daily

Less intensively managed grasslands have higher plant diversity and better soil health

Researchers have shown -- for the first time -- that less intensively managed British grazed grasslands have on average 50% more plant species and better soil health than intensively managed grassland. The new study could help farmers increase both biodiversity and soil health, including the amount of carbon in the soil of the British countryside.

Grazed grassland makes up a large proportion of the British countryside and is vital to farming and rural communities. This land can be perceived as only being about food production, but this study gives more evidence that it could be key to increasing biodiversity and soil health.

Researchers at the UK Centre for Ecology & Hydrology (UKCEH) studied 940 plots of grassland, comparing randomly selected plots which sampled the range of grassland management across Great Britain; from intensively- managed land with a few sown grassland species and high levels of soil phosphorus (indicating ploughing/reseeding and fertiliser and slurry application), to grassland with higher levels of species and lower levels of soil phosphorus. The plots were sampled as part of the UKCEH Countryside Survey, a nationally representative long-term dataset.

The study counted the number of plant species in sample areas and analysed co-located soil samples for numbers of soil invertebrates and carbon, nitrogen and phosphorus levels.

Researchers found that less intensively managed grassland had greater diversity of plant species and, strikingly, this correlated with better soil health, such as increased nitrogen and carbon levels and increased numbers of soil invertebrates such as springtails and mites.

In the same study, the researchers used the same methods to examine the plant diversity and soil from grasslands on 56 mostly beef farms from the Pasture Fed Livestock Association (PFLA) -- a farmer group that has developed standards to manage and improve soil and pasture health.

The researchers found that plots of land from PFLA farms had greater plant diversity -- on average an additional six plant species, including different types of grasses and herbaceous flowering plants, compared to intensively farmed plots from the Countryside Survey. In addition, grassland plants on these farms were often taller, a quality which is proven to be beneficial to butterflies and bees.

Pasture Fed Livestock Association grasslands did not yet show increased soil health, but the research indicated that this may be due to a time lag between increasing numbers of plant species and changes in soil health, particularly on farms which have been intensively managed in the past.

Lead author Dr Lisa Norton, Senior Scientist at UKCEH, says: "We've shown for the first time, on land managed by farmers for production, that a higher diversity of plants in grasslands is correlated with better soil health. This work also tells us that the Pasture Fed Livestock Association members are on the right track to increase biodiversity, though it may take longer to see improvements in soil health.

"Grassland with different types of plants able to grow tall and flower is associated with improved soil health measures, and is beneficial for creepy crawlies below and above ground. Having this abundance of life in our grasslands can in turn support small mammals and birds of prey, and farmers have told us that they are seeing voles and mice in their fields for the first time."

Dr Norton adds: "My hope for the future is that our grasslands can be managed less intensively -- with all the improvements in plant and animal biodiversity and soil health that brings -- but still remain productive for farmers."

Read more at Science Daily

Immune cells in ALS patients can predict the course of the disease

By measuring immune cells in the cerebrospinal fluid when diagnosing ALS, it is possible to predict how fast the disease may progress according to a study from Karolinska Institutet published in Nature Communications.

ALS is a rare, but fatal disease that affects the nerve cells and leads to paralysis of voluntary muscles and death. In a new study, researchers from Karolinska Institutet have discovered a way to predict the course of the disease in ALS patients.

Between March 2016 and March 2020, researchers collected fresh blood and cerebrospinal fluid from 89 patients in Stockholm who had recently been diagnosed with ALS. The patients were followed until October 2020.

The study shows that a high proportion of so-called effector T cells are associated with a low survival rate. At the same time, a high proportion of activated regulatory T cells indicate a protective role against the rapid disease progression. The findings provide new evidence for the involvement of T cells in the course of the disease and show that certain types of effector T cells accumulate in the cerebrospinal fluid of ALS patients.

"The study could contribute to the development of new treatments that target immune cells to slow down the course of the disease," says Solmaz Yazdani, a doctoral student at the Institute of Environmental Medicine at Karolinska Institutet and first author of the study.

The next step in her research is to study how T cells contribute to the course of the disease.

"We have plans to collect samples from these individuals to study changes in the immune cells over time. In addition, we want to study effector T cells in more detail to understand their role in ALS."

Read more at Science Daily

Stop counting cups: There's an ocean of difference in our water-drinking needs

A new study of thousands of people reveals a wide range in the amount of water people consume around the globe and over their lifespans, definitively spilling the oft-repeated idea that eight, 8-ounce glasses meet the human body's daily needs.

"The science has never supported the old eight glasses thing as an appropriate guideline, if only because it confused total water turnover with water from beverages and a lot of your water comes from the food you eat," says Dale Schoeller, a University of Wisconsin-Madison emeritus professor of nutritional sciences who has been studying water and metabolism for decades. "But this work is the best we've done so far to measure how much water people actually consume on a daily basis -- the turnover of water into and out of the body -- and the major factors that drive water turnover."

That's not to say the new results settle on a new guideline. The study, published today in the journal Science, measured the water turnover of more than 5,600 people from 26 countries, ages ranging from 8 days to 96 years old, and found daily averages on a range between 1 liter per day and 6 liters per day.

"There are outliers, too, that are turning over as much as 10 liters a day," says Schoeller, a co-author of the study. "The variation means pointing to one average doesn't tell you much. The database we've put together shows us the big things that correlate with differences in water turnover."

Previous studies of water turnover relied largely on volunteers to recall and self-report their water and food consumption, or were focused observations -- of, say, a small group of young, male soldiers working outdoors in desert conditions -- of questionable use as representative of most people.

The new research objectively measured the time it took water to move through the bodies of study participants by following the turnover of "labeled water." Study subjects drank a measured amount of water containing trackable hydrogen and oxygen isotopes. Isotopes are atoms of a single element that have slightly different atomic weights, making them distinguishable from other atoms of the same element in a sample.

"If you measure the rate a person is eliminating those stable isotopes through their urine over the course of a week, the hydrogen isotope can tell you how much water they're replacing and the elimination of the oxygen isotope can tell us how many calories they are burning," says Schoeller, whose UW-Madison lab in the 1980s was the first to apply the labeled-water method to study people.

More than 90 researchers were involved in the study, which was led by a group that includes Yosuke Yamada, a former UW-Madison postdoctoral researcher in Schoeller's lab and now section head of the National Institute of Biomedical Innovation, Health and Nutrition in Japan, and John Speakman, zoology professor at the University of Aberdeen in Scotland. They collected and analyzed data from participants, comparing environmental factors -- such as temperature, humidity and altitude of the participants' hometowns -- to measured water turnover, energy expenditure, body mass, sex, age and athlete status.

The researchers also incorporated the United Nations' Human Development Index, a composite measure of a country that combines life expectancy, schooling and economic factors.

Water turnover volume peaked for men in the study during their 20s, while women held a plateau from 20 through 55 years of age. Newborns, however, turned over the largest proportion daily, replacing about 28 percent of the water in their bodies every day.

Physical activity level and athletic status explained the largest proportion of the differences in water turnover, followed by sex, the Human Development Index, and age.

All things equal, men and women differ by about half a liter of water turnover. As a baseline of sorts, the study's findings expect a male non-athlete (but of otherwise average physical activity) who is 20 years old, weighs 70kg (154 pounds), lives at sea level in a well-developed country in a mean air temperature of 10 degrees C (50 Fahrenheit) and a relative humidity of 50%, would take in and lose about 3.2 liters of water every day. A woman of the same age and activity level, weighing 60 kg (132 pounds) and living in the same spot, would go through 2.7 liters (91 ounces).

Doubling the energy a person uses will push their expected daily water turnover up by about liter, the researchers found. Fifty kilograms more body weight adds 0.7 liters a day. A 50% increase in humidity pushes water use up by 0.3 liters. Athletes use about a liter more than non-athletes.

The researchers found "hunter-gatherers, mixed farmers, and subsistence agriculturalists" all had higher water turnover than people who live in industrialized economies. In all, the lower your home country's Human Development Index, the more water you go through in a day.

"That's representing the combination of several factors," Schoeller says. "Those people in low HDI countries are more likely to live in areas with higher average temperatures, more likely to be performing physical labor, and less likely to be inside in a climate-controlled building during the day. That, plus being less likely to have access to a sip of clean water whenever they need it, makes their water turnover higher."

The measurements will improve our ability to predict more specific and accurate future water needs, especially in dire circumstances, according to Schoeller.

"Look at what's going on in Florida right now, or in Mississippi -- where entire regions have been exposed by a calamity to water shortages," he says. "The better we understand how much they need, the better prepared we are to respond in an emergency."

And the better we can prepare for long-term needs and even notice short-term health concerns, the researchers believe.

"Determining how much water humans consume is of increasing importance because of population growth and growing climate change," says Yamada. "Because water turnover is related to other important indicators of health, like physical activity and body fat percent, it has potential as a biomarker for metabolic health."

Read more at Science Daily

Planet's rarest birds at higher risk of extinction

A new study finds that bird species with extreme or uncommon combinations of traits face the highest risk of extinction. The findings are published in the British Ecological Society journal Functional Ecology.

A new study led by researchers at Imperial College London finds that the most unique birds on the planet are also the most threatened. Losing these species and the unique roles they play in the environment, such as seed dispersal, pollination and predation, could have severe consequences to the functioning of ecosystems.

The study analysed the extinction risk and physical attributes (such as beak shape and wing length) of 99% of all living bird species, making it the most comprehensive study of its kind to date.

The researchers found that in simulated scenarios in which all threatened and near-threatened bird species became extinct, there would be a significantly greater reduction in the physical (or morphological) diversity among birds than in scenarios where extinctions were random.

Bird species that are both morphologically unique and threatened include the Christmas Frigatebird (Fregata andrewsi), which nests only on Christmas Island, and the Bristle-thighed Curlew (Numenius tahitiensis), which migrates from its breeding grounds in Alaska to South Pacific islands every year.

Jarome Ali, a PhD candidate at Princeton University who completed the research at Imperial College London and was the lead author of the research, said: "Our study shows that extinctions will most likely prune a large proportion of unique species from the avian tree. Losing these unique species will mean a loss of the specialised roles that they play in ecosystems.

"If we do not take action to protect threatened species and avert extinctions, the functioning of ecosystems will be dramatically disrupted."

In the study, the authors used a dataset of measurements collected from living birds and museum specimens, totalling 9943 bird species. The measurements included physical traits like beak size and shape, and the length of wings, tails and legs.

The authors combined the morphological data with extinction risk, based on each species' current threat status on the IUCN Red List. They then ran simulations on what would happen if the most threatened birds were to go extinct.

Although the dataset used in the study was able to show that the most unique birds were also classified as threatened on the Red List, it was unable to show what links uniqueness in birds to extinction risk.

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525-million-year-old fossil defies textbook explanation for brain evolution

Fossils of a tiny sea creature that died more than half a billion years ago may compel a science textbook rewrite of how brains evolved.

A study published in Science -- led by Nicholas Strausfeld,a Regents Professor in the University of Arizona Department of Neuroscience, and Frank Hirth, a reader of evolutionary neuroscience at King's College London -- provides the first detailed description of Cardiodictyon catenulum, a wormlike animal preserved in rocks in China's southern Yunnan province. Measuring barely half an inch (less than 1.5 centimeters) long and initially discovered in 1984, the fossil had hidden a crucial secret until now: a delicately preserved nervous system, including a brain.

"To our knowledge, this is the oldest fossilized brain we know of, so far," Strausfeld said.

Cardiodictyon belonged to an extinct group of animals known as armored lobopodians, which were abundant early during a period known as the Cambrian, when virtually all major animal lineages appeared over an extremely short time between 540 million and 500 million years ago. Lobopodians likely moved about on the sea floor using multiple pairs of soft, stubby legs that lacked the joints of their descendants, the euarthropods -- Greek for "real jointed foot." Today's closest living relatives of lobopodians are velvet worms that live mainly in Australia, New Zealand and South America.

A debate going back to the 1800s

Fossils of Cardiodictyon reveal an animal with a segmented trunk in which there are repeating arrangements of neural structures known as ganglia. This contrasts starkly with its head and brain, both of which lack any evidence of segmentation.

"This anatomy was completely unexpected because the heads and brains of modern arthropods, and some of their fossilized ancestors, have for over a hundred years been considered as segmented," Strausfeld said.

According to the authors, the finding resolves a long and heated debate about the origin and composition of the head in arthropods, the world's most species-rich group in the animal kingdom. Arthropods include insects, crustaceans, spiders and other arachnids, plus some other lineages such as millipedes and centipedes.

"From the 1880s, biologists noted the clearly segmented appearance of the trunk typical for arthropods, and basically extrapolated that to the head," Hirth said. "That is how the field arrived at supposing the head is an anterior extension of a segmented trunk."

"But Cardiodictyon shows that the early head wasn't segmented, nor was its brain, which suggests the brain and the trunk nervous system likely evolved separately," Strausfeld said.

Brains do fossilize

Cardiodictyon was part of the Chengjiang fauna, a famous deposit of fossils in the Yunnan Province discovered by paleontologist Xianguang Hou. The soft, delicate bodies of lobopodians have preserved well in the fossil record, but other than Cardiodictyon none have been scrutinized for their head and brain, possibly because lobopodians are generally small. The most prominent parts of Cardiodictyon were a series of triangular, saddle-shaped structures that defined each segment and served as attachment points for pairs of legs. Those had been found in even older rocks dating back to the advent of the Cambrian.

"That tells us that armored lobopodians might have been the earliest arthropods," Strausfeld said, predating even trilobites, an iconic and diverse group of marine arthropods that went extinct around 250 million years ago.

"Until very recently, the common understanding was 'brains don't fossilize,'" Hirth said. "So you would not expect to find a fossil with a preserved brain in the first place. And, second, this animal is so small you would not even dare to look at it in hopes of finding a brain."

However, work over the last 10 years, much of it done by Strausfeld, has identified several cases of preserved brains in a variety of fossilized arthropods.

A common genetic ground plan for making a brain

In their new study, the authors not only identified the brain of Cardiodictyon but also compared it with those of known fossils and of living arthropods, including spiders and centipedes. Combining detailed anatomical studies of the lobopodian fossils with analyses of gene expression patterns in their living descendants, they conclude that a shared blueprint of brain organization has been maintained from the Cambrian until today.

"By comparing known gene expression patterns in living species," Hirth said, "we identified a common signature of all brains and how they are formed."

In Cardiodictyon, three brain domains are each associated with a characteristic pair of head appendages and with one of the three parts of the anterior digestive system.

"We realized that each brain domain and its corresponding features are specified by the same combination genes, irrespective of the species we looked at," added Hirth. "This suggested a common genetic ground plan for making a brain."

Lessons for vertebrate brain evolution

Hirth and Strausfeld say the principles described in their study probably apply to other creatures outside of arthropods and their immediate relatives. This has important implications when comparing the nervous system of arthropods with those of vertebrates, which show a similar distinct architecture in which the forebrain and midbrain are genetically and developmentally distinct from the spinal cord, they said.

Strausfeld said their findings also offer a message of continuity at a time when the planet is changing dramatically under the influence of climatic shifts.

"At a time when major geological and climatic events were reshaping the planet, simple marine animals such as Cardiodictyon gave rise to the world's most diverse group of organisms -- the euarthropods -- that eventually spread to every emergent habitat on Earth, but which are now being threatened by our own ephemeral species."

Read more at Science Daily

Astronomers observe intra-group light -- the elusive glow between distant galaxies

An international team of astronomers have turned a new technique onto a group of galaxies and the faint light between them -- known as 'intra-group light' -- to characterise the stars that dwell there.

Lead author of the study published in MNRAS, Dr Cristina Martínez-Lombilla from the School of Physics at UNSW Science, said "We know almost nothing about intra-group light.

"The brightest parts of the intra-group light are ~50 times fainter than the darkest night sky on Earth. It is extremely hard to detect, even with the largest telescopes on Earth -- or in space."

Using their sensitive technique, which eliminates light from all objects except that from the intra-group light, the researchers not only detected the intra-group light but were able to study and tell the story of the stars that populate it.

"We analysed the properties of the intra-group stars -- those stray stars between the galaxy groups. We looked at the age and abundance of the elements that composed them and then we compared those features with the stars still belonging to galaxy groups," Dr Martínez-Lombilla said.

"We found that the intra-group light is younger and less metal-rich than the surrounding galaxies."

Rebuilding the story of intra-group light

Not only were the orphan stars in the intra-group light 'anachronistic' but they appeared to be of a different origin to their closest neighbours. The researchers found the character of the intra-group stars appeared similar to the nebulous 'tail' of a further away galaxy.

The combination of these clues allowed the researchers to rebuild the history -- the story -- of the intra-group light and how its stars came to be gathered in their own stellar orphanage.

"We think these individual stars were at some points stripped from their home galaxies and now they float freely, following the gravity of the group," said Dr Martínez-Lombilla. "The stripping, called tidal stripping, is caused by the passage of massive satellite galaxies -- similar to the Milky Way -- that pull stars in their wake."

This is the first time the intra-group light of these galaxies has been observed.

"Unveiling the quantity and origin of the intra-group light provides a fossil record of all the interactions a group of galaxies has undergone and provides a holistic view of the system's interaction history," Dr Martínez-Lombilla said.

"Also, these events occurred a long time ago. The galaxies [we're looking at] are so far away, that we're observing them as they were 2.5 billion years ago. That is how long it takes for their light to reach us."

By observing events from a long time ago, in galaxies so far away, the researchers are contributing vital datapoints to the slow-burning evolution of cosmic events.

Tailored image treatment procedure

The researchers pioneered a unique technique to achieve this penetrating view.

"We have developed a tailored image treatment procedure that allows us to analyse the faintest structures in the Universe," said Dr Martínez-Lombilla.

"It follows the standard steps for the study of faint structures in astronomical images -- which implies 2D modelling and the removal of all light except that coming from the intra-group light. This includes all the bright stars in the images, the galaxies obscuring the intra-group light and a subtraction of the continuum emission from the sky.

"What makes our technique different is that it is fully Python-based so it is very modular and easily applicable to different sets of data from different telescopes rather than being just useful for these images.

"The most important outcome is that when studying very faint structures around galaxies, every step in the process counts and every undesirable light should be accounted for and removed. Otherwise, your measurements will be wrong.

The techniques presented in this study are a pilot, encouraging future analyses of intra-group light, Dr Martínez-Lombilla said.

"Our main long-term goal is to extend these results to a large sample of group of galaxies. Then we can look at statistics and find out the typical properties regarding the formation and evolution of the intra-group light and these extremely common systems of groups of galaxies.

Read more at Science Daily

Picky eaters are put off by food depending on plateware color

Academics have examined the effect of colour among picky and non-picky eaters, in a first-of-its-kind study.

Previous research has demonstrated that the smell and texture of food can affect how it tastes for picky eaters, but little is known about other senses.

A team from the University of Portsmouth has discovered the colour of the bowl in which food is served also influences taste perception.

The experiment comprised nearly 50 people to measure their food neophobia, which is a reluctance to eat or try new food. The participants, who were divided into picky and non-picky eaters, then tasted the same snacks served in red, white and blue bowls.

Results revealed that both the perceived saltiness and desirability of the foods were influenced by colour in the picky group, but not the non-picky group.

Specifically, the snack was rated as higher in saltiness in the red and blue versus white bowl, and least desirable when served in the red bowl. In the UK, salty snacks are often sold in blue packaging, and the team believe that this might explain some of the saltiness findings.

Dr Lorenzo Stafford, an olfactory (sense of smell) researcher in the Department of Psychology at the University of Portsmouth, said: "Having restricted diets can lead to nutritional deficiencies as well as health problems like heart disease, poor bone health and dental issues. There is also a social cost because normally enjoyable moments between family members can easily turn into stressful, anxious, and conflict-causing situations when picky eaters feel ashamed or pressured to eat food.

"That is why it's important to understand the factors that act to 'push and pull' this behaviour."

Picky eating behaviour is usually categorised as having a limited diet, specific food preparation, strong dislikes and difficulty accepting new foods. Across a lifespan, a picky eater will generally consume fewer than 20 different food items.

The paper, published in the Food Quality and Preference journal, says this study is believed to be the first to provide insight into the interaction between colour and taste perception in adult picky and non-picky eaters and reveal a difference in the way that colour affects the perception of food in picky eaters.

It recommends further research to see if these findings extend beyond the food and colours tested here.

"This knowledge could be useful for those trying to expand the repertoire of foods," added Dr Stafford.

"For example, if you wanted to encourage a picky eater to try more vegetables well known to be viewed as bitter, you could attempt to serve them on a plate or bowl that is known to increase sweetness.

Read more at Science Daily