Meanders in river beds help the climate

It takes about 8500 years for a grain of sand from the Andes to be washed across the Argentine lowlands into the Río Paraná. The 1200-kilometer journey in the river called Río Bermejo is interrupted by many stops in river floodplains, where the grain is deposited, sometimes over thousands of years, and then washed free again. The sand is accompanied by organic carbon, washed in from soil and plants. The transport in water thus gains relevance for the climate: Rivers carry the carbon, which was previously removed from the atmosphere via photosynthesis, as sediment into the sea, where it is stored for thousands of years without harming the climate.

Researchers at the GFZ German Research Centre for Geosciences have now quantified the individual processes of the journey for the first time and report on them in the journal Nature Geoscience. An important result of the work: It is in particular undisturbed meandering sections of a river where carbon is deposited and reabsorbed, and then transported further into the sea. In river sections with straight, stable banks, on the other hand, only the suspended particle load passes through, while the carbon in the river floodplains is slowly decomposed again to CO2 by microorganisms. GFZ working group leader Dirk Sachse says, "The Río Bermejo was an ideal natural laboratory for us because it has no significant tributaries." Sachse is also director of the "Landscapes of the Future" topic in the Helmholtz program "Changing Earth -- Sustaining Our Future." He says, "This means that natural river courses that have space to erode floodplains can remove more carbon from the atmosphere than straight river sections. In this respect, straightening of rivers by humans could also contribute to the increase in atmospheric CO2 concentration. What's exciting now is answering the question of whether we can help the climate by giving rivers more space again and not impeding natural river meandering."

The international team led by first author Marisa Repasch of GFZ studied the processes in the river and its floodplains with a diverse set of instruments. Analyses of cosmogenic beryllium-10 content, for example, indicated the duration of sediment transport. Dating based on the unstable carbon isotope 14C, in turn, allowed conclusions to be drawn about the age of the particles of organic origin. During fieldwork in Argentina, samples were taken from the river at multiple stations along the source-to-sink pathway. "Naturally meandering rivers erode material from floodplains and transport it to the sea, where it remains for a long time," says Marisa Repasch, summarizing the results, "in contrast, artificially stabilized river courses are far less effective carbon sinks."

From Science Daily

New species of human ancestor named: Homo bodoensis

An international team of researchers, led by University of Winnipeg palaeoanthropologist Dr. Mirjana Roksandic, has announced the naming of a new species of human ancestor, Homo bodoensis. This species lived in Africa during the Middle Pleistocene, around half a million years ago, and was the direct ancestor of modern humans.

The Middle Pleistocene (now renamed Chibanian and dated to 774,000-129,000 years ago) is important because it saw the rise of our own species (Homo sapiens) in Africa, our closest relatives, and the Neanderthals (Homo neanderthalensis) in Europe.

However, human evolution during this age is poorly understood, a problem which paleoanthropologists call "the muddle in the middle." The announcement of Homo bodoensis hopes to bring some clarity to this puzzling, but important chapter in human evolution.

The new name is based on a reassessment of existing fossils from Africa and Eurasia from this time period. Traditionally, these fossils have been variably assigned to either Homo heidelbergensis or Homo rhodesiensis, both of which carried multiple, often contradictory definitions.

"Talking about human evolution during this time period became impossible due to the lack of proper terminology that acknowledges human geographic variation" according to Roksandic, lead author on the study.

Recently, DNA evidence has shown that some fossils in Europe called H. heidelbergensis were actually early Neanderthals, making the name redundant. For the same reason, the name needs to be abandoned when describing fossil humans from east Asia according to co-author, Xiu-Jie Wu (Institute of Vertebrate Paleontology and Paleoanthropology, Beijing, China).

Further muddling the narrative, African fossils dated to this period have been called at times both H. heidelbergensis and H. rhodesiensis. H. rhodesiensis is poorly defined and the name has never been widely accepted. This is partly due to its association with Cecil Rhodes and the horrendous crimes carried out during colonial rule in Africa -- an unacceptable honour in light of the important work being done toward decolonizing science.

The name "bodoensis" derives from a skull found in Bodo D'ar, Ethiopia, and the new species is understood to be a direct human ancestor. Under the new classification, H. bodoensis will describe most Middle Pleistocene humans from Africa and some from Southeast Europe, while many from the latter continent will be reclassified as Neanderthals,

The co-first author Predrag Radovic (Faculty of Philosophy, University of Belgrade, Serbia) says, "Terms need to be clear in science, to facilitate communication. They should not be treated as absolute when they contradict the fossil record."

Read more at Science Daily

Fossil dental exams reveal how tusks first evolved and why they are unique only to mammals

Most people picture an elephant when imagining animals with tusks. But many other animals have tusks including warthogs, hippopotamuses, Arctic-dwelling walruses, and even a five-pound, guinea pig looking animal called hyraxes. Though the size of the animal and their tusks can vary they all have one unique thing in common in that they are only found on mammals -- there are no known fish, reptiles, or birds with tusks. Despite being an iconic feature of modern and fossil mammals the mystery remains of what evolutionary steps led to the development of this dental phenomenon and why are mammals the only animals today with tusks?

In a new paper published October 27 in the Proceedings of the Royal Society B researchers trace the first tusks back to ancient mammal relatives that lived before the dinosaurs and shed light on the evolution of mammalian tusks by first defining what makes a tusk a tusk.

"Tusks are this very famous anatomy, but until I started working on this study, I never really thought about how tusks are restricted to mammals," said lead author Megan Whitney, postdoctoral fellow in the Department of Organismic and Evolutionary Biology, Harvard University.

"We were able to show that the first tusks belonged to animals that came before modern mammals, called dicynodonts," said Kenneth Angielczyk, co-author and curator at Chicago's Field Museum. "They're very weird animals."

Dicynodonts, though not mammals, are distant relatives and are more closely related to mammals than dinosaurs and other reptiles. Dicynodonts lived between 270-201 million years ago and included a diverse range of animals from tiny rat-like dicynodonts to huge elephant-sized dicynodonts. They are known for having a very peculiar arrangement of teeth. A defining feature of these animals, first discovered 176 years ago, is the protruding tusks in their upper jaws. Most had two upper tusks that came down from the canine position, but they rarely had additional teeth. Instead, dicynodonts had a beak at the front of their mouths that was made of keratin and resembled a turtles beak.

The researchers were taking a lunch break during a paleontological dig when they got the idea for the study. "We were sitting in the field in Zambia, and there were dicynodont teeth everywhere," recalls Whitney. "I remember Ken picking them up and asking how come they were called tusks, because they had features that tusks don't have."

Not all protruding teeth are technically tusks. "For this paper, we had to define a tusk, because it's a surprisingly ambiguous term," said Whitney. The researchers determined that for a tooth to be a tusk it must extend out from the mouth, be made entirely of dentine -- lacking enamel found on most mammals' teeth, and is ever-growing.

The researchers performed paleohistology (the study of fossil tissues) on paper-thin slices of fossilized teeth from 19 dicynodont specimens, representing ten different species. They used micro-CT to examine how the teeth attached to the skull and to see if there was any evidence of continuous growth.

Some of the dicynodont tusks that the team observed in Zambia didn't seem to fit the definition of a tusk either -- they were coated in enamel instead of dentine. "There are many different kinds of dicynodonts and they appear to mostly all have tusks," said Whitney, "however, when you look at the micro structural details they're very different in those groups." Enamel teeth are tougher than dentine but because of the geometry of how teeth grow in the jaw, if you want teeth that keep growing throughout your life, you can't have a complete enamel covering. Animals like humans evolved durable but hard-to-fix teeth -- there is no replacement for the loss of an adult tooth. Tusks are less durable than enamel-coated teeth, but they grow continuously, even if they get damaged. "Enamel-coated teeth are a different evolutionary strategy than dentine-coated tusks, it's a trade-off," says Whitney.

Analysing the histological thin sections of dicynodont specimens from South Africa, Antarctica, Zambia, and Tanzania the researchers found that, much like human teeth, these animals appeared to reduce the amount of replacement teeth at the canine position and had a soft tissue attachment to the jaw. Interestingly, this is a combination of features that is unique to mammals. Mammals, like humans, replace baby teeth with adult teeth only once unlike most other vertebrates -- for instance sharks have continuous teeth production. Mammal teeth are attached to the jaw by gomphosis which is a soft-tissue, or ligament, attachment. Most vertebrate teeth, however, are attached to the jaw by ankylosis, which is a hard-tissue fusion of bone to tooth.

"If you have these two things, a reduced amount of tooth replacement and a soft-tissue attachment, an ever-growing tooth allows the animal to get around the fact that it cannot replace the tooth. Instead it evolves to continuously deposit the same tooth tissues," said Whitney. "And as the animal continues to deposit the tissue, the tooth begins to move outside of the mouth to become functional."

The researchers found that true tusk evolution only occurred at a later stage of evolution in this group -- early members of this group had a big tooth rather than a true tusk. Late in their evolutionary history dicynodonts evolved a true tusk that was ever growing, and surprisingly did so convergently in multiple different kinds of dicynodonts. "I kind of expected there to be one point in the family tree where all the dicynodonts started having tusks, so I thought it was pretty shocking that we actually see tusks evolve convergently," said Whitney. "This is a similar story to what we see in elephant evolution in that it mirrors a lot of the patterns that have been studied on how elephants got their tusks."

"Dicynodonts were the most abundant and diverse vertebrates on land just before dinosaur times, and they're famous for their 'tusks.' The fact that in reality only a few have true tusks, and the rest have big teeth, is a beautiful example of evolution we can document. We can see how to build a tusk!" said co-author Brandon Peecook, curator at the Idaho Museum of Natural History.

The researchers say that the study, which shows the earliest known instance of true tusks, could help scientists better understand how evolution works.

"Tusks have evolved a number of times, which makes you wonder how -- and why? We now have good data on the anatomical changes that needed to happen for dicynodonts to evolve tusks. For other groups, like warthogs or walruses, the jury is still out," said co-author Christian Sidor, curator at the University of Washington Burke Museum.

The various kinds of teeth animals have evolved can tell scientists about the pressures those animals faced that could have produced those teeth. For instance tusks can function in a variety of ways including defense, competition, burrowing, sexual selection, and even assist with locomotion -- as in the walrus which uses its tusks to hoist itself upon to the ice from the water. A continuously growing tusk may have allowed these dicynodonts to overcome the challenges of only having one set of replacement teeth throughout their lives.

"We don't really know what functions the dicynodonts tusks may have had because we can't observe them and see what they were doing with them," said Whitney. "That's a lingering question about dicynodonts, even more so now."

Read more at Science Daily

Juno peers deep into Jupiter’s colorful belts and zones

Leicester study of data captured in orbit around Jupiter has revealed new insights into what's happening deep beneath the gas giant's distinctive and colourful bands.

Data from the microwave radiometer carried by NASA's Juno spacecraft shows that Jupiter's banded pattern extends deep below the clouds, and that the appearance of Jupiter's belts and zones inverts near the base of the water clouds. Microwave light allows planetary scientists to gaze deep beneath Jupiter's colourful clouds, to understand the weather and climate in the warmer, darker, deeper layers.

At altitudes shallower than five bars of pressure (or around five times the average atmospheric pressure on Earth), the planet's belts shine brightly in microwave light, whereas the zones are dark. But everything changes at higher pressures, at altitudes deeper than 10 bars, giving scientists a glimpse of an unexpected reversal in the meteorology and circulation.

Dr Leigh Fletcher, Associate Professor in Planetary Science at the University of Leicester and Participating Scientist for the Juno mission, is lead author of the study, published in the Journal of Geophysical Research-Planets. He said:

"One of Juno's primary goals was to peer beneath the cloudy veil of Jupiter's atmosphere, and to probe the deeper, hidden layers.

"Our study has shown that those colourful bands are just the 'tip of the iceberg', and that the mid-latitude bands not only extend deep, but seem to change their nature the further down you go.

"We've been calling the transition zone the jovicline, and its discovery has only been made possible by Juno's microwave instrument."

Among Jupiter's most notable attributes is its distinctive banded appearance. Planetary scientists call the light, whiteish bands zones, and the darker, reddish ones belts. Jupiter's planetary-scale winds circulate in opposite direction, east and west, on the edges of these colourful stripes. A key question is whether this structure is confined to the planet's cloud tops, or if the belts and zones persist with increasing depth.

An investigation of this phenomenon is one of the primary objectives of NASA's Juno mission, and the spacecraft carries a specially-designed microwave radiometer to measure emission from deep within the Solar System's largest planet for the first time.

The Juno team utilise data from this instrument to examine the nature of the belts and zones by peering deeper into the Jovian atmosphere than has ever previously been possible.

Juno's microwave radiometer operates in six wavelength channels ranging from 1.4 cm to 50 cm, and these enable Juno to probe the atmosphere at pressures starting at the top of the atmosphere near 0.6 bars to pressures exceeding 100 bars, around 250 km deep.

At the cloud tops, Jupiter's belts appear bright with microwave emission, while the zones remain dark. Bright microwave emission either means warmer atmospheric temperatures, or an absence of ammonia gas, which is a strong absorber of microwave light.

This configuration persists down to approximately five bars. And at pressures deeper than 10 bars, the pattern reverses, with the zones becoming microwave-bright and the belt becoming dark. Scientists therefore believe that something -- either the physical temperatures or the abundance of ammonia -- must therefore be changing with depth.

Dr Fletcher terms this transition region between five and 10 bars the jovicline, a comparison to the thermocline region of Earth's oceans, where seawater transitions sharply from relative warmth to relative coldness. Researchers observe that the jovicline is nearly coincident with a stable atmospheric layer created by condensing water.

Dr Scott Bolton, of NASA's Jet Propulsion Laboratory (JPL), is Principal Investigator (PI) for the Juno mission. He said:

"These amazing results provide our first glimpse of how Jupiter's famous zones and belts evolve with depth, revealing the power of investigating the giant planet's atmosphere in three dimensions."

There are two possible mechanisms that could be responsible for the change in brightness, each implying different physical conclusions.

One mechanism is related to the distribution of ammonia gas within the belts and zones. Ammonia is opaque to microwaves, meaning a region with relatively less ammonia will shine brighter in Juno's observations. This mechanism could imply a stacked system of opposing circulation cells, similar to patterns in Earth's tropics and mid-latitudes.

These circulation patterns would provide sinking in belts at shallow depths and upwelling in belts at deeper levels -- or vigorous storms and precipitation, moving ammonia gas from place to place.

Another possibility is that the gradient in emission corresponds to a gradient in temperature, with higher temperatures resulting in greater microwave emission.

Temperatures and winds are connected, so if this scenario is correct, then Jupiter's winds may increase with depth below the clouds until we reach the jovicline, before tapering off into the deeper atmosphere -- something that was also suggested by NASA's Galileo probe in 1995, which measured windspeeds as it descended under a parachute into the clouds of Jupiter.

Read more at Science Daily

The early bird gets…the truffle? Birds hunt for fungi, too

Humans like truffles, as do many mammals. Now new evidence suggests that birds may also seek out and disperse these ecologically important fungi.

A study conducted by University of Florida researchers found that two common ground-dwelling bird species in Patagonia regularly consume truffles and pass on viable truffle spores through their feces.

"Truffles are essentially mushrooms that grow underground. Unlike aboveground mushrooms, which release their spores into the air, truffles depend on animals consuming them to spread their spores," said Matthew E. Smith, senior author on the study and an associate professor in the UF/IFAS plant pathology department.

"Previously, it was assumed that only mammals consumed and dispersed truffle spores, so our study is the first to document birds doing this as well," said Marcos Caiafa, first author of the study, who recently received a doctorate in plant pathology from the UF/IFAS College of Agricultural and Life Sciences. Smith was Caiafa's dissertation adviser.

The term "truffle" includes hundreds of species of underground fungi, only a few of which are the truffles people associate with high-end cuisine. While non-culinary truffles may not appeal to human foodies, each has evolved to attract different animals that can assist in its spread.

The spreading of truffle spores is an important part of a healthy forest ecosystem, Smith said, as many tree species have a symbiotic relationship with truffles, which colonize the roots of the trees.

"These fungi form mycorrhizas, a relationship whereby the fungus helps the plant take up nutrients in exchange for sugars from the plant," explained Caiafa, who is now a postdoctoral researcher at the University of California, Riverside.

The bird species they studied -- chucao tapaculos and black-throated huet-huets -- not only eat truffles but appear to search them out specifically. In the past these birds were known to eat invertebrates, seeds and fruits, but their consumption of fungi was not previously documented, the researchers said.

"The questions about birds and truffles emerged during an earlier research project in Patagonia. We are working in the forest, raking the soil and digging up the truffles, and we notice these birds keep following us around and checking out the areas where we had disturbed the soil. Then we find truffles with chunks pecked out of them. Marcos even saw a bird eat a truffle right in front of him. All of this led us to ask, are these birds hunting for truffles?" Smith said.

To confirm this hypothesis, the research team collected the droppings of chucao tapaculos and black-throated huet-huets and tested them for truffle DNA. They found truffle DNA in 42% of chucao tupaculo and 38% of huet-huet feces. They also used a special microscope technique, fluorescent microscopy, to confirm that the spores in the feces were viable, suggesting that the birds are spreading truffles to new areas.

"DNA-based diet analysis is exciting because it provides new insights into interactions between organisms that would otherwise be difficult to directly observe," said Michelle Jusino, one of the study's co-authors and a former postdoctoral researcher in Smith's lab.

"And, because sampling feces does not negatively impact the target species, I think these methods are invaluable for studying and protecting both common and rare species in the future," said Jusino, who is now a research biologist with the U.S. Forest Service Northern Research Station's Center for Forest Mycology Research.

The study's authors think that some truffles in Patagonia may have evolved to attract birds.

"Some of truffles that the birds eat are brightly colored and resemble local berries. Our future research may look to see if there is an evolutionary adaptation there -- that the truffles have evolved to look more like the berries that the birds also eat," Smith said.

Read more at Science Daily

Runoff, sediment flux in High Mountain Asia could limit food, energy for millions

Rivers flowing from the Tibetan Plateau and the surrounding high Asian mountains which support one-third of the world's population have experienced rapid increases in annual water and sediment runoff since the 1990s, and the volume of sediment washed downstream could more than double by 2050 under the worst-case scenario, a team of scientists has found.

The cause is "amplified warming": Since 1950, the High Mountain Asia area, or the region of Asia containing five mountain ranges including the Himalaya and Hindu Kush around the Tibetan Plateau, has warmed by about 2 degrees Celsius, twice the amount of warming worldwide. That warming is precipitating more glacier melt, permafrost thaw while annual rainfall is also increasing, the researchers note.

"These findings have far-reaching implications for the region's hydropower, food and environmental security," the researchers observe. The findings also highlight the under-appreciated importance of sediment fluxes and have implications for potential changes in the global carbon cycle, they add.

The research, published today in the journal Science, is led by the National University of Singapore and includes three researchers from the University of Colorado Boulder, including Irina Overeem, Jaia Syvitski and Albert Kettner, all researchers in the Institute of Arctic and Alpine Research. Overeem is also a CU Boulder associate professor of geological sciences, and Syvitski is professor emeritus of geological sciences.

The scientists analyzed observational data of runoff and sediment fluxes from 28 headwater basins over the past six decades.

Sediment flux is the mass of sediment that passes through a specific point in a river basin over a given time period, "like truckloads of sand being transported, in this case by water," Overeem said. Although river runoff, the amount of water entering a river system, and sediment flux are both increasing, they are rising at different rates.

In the river basins the scientists studied, runoff increased by about 5% per decade, while sediment flux increased about 12% per decade.

Overeem explained the variability is affected in two ways: "With glacial melt and permafrost thaw there are new sources of sediment, that previously had been frozen in place in the landscape now can slump into the river. In addition, if more rainfall triggers bigger floods, you suddenly have exceeded a threshold and you can pick up so much more sediment" compared to average conditions. "If you increase the source and the proportion of a couple of these extreme events, you'll get disproportionally much more sediment. So that is maybe what's going on in this system."

River-borne sediment can benefit highly populated areas like Bangladesh, where sediment helps maintain the coastal zone. But in other areas such as Tibet or Nepal, which have hydro-electric power plants, rising levels of sediment can wear out the dams' turbines and fill reservoirs with sand and silt.

By harming existing or planned hydropower projects and reducing irrigation capacity, rising sediment fluxes can thus "threaten the region's food and energy security," the authors write. Additionally, the rising levels of sediment, which can carry nutrients, pollutants and organic carbon, can have implications for water quality and flooding, potentially affecting millions of people.

Research on the High Mountain Asia watershed was facilitated by the area's unusually good, long-term records of streamflow and sediment flux, Overeem said, adding that datasets of similar quality do not exist for Greenland or the whole Arctic.

In the Arctic, scientists have also recorded increases in water discharge from melting ice and increasing rainfall but have few measurements of sediment flux.

Read more at Science Daily

The goal in mind

Scientists discover the brain's internal goal map enabling animals to navigate precisely to a chosen destination.

Animals including rodents and humans can navigate to a desired location by relying on the brain's internal cognitive map. While previous studies have identified specialized neurons that help us identify our own position and direction in space, whether the brain can process a precise estimate of a future target location has been a long-standing question. Scientists at the Max Planck Institute for Brain Research in Frankfurt have now discovered a neural code for spatial goals, demonstrating the existence of the brain's goal map guiding us toward a remote destination over space and time.

An internal compass

To perform a simple daily chore such as planning a trip to a local supermarket, you need to visualize the supermarket in your mind while you are still at home so that your brain can compute the best route for the upcoming journey. But how can the brain's spatial map simultaneously represent two locations in space -- your home that can be perceived with most of your senses, and the supermarket that is located beyond the range of your sensory perception? Neuroscientists have grappled with this question for the last 50 years.

"Since the Nobel prize winning discovery of place cells in 1971 by John O'Keefe and colleagues, spatial navigation research has primarily focused on the properties of neurons tuned to the animal's instantaneous position or direction," says Hiroshi Ito, research group leader at the Max Planck Institute for Brain Research who headed the new study published in Nature. Previous research in the last decades has provided us with a better understanding of how we can keep track of our position and direction in space. However, the evidence for goal estimation -- another fundamental aspect of spatial navigation -- has almost entirely been missing so far.

"Our present work addressed this puzzle by showing that future goals are represented as a pattern of neural activity resembling the ones during previous visits to a target location (e.g. supermarket). For example, a specific pattern of neural activity is observed when an animal visits a particular location in space. However, we found that this activity pattern can re-emerge merely upon the animal's decision to target the same location as a navigational goal, irrespective of where the animal is actually located," says Ito.

"We designed a task in which a rat needs to navigate to a remote location where a reward is provided. Notably, the reward location keeps changing, which ensures that the rat continuously updates its goal locations," explains Raunak Basu, the postdoc in the Ito lab and first author of the new study. As a candidate brain region representing a future goal, the scientists focused on the orbitofrontal cortex (OFC) -- a subregion of the prefrontal cortex -- that is thought to be involved in decision making, yet remains relatively unexplored from the aspect of spatial navigation.

Deciphering a neural code for future goals

To investigate neural patterns in the OFC, the researchers simultaneously measured the activity of hundreds of neurons. "We achieved this by using custom-built 3-D printed recording devices that can insert up to 60 ultra-thin wires (called tetrodes) in the rat's brain. These devices enabled us to monitor OFC neural activity patterns from when the rats were about to start their journey until they reached the goal location. With the help of statistical decoding techniques, we confirmed that these patterns share significant similarities, demonstrating that the future goal is represented in the OFC throughout the duration of navigation" says Basu.

Perturbation of OFC neurons leads to navigation errors

Fueled by their discovery, Basu and colleagues asked whether the activity of OFC neurons causally influences the animal's destination. To this end, they perturbed the activity of neurons in the OFC by applying pulsed laser light at the start of the journey. "I was most surprised to see that the rat that had been performing the navigation task almost perfectly, suddenly upon perturbation, ignorantly walked past a correct goal and headed to an incorrect location," recalls Basu. "This navigation error was reversible once the perturbation stopped, suggesting that the impairment is not due to a general loss of goal memory."

Read more at Science Daily

Why do humans possess a twisted birth canal?

In most women, the upper part, or inlet, of the birth canal has a round or transversely (left-to-right) oval shape, which is considered ideal for parturition, but it is unknown why the lower part of the birth canal has a pronounced longitudinally (front-to-back) oval shape. This twisted shape typically requires the Baby to rotate when passing through the narrow birth canal, which further increases the risk of birth complications.

In comparison with humans, apes have a relatively easy birth pattern that does not require rotation of the baby thanks to the longitudinally oval shape of the birth canal both at its inlet and the outlet. "For giving birth, it would be much easier to have a uniformly shaped birth canal also in our species," says Katya Stansfield, a specialist in biomechanics. Instead, the twisted human shape requires a complex, rotational birth mechanism: The baby needs to rotate to align the longest dimension of its head with the widest dimension of each plane of the birth canal. Misalignment can lead to obstructed labour and result in health risks for both mother and baby.

A research team of evolutionary biologists and engineers from the University of Vienna, the Konrad Lorenz Institute for Evolution and Cognition Research in Klosterneuburg and the University of Porto hypothesised that the support function of the pelvic floor muscles, which are suspended across the lower pelvis and also play an important role in sexual function and continence, may have influenced the evolution of the shape of the birth canal. The team carried out extensive biomechanical modelling of the pelvic floor and found that the highest deformation, stress, and strain occur in pelvic floors with a circular or transverse-oval shape, whereas a longitudinally oval elongation increases pelvic floor stability. "Our results demonstrate that the longitudinally oval lower birth canal is beneficial in terms of stability," says Katya Stansfield. "However, this outcome prompted us to ask why the pelvic inlet in humans is not also elongated longitudinally," elaborates Barbara Fischer, an evolutionary biologist.

Traditionally, it has been assumed that the transverse dimension of the human pelvis is constrained by the efficiency of upright locomotion. "We argue that the transverse elongation of the pelvic inlet has evolved because of the limits on the front-to-back diameter in humans imposed by balancing upright posture, rather than by the efficiency of the bipedal locomotion," says Philipp Mitteroecker, who was also involved in this study. A longitudinally deeper inlet would require greater pelvic tilt and lumbar lordosis, which would compromise spine health and the stability of upright posture. These different requirements of the pelvic inlet and outlet likely have led to the evolution of a twisted birth canal, requiring human babies to rotate during birth.

From Science Daily

Astronomers discover massive galaxy 'shipyard' in the distant universe

Even galaxies don't like to be alone. While astronomers have known for a while that galaxies tend to congregate in groups and clusters, the process of going from formation to friend groups has remained an open question in cosmology.

In a paper published in the Astronomy & Astrophysics Journal, an international team of astronomers reports the discovery of a group of objects that appear to be an emerging accumulation of galaxies in the making -- known as a protocluster.

"This discovery is an important step toward reaching our ultimate goal: understanding the assembly of galaxy clusters, the most massive structures that exist in the universe," said Brenda Frye, an associate professor of astronomy at the University of Arizona's Steward Observatory and a co-author of the study.

The Milky Way, home to our solar system, belongs to a galaxy cluster known as the Local Group, which in turn is a part of the Virgo supercluster. But what did a supercluster such as Virgo look like 11 billion years ago?

"We still know very little about protoclusters, in part because they are so faint, too faint to be detected by optical light," Frye said. "At the same time, they are known to radiate brightly in other wavelengths such as the sub-millimeter."

Initially discovered by the European Space Agency's Planck telescope as part of an all-sky survey, the protocluster described in the new paper showed up prominently in the far-infrared region of the electromagnetic spectrum. Sifting through a sample of more than 2,000 structures that could be in the process of becoming clusters, researchers came across a protocluster designated as PHz G237.01+42.50, or G237 for short. The observations looked promising, but to confirm its identity required follow-up observations with other telescopes.

Led by Mari Polletta at the National Institute for Astrophysics in Milan, Italy, the team conducted observations using the combined power of the Large Binocular Telescope in Arizona, which is managed by UArizona, and the Subaru Telescope in Japan. The team identified 63 galaxies belonging to the G237 protocluster. The original discovery was published in a previous paper, and follow-up observations were also obtained using archival data, the Herschel Space Observatory and the Spitzer Space Telescope.

"You can think of galaxy protoclusters such as G237 as a galaxy shipyard in which massive galaxies are being assembled, only this structure existed at a time when the universe was 3 billion years old," Frye said. "At the same time, the genealogy may be closer than you think. Because the universe is homogeneous and the same in all directions, we think that the Milky Way may have docked at a protocluster node similar to G237 when it was very young."

At first, observations of G237 implied a total star formation rate that was unrealistically high, and the team struggled to make sense of the data. The G237 protocluster seemed to be forming stars at a rate of 10,000 times that of the Milky Way. At that rate, the protocluster would be expected to rapidly use up its stellar fuel and subsequently settle down into a complex system similar to the Virgo supercluster.

"Each of the 63 galaxies discovered so far in G237 was like a star factory in overdrive," Frye said. "It's as if the galaxies were working on overtime to the assemble stars. The rate of production was unsustainable. At such a pace, the supply chains are expected to break in the near future, and in a way that permanently shuts down the galaxy shipyard."

Such high yields could only be maintained by a continuous injection of fuel, which for stars is hydrogen gas. Frye said that would require an efficient and unbroken supply chain that drew in unreasonably large amounts of fresh gas to fuel the star-forming factories.

"We don't know where that gas was coming from," she said.

Later, the team discovered that some of what it was seeing came from galaxies unrelated to the protocluster, but even after the irrelevant observations were removed, the total star formation rate remained high, at least 1,000 solar masses per year, according to Poletta. In comparison, the Milky Way produces about one solar mass each year.

"The picture we have pieced together now is that of a successful galaxy shipyard, which is working at high efficiency to assemble galaxies and the stars within them and has an energy supply that is more sustainable," Frye said.

All galaxies in the universe are part of a giant structure that resembles a three-dimensional spider web shape called the cosmic web. The filaments of the cosmic web intersect at the nodes, which equate to the galaxy shipyards in the analogy.

"We believe that the filaments mediate the transfer of hydrogen gas from the diffuse medium of intergalactic space onto these hungry, newly forming protocluster structures in the nodes," Frye said.

Pointing to future research, Polletta said: "We are in the process of analyzing more observations on this and other Planck protoclusters with the goal of tracing the gas that gives birth to these newly forming stars and feeds the supermassive black holes, to determine its origin and explain the observed extraordinary activity."

Frye said she is looking forward to combining data from the Large Binocular Telescope with observations from NASA's the James Webb Space Telescope, to be launched in December.

Read more at Science Daily

Heatwaves like ‘the Blob' could decrease role of ocean as carbon sink

Researchers have found the two-year heatwave known as 'the Blob' may have temporarily dampened the Pacific's 'biological pump,' which shuttles carbon from the surface ocean to the deep sea where it can be stored for millennia.

Canadian and European researchers, in collaboration with the U.S. Department of Energy Joint Genome Institute, conducted a large-scale study of the impact of one of the largest marine heatwaves on record -- colloquially known as the Blob -- on Pacific Ocean microorganisms. Their observations suggest that it's not just larger marine life that is affected by abrupt changes in sea temperature.

"Heatwaves such as the Blob may decrease the ocean's biological role as a carbon sink for fixed atmospheric carbon," said Dr. Steven Hallam (he/him), a microbiologist at the University of British Columbia and author of the paper published in Nature Communications Biology.

This 'biological pump' process is an important mechanism for buffering the impact of human activity on Earth's climate, said co-author Dr. Colleen Kellogg (she/her), a research scientist with the Hakai Institute. "The ocean is a huge global reservoir for atmospheric carbon dioxide. If marine heatwaves reduce the capacity for carbon dioxide to be absorbed into the ocean, then this shrinks this reservoir and leaves more of this greenhouse gas in the atmosphere."

Microbes form the base of the marine food web, performing critical functions such as synthesizing and recycling organic matter. Very little is known about how these invisible community members are affected by marine heatwaves, but understanding their responses can provide a vital sign for the rest of the marine food web.

"Marine heatwaves are one of the big challenges of climate change," explains Dr. Sachia Traving (she/her), lead author on the study at the University of Southern Denmark. "Knowing how they affect microbes -- some of the smallest but most abundant organisms on earth -- will help us understand how heatwaves will impact life in our future oceans."

To investigate these responses, the study brought together researchers from UBC, Fisheries and Oceans Canada's Institute of Ocean Sciences, and the Hakai Institute. They combined seven years of DNA sequencing and oceanographic measurements from an open-sea buoy known as Ocean Station Papa (OSP) to chart how microbial communities were structured before and during the most severe marine heatwave in recent time.

OSP is the terminal station of the Line P transect. Running continuously since 1956, Line P is one of the longest running oceanographic time series in the world, and is composed of 26 hydrographic stations originating in the coastal waters of British Columbia and heading westward to OSP, over 1,400 km from the coast.

A major impact researchers observed during the Blob, which began in 2013, was a rise in microbes specialized to survive under more nutrient limiting conditions. That shift was likely a response to changes in the composition of the region's phytoplankton, which saw a decline in larger cells that contribute to the formation of organic matter particles. That decrease in large particles in turn hinders the ocean's biological pump and ability to act as a carbon sink.

Research has shown that marine heatwaves are a direct consequence of climate change. These anomalous warm water bodies are occurring with increasing frequency as global temperatures rise, and disrupt the ecosystems in which they appear. Previous work on the Blob has documented its extensive impacts on life in the Northeastern Pacific Ocean, from phytoplankton, zooplankton and fish populations to marine mammals and birds.

Read more at Science Daily