Category: Environment

{Despite reported differences in appearance and behavior, DNA evidence finds that Namibian desert elephants share the same DNA as African savanna elephants. However, Namibian desert-dwelling elephants should be protected so they can continue to pass on their unique knowledge and survival skills to future generations.}

Despite reported differences in appearance and behavior, DNA evidence finds that Namibian desert elephants share the same DNA as African savanna elephants. However, Namibian desert-dwelling elephants should be protected so they can continue to pass on their unique knowledge and survival skills to future generations.

“The ability of species such as elephants to learn and change their behavior means that genetic changes are not critical for them to adapt to a new environment,” said lead author Alfred Roca, a professor of animal sciences and member of the Carl R. Woese Institute for Genomic Biology at the University of Illinois. “The behavioral changes can allow species to expand their range to novel marginal habitats that differ sharply from the core habitat.”

Namibian desert-dwelling elephants have figured out how to prevent overheating in triple-digit temperatures by covering their bodies with sand wetted by their urine or regurgitated water from a specialized pouch beneath their tongue that holds many gallons of water. They also remember the location of scarce water and food resources across their home ranges, which are unusually large compared to those of other elephants. They play a critical role in this arid ecosystem by creating paths and digging watering holes.

Published in Ecology and Evolution, this study evaluated the nuclear DNA and mitochondrial DNA (mtDNA) of both desert-dwelling and non-desert-dwelling elephant populations throughout Namibia. Researchers found the desert-dwelling elephant DNA was not significantly different from the DNA of other savanna elephant populations in Namibia, except from those of the Caprivi Strip.

Female elephants live in tight-knit matrilineal family groups so mutations in mtDNA, which is passed from mothers to offspring, are closely tied to geographic populations. Not surprisingly, mitochondrial DNA from savanna elephants in Namibia’s Caprivi Strip — a small region analogous to Oklahoma’s panhandle — was more similar to mitochondrial DNA of elephants in Botswana and Zimbabwe, which border the Caprivi Strip.

“Our results and the historical record suggest that a high learning capacity and long distance migrations enabled Namibian elephants to shift their ranges to survive against high variability in climate and in hunting pressure,” said first author Yasuko Ishida, a research scientist in animal sciences at Illinois.

The lack of genetic differentiation (aside from the Caprivi Strip) is consistent with historical evidence of elephant movements during the Namibian War of Independence, which increased hunting pressures. Using mtDNA, the researchers identified other Namibian elephant migration patterns; for example, elephants from the Ugab River catchment shared mtDNA with elephants from the Huab River catchment, from where they are said to have migrated.

The lack of genetic differences in Namibian elephants could also be attributed to their long distance migrations; large home ranges; recent increases in population size and range; or gene flow provided by male elephants breeding with different groups of female elephants.

“Regardless, these elephants should be conserved,” said Roca. “Their knowledge of how to live in the desert is crucial to the survival of future generations of elephants in the arid habitat, and pressure from hunting and climate change may only increase in the coming decades.

“The desert elephants are also rumored to be larger, which may put them at greater risk for trophy game hunting,” he added. “Animals that live in these marginal environments are vulnerable, and their numbers do not bounce back very quickly. ”

{For the first time, researchers have discovered that birds can sleep in flight. They measured the brain activity of frigatebirds and found that they sleep in flight with either one cerebral hemisphere at a time or both hemispheres simultaneously. Despite being able to engage in all types of sleep in flight, the birds slept less than an hour a day, a mere fraction of the time spent sleeping on land. How frigatebirds are able to perform adaptively on such little sleep remains a mystery.}

For the first time, researchers have discovered that birds can sleep in flight. Together with an international team of colleagues, Niels Rattenborg from the Max Planck Institute for Ornithology in Seewiesen measured the brain activity of frigatebirds and found that they sleep in flight with either one cerebral hemisphere at a time or both hemispheres simultaneously. Despite being able to engage in all types of sleep in flight, the birds slept less than an hour a day, a mere fraction of the time spent sleeping on land. How frigatebirds are able to perform adaptively on such little sleep remains a mystery.

It is known that some swifts, songbirds, sandpipers, and seabirds fly non-stop for several days, weeks, or months as they traverse the globe. Given the adverse effect sleep loss has on performance, it is commonly assumed that these birds must fulfill their daily need for sleep on the wing.

{{Half-awake or fully awake in flight?}}

How might a bird sleep in flight without colliding with obstacles or falling from the sky? One solution would be to only switch off half of the brain at a time, as Rattenborg showed in mallard ducks sleeping in a dangerous situation on land. When sleeping at the edge of a group, mallards keep one cerebral hemisphere awake and the corresponding eye open and directed away from the other birds, toward a potential threat. Based on these findings and the fact that dolphins can swim while sleeping unihemispherically, it is commonly assumed that birds also rely on this sort of autopilot to navigate and maintain aerodynamic control during flight.

However, it is also possible that birds evolved a way to cheat on sleep. The sleep researcher’s and colleagues’ recent discovery that male pectoral sandpipers competing for females can perform adaptively for several weeks despite sleeping very little raised the possibility that birds simply forgo sleep altogether in flight. Consequently, evidence of continuous flight is not by default evidence of sleep in flight: Without directly measuring a bird’s brain state, previous claims that birds sleep in flight remain mere speculation.

{{Flight data recorder catches birds napping on the wing}}

To actually determine whether and how birds sleep in flight, the researchers needed to record the changes in brain activity and behavior that distinguish wakefulness from the two types of sleep found in birds: slow wave sleep (SWS) and rapid eye movement (REM) sleep. Niels Rattenborg teamed up with Alexei Vyssotski (University of Zurich and Swiss Federal Institute of Technology, ETH) who developed a small device to measure electroencephalographic changes in brain activity and head movements in flying birds.

In collaboration with the Galápagos National Park and Sebastian Cruz, an Ecuadorian seabird biologist, the team focused on great frigatebirds nesting on the Galápagos Island. Frigatebirds are large seabirds that spend weeks flying non-stop over the ocean in search of flying fish and squid driven to the surface by predatory fish and cetaceans. The researchers temporarily attached the small “flight data recorder” to the head of nesting female frigatebirds. The birds then carried the recorder during non-stop foraging flights lasting up to ten days and 3000 kilometers. During this time, the recorder registered the EEG activity of both brain hemispheres and movements of the head, while a GPS device on the birds’ back tracked their position and altitude. After the birds were back on land and had had some time to recover, they were re-caught and the equipment was removed. Bryson Voirin, a post-doc and co-first author on the paper with Rattenborg observed that, “Like many other animals in the Galápagos Islands, the frigatebirds were remarkably calm and would even sleep as I approached to catch them for the second time.”

The flight data recorder revealed that frigatebirds sleep in both expected and unexpected ways during flight. During the day the birds stayed awake actively searching for foraging opportunities. As the sun set, the awake EEG pattern switched to a SWS pattern for periods lasting up to several minutes while the birds were soaring. Surprisingly, SWS could occur in one hemisphere at a time or both hemispheres together. The presence of such bihemispheric sleep indicates that unihemispheric sleep is not required to maintain aerodynamic control. Nonetheless, when compared to sleep on land, SWS was more often unihemispheric in flight. By carefully examining the movements of the frigatebirds, the researchers discovered clues to why they sleep unihemispherically in flight. When the birds circled on rising air currents the hemisphere connected to the eye facing the direction of the turn was typically awake while the other was asleep, suggesting that the birds were watching where they were going. “The frigatebirds may be keeping an eye out for other birds to prevent collisions much like ducks keep an eye out for predators,” says Rattenborg.

In addition to engaging in both types of SWS in flight, on rare occasions, bouts of SWS were interrupted by brief episodes of REM sleep. Although this finding may seem remarkable to scientists who study sleep in mammals, based on Rattenborg’s experience with birds, he was not that surprised. In contrast to mammals, wherein episodes of REM sleep are long and accompanied by a complete loss of muscle tone, REM sleep episodes only last several seconds in birds. In addition, although a reduction in muscle tone can cause the head to drop during avian REM sleep, birds are able to stand (even on one leg) during this state. Similarly, when frigatebirds entered REM sleep their head dropped momentarily, but their flight pattern remained unchanged.

{{Ecological demands require full attention 24/7 at sea}}

Perhaps the greatest surprise was that despite being able to engage in all types of sleep on the wing, on average frigatebirds slept only 42 minutes per day. In contrast, when back on land they slept for over twelve hours per day. In addition, episodes of sleep were longer and deeper on land. Collectively, this suggests that frigatebirds are actually sleep deprived in flight. “Why they sleep so little in flight, even at night when they rarely forage, remains unclear,” says Rattenborg. As previous studies have shown that frigatebirds follow ocean eddies predictive of good foraging conditions throughout the day and night, perhaps this is what they are up to. Interestingly, the low amount of sleep in flight suggests that this task requires more attention than that afforded by sleeping with one half of the brain at a time. As such, frigatebirds face ecological demands for full attention 24/7 while at sea.

In the long term, Rattenborg hopes to determine how frigatebirds are able to sustain adaptive performance on such little sleep. People will fall asleep driving a car after losing just a few hours of sleep, even when fully aware of the dangers and struggling to keep themselves awake. “Why we, and many other animals, suffer dramatically from sleep loss whereas some birds are able to perform adaptively on far less sleep remains a mystery,” notes Rattenborg. Reconciling the findings from frigatebirds with the wealth of evidence underscoring the importance of sleep in other animals may provide new perspectives on our understanding of sleep and the consequences of its loss.

{How can we ever know what ancient animals ate? For the first time, the changing diets of elephants in the last two million years in China have been reconstructed, using a technique based on analysis of the surface textures of their teeth.}

How can we ever know what ancient animals ate? For the first time, the changing diets of elephants in the last two million years in China have been reconstructed, using a technique based on analysis of the surface textures of their teeth.

The work was carried out by a University of Bristol student, working with an international team of researchers. The research was published online in Quaternary International.

Today, elephants live only in remote, tropical parts of Africa and southern Asia, but before the Ice Ages they were widespread.

As his undergraduate research project, Zhang Hanwen, MSci Palaeontology and Evolution graduate and now PhD student at the University of Bristol, undertook cutting-edge analysis of fossilised elephant teeth from China.

In a collaboration with the University of Leicester, and the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, where the fossilised teeth are curated, Hanwen sampled 27 teeth for tiny wear patterns called microwear.

“We are talking huge, brick-sized molars here — the largest of any animal,” said Hanwen, “but the signs of tooth wear are tiny, down to thousandths of a millimetre. However, these microscopic surface textures can tell us whether they were eating grass or leaves.”

Hanwen took peels of the fossilised teeth in China, using high-grade dental moulding materials, and captured the 3D surface textures under a digital microscope at the University of Leicester. The textures were quantified and analysed to identify what the elephants were eating in the days and weeks before they died.

By comparing the results with information from modern ruminants (deer, antelopes and oxen) of known diet, the study concluded two extinct elephants from Southern China — Sinomastodon and Stegodon — were primarily browsing on leaves. The third, Elephas, which includes the modern Asian elephants, shows much more catholic feeding habit, incorporating both grazing and browsing.

“It’s wonderful that we can identify diets of any fossil mammal with confidence now,” said Professor Christine Janis, from the University of Bristol, one of Hanwen’s PhD supervisors and a leading expert on the evolution of herbivorous mammals.

“This is based on the fact that the microwear textures produced by different kinds of plant material are comparable across unrelated animals.”

“This method for identifying diet relies on high-quality 3D surface data and analysis,” said Professor Mark Purnell, of the University of Leicester, another co-supervisor of Hanwen’s.

“It removes the subjectivity of trying to quantify microwear textures by identifying and counting scratches and pits in 2D microscopic images.”

Sinomastodon and Stegodon coexisted in Southern China between 2.6 and one million years ago, but Sinomastodon then became extinct and left Stegodon to become the dominant elephant of Southern China for the remainder of the Pleistocene, the time of the great Ice Ages.

“The fossil pollen record, and recently-excavated mammal fossil assemblages from various karst cave sites near the Chinese-Vietnamese border, suggest a prolonged, fluctuating period of environmental deterioration around this time,” Hanwen explained.

He added: “Forests were on the decline, alongside many of the more archaic mammal species that inhabited them. The highly evolved molars of Stegodon, with multiple enamel ridges, might have allowed it to browse on its preferred foliage in a more efficient way, thus outcompeting Sinomastodon, which preferred the same diet, but had less sophisticated molars consisting of large, blunt, conical cusps.”

On the other hand, the new study also suggests that Stegodon and Elephas subsequently coexisted for long periods in Southern China by eating different things. Stegodon remained a specialist foliage feeder whereas Elephas was more of a generalist, consuming a wider variety of vegetation.

Stegodon became extinct at around 11,000 years ago, at the end of the Pleistocene, coinciding with the worldwide disappearance of large mammal species at this time, including the iconic woolly mammoths, giant deers and sabretoothed cats. The Asian elephant survived in Southern China into historical times.

{Mathematical models offer clues to greater efficiency for glider pilots.}

Biologists and physicists have demonstrated with mathematical models how glider pilots might be able to soar more efficiently by adopting the learning strategies that birds use to navigate their way through thermals.

Migratory birds often use warm, rising atmospheric currents to gain height with little energy expenditure when flying over long distances.

It’s a behavior known as thermal soaring that requires complex decision-making within the turbulent environment of a rising column of warm air from the sun baked surface of the earth.

But exactly how birds navigate within this ever-changing environment to optimize their thermal soaring was unknown until a team of physicists and biologists at the University of California San Diego took an exacting computational look at the problem.

In this week’s online version of the journal Proceedings of the National Academy of Sciences, the scientists demonstrated with mathematical models how glider pilots might be able to soar more efficiently by adopting the learning strategies that birds use to navigate their way through thermals.

“Relatively little is known about the navigation strategies used by birds to cope with these challenging conditions, mainly because past computational research examined soaring in unrealistically simplified situations,” explained Massimo Vergassola, a professor of physics at UC San Diego.

To tackle the problem, he and his colleagues, including Terrence Sejnowski, a professor of neurobiology at the Salk Institute and UC San Diego, combined numerical simulations of atmospheric flow with “reinforcement learning algorithms” — equations originally developed to model the behavior and improved performance of animals learning a new task. Those algorithms were developed in a manner that trained a glider to navigate complex turbulent environments based on feedback on the glider’s soaring performance.

According to Sejnowski, the “reinforcement learning architecture” was the same as that used by Google’s DeepMind AlphaGo program, which made headlines in 2016 after beating the human professional Go player Lee Sedol.

When applying it to soaring performance, the researchers took into account the bank angle and the angle of attack of the glider’s wings as well as how the temperature variations within the thermal impacted vertical velocity.

“By sensing two environmental cues — vertical wind acceleration and torque — the glider is able to climb and stay within the thermal core, where the lift is typically the largest, resulting in improved soaring performance, even in the presence of strong turbulent fluctuations,” said Vergassola. “As turbulent levels rise, the glider can avoid losing height by adopting increasingly conservative, risk-averse flight strategies, such as continuing along the same path rather than turning.”

In the two, three dimensional color graphs (shown above), the scientists illustrate how an untrained glider (at left) takes random decisions and descends, while the trained glider (at right) learns to employ the characteristic spiraling patterns in regions of strong ascending currents, as observed in the thermal soaring of birds and gliders. (The colors indicate the vertical wind velocity experienced by the glider. The green and red dots indicate the start and the end points of the trajectory, respectively.)

The researchers write in their paper that, based on their study, “torque and vertical accelerations” appear to be the sensorimotor cues that most effectively guide the most efficient soaring path of birds through thermals, rather than differences in temperature.

“Temperature was specifically shown to yield minor gains,” they write adding that “a sensor of temperature could then be safely spared in the instrumentation for autonomous flying vehicles.”

“Our findings shed light on the decision-making processes that birds might use to successfully navigate thermals in turbulent environments,” said Vergassola. “This information could guide the design of simple mechanical instrumentation that would allow autonomous gliders to travel long distances with minimal energy consumption.”

“The high levels of soaring performance demonstrated in simulated turbulence could lead to the development of energy efficient autonomous gliders,” said Sejnowski, who is also a Howard Hughes Medical Institute Investigator.

Other members of the research team were Gautam Reddy, a physicist at UC San Diego and the first author of the paper, and Antonio Celani of the Abdus Salam International Center for Theoretical Physics in Trieste, Italy. The study was supported by a grant from the Simons Foundation.

{Newly discovered fossil evidence from Namibia strengthens the proposition that the world’s first mass extinction was caused by ‘ecosystem engineers’ — newly evolved biological organisms that altered the environment so radically it drove older species to extinction.}

The event, known as the end-Ediacaran extinction, took place 540 million years ago.

The earliest life on Earth consisted of microbes — various types of single-celled organisms. These held sway for more than 3 billion years, when the first multicellular organisms evolved. The most successful of these were the Ediacarans, which spread around the globe about 600 million years ago. They were a largely immobile form of marine life shaped like discs and tubes, fronds and quilted mattresses.

After 60 million years, evolution gave birth to another major innovation: metazoans, the first animals. Metazoans could move spontaneously and independently at least during some point in their life cycle and sustain themselves by eating other organisms or what other organisms produce. Animals burst onto the scene in a frenzy of diversification that paleontologists have labeled the Cambrian explosion, a 25 million-year period when most of the modern animal families — vertebrates, mollusks, arthropods, annelids, sponges and jellyfish — came into being.

“These new species were ‘ecological engineers’ who changed the environment in ways that made it more and more difficult for the Ediacarans to survive,” said Simon Darroch, assistant professor of earth and environmental sciences at Vanderbilt University, who directed the new study described in the paper titled “A mixed Ediacaran-metazoan assemblage from the Zaris Sub-basin, Namibia,” published in the journal Palaeogeography, Palaeoclimatology, Palaeoecology.

Darroch and his colleagues report that they have found one of the best-preserved examples of a mixed community of Ediacarans and animals, which provides the best evidence of a close ecological association between the two groups.

“Until this, the evidence for an overlapping ecological association between metazoans and soft-bodied Ediacaran organisms was limited,” Darroch said. “Here, we describe new fossil localities from southern Namibia that preserve soft-bodied Ediacara biota, enigmatic tubular organisms thought to represent metazoans and vertically oriented metazoan trace fossils. Although the precise identity of the tracemakers remains elusive, the structures bear several striking similarities with a cone-shaped organism called Conichnus that has been found in the Cambrian period.”

In a previous paper that Darroch and his collaborators published last September, they reported on a fossil record that showed stressed-looking communities of Ediacara associated with a suite of animal burrows.

“With this paper we’re narrowing in on causation; we’ve discovered some new fossil sites that preserve both Ediacara biota and animal fossils (both animal burrows — ‘trace fossils’ — and the remains of animals themselves) sharing the same communities, which lets us speculate about how these two very different groups of organisms interacted,” he said.

“Some of the burrow fossils we’ve found are usually interpreted as being formed by sea anemones, which are passive predators that may have preyed upon Ediacaran larvae. We’ve also found stands of Ediacaran frondose organisms, with animal fossils preserved in place coiled around their bases. In general, these new fossil sites reveal a snapshot of a very unusual ‘transitional’ ecosystem existing right before the Cambrian explosion, with the last of the Ediacara biota clinging on for grim death, just as modern-looking animals are diversifying and starting to realize their potential.”

Although Darroch is studying events that took place 540 million years ago, he believes there is a message relevant for today. “There is a powerful analogy between Earth’s first mass extinction and what is happening today,” he said. “The end-Ediacaran extinction shows that the evolution of new behaviors can fundamentally change the entire planet, and today we humans are the most powerful ‘ecosystems engineers’ ever known.”

{Honey bees are able to wiggle their abdomens in a variety of ways. Now new research shows how they are able to do it. Specialized membranes that connect a honey bee’s abdominal segments are thicker on the top of the abdomen than on the bottom, report the scientists.This asymmetry allows the segments to lengthen on top and contract on the bottom, resulting in the unidirectional curling the researchers observed in the bees they filmed.}

Honey bees are able to wiggle their abdomens in a variety of ways. Now new research published in the Journal of Insect Science shows how they are able to do it.

In 2015, a team of researchers from Tsinghua University in Beijing used a high-speed camera to observe how honey bees curl their abdomens while in flight and under restraint, confirming that bees can manipulate the shape of their abdomens, but only in one direction — down, toward the bee’s underside.

Now the same team has identified the mechanism behind that movement. Specialized membranes that connect a honey bee’s abdominal segments are thicker on the top of the abdomen than on the bottom, allowing curling in just one direction.

Honey bee abdomens contain up to nine overlapping segments that are similar to little armored plates. A thin, flexible layer of cells called the folded intersegmental membrane (FIM) connects the tough outer plates, allowing each concentric segment not just to attach to its neighbor, but to slide into the next one. The authors call this movement “telescoping.”

“Our research on the ultrastructure of the FIM is of great significance to reveal the bending and flexing motion mechanism of the honey bee abdomen,” said Professor Shaoze Yan, one of the co-authors. “During nectar feeding, a honey bee’s abdomen does high-frequency respiratory exercises and assists the suction behavior of mouthparts to improve the intake efficiency.”

In this experiment, the researchers looked at forager honey bees using the same combination of high-speed videography and scanning electron microscopy as they did in 2015. The engineers recorded the abdominal wiggling of live honey bees and the internal shapes of dissected bee abdomens.The flying videos were shot at 500 frames per second, and the dissected abdomens were imaged in thin slices.

The microscopy showed that the membranes along the top of the honey bee’s abdomen are two times thicker than those on the bottom.This asymmetry allows the segments to lengthen on top and contract on the bottom, resulting in the unidirectional curling the researchers observed in the bees they filmed.

It’s a design that the paper’s authors suggest is ripe for exploration by more engineers, perhaps for use in aircraft design or other applications.

{A new species of extinct flesh-eating marsupial that terrorized Australia’s drying forests about 5 million years ago has been identified from a fossil discovered in remote northwestern Queensland. The hypercarnivore is a distant and much bigger cousin of Australia’s largest living, flesh-eating marsupial, the Tasmanian devil. Named Whollydooleya tomnpatrichorum, it is the first creature to be formally identified from a range of strange new animals whose remains have been found in a recently discovered fossil site in Queensland dubbed ‘New Riversleigh.’}

A new species of extinct flesh-eating marsupial that terrorised Australia’s drying forests about 5 million years ago has been identified from a fossil discovered in remote northwestern Queensland.

The hypercarnivore, which is thought to have weighed about 20 to 25 kilograms, is a distant and much bigger cousin of Australia’s largest living, flesh-eating marsupial, the Tasmanian Devil, which weighs in at about 10 kilogram.

Named Whollydooleya tomnpatrichorum, it is the first creature to be formally identified from a range of strange new animals whose remains have been found in a recently discovered fossil site in Queensland dubbed ‘New Riversleigh’.

A description of the new marsupial, based on its fossil molar tooth, is published in the Memoirs of Museum Victoria.

“W. tomnpatrichorum had very powerful teeth capable of killing and slicing up the largest animals of its day,” says study lead author UNSW Professor Mike Archer.

The late Miocene period between about 12 and 5 million years ago, when Australia began to dry out and the megafauna began to evolve, is one of the most mysterious and least well-understood periods in the continent’s past. Fossils of land animals from this period are extremely rare, because of the increasing aridity.

“Fortunately, in 2012, we discovered a whole new fossil field that lies beyond the internationally famous Riversleigh World Heritage Area fossil deposits in north-western Queensland,” says Professor Archer.

“This exciting new area – New Riversleigh – was detected by remote sensing using satellite data.”

With the help of ARC funding and a grant from the National Geographic Society, Professor Archer and his colleagues began to systematically explore New Riversleigh in 2013.

The new species’ highly distinctive molar was one of the first fossil teeth obtained from a particularly fossil-rich site in the area which was discovered by team member Phil Creaser and named Whollydooley Hill in honour of his partner and Riversleigh volunteer Genevieve Dooley.

“New Riversleigh is producing the remains of a bevy of strange new small to medium-sized creatures, with Whollydooleya tomnpatrichorum, the first one to be described,” says Professor Archer.

“These new discoveries are starting to fill in a large hole in our understanding about how Australia’s land animals transformed from being small denizens of its ancient wet forests to huge survivors on the second most arid continent on Earth.”

Team member UNSW Professor Suzanne Hand says medium to large-sized Australian Late Miocene animals have previously been known from fossil deposits in the Northern Territory, such as at Alcoota.

“But those deposits give almost no information about the small to medium-sized mammals that existed at the same time, which generally provide more clues about the nature of prehistoric environments and climates,” Professor Hand says.

Team member and UNSW postdoctoral researcher in palaeontology, Dr Karen Black, adds: “The small to medium-size mammals from the New Riversleigh deposits will reveal a great deal about how Australia’s inland environments and animals changed between 12 and 5 million years ago – a critical time when increasing dryness ultimately led to the Ice Ages of the Pleistocene.”

The Whollydooley Site deposit provides other exciting clues about how the environment was changing. For example, it contains the first signs of wind-blown sand grains, which are absent from the older Riversleigh World Heritage deposits.

And the teeth of the other animals in this deposit are unusual for Riversleigh, because they are more worn down. This suggests that the foods animals were eating in the late Miocene were perhaps tougher, more drought-resistant plants, and there was more abrasive dust in the environment.

“Although Whollydooleya terrorized the drying forests around 5 million years ago, its own days were numbered,” says Archer.

“While it was at least distantly related to living and recently living carnivorous marsupials such as Devils, Thylacines and Quolls, it appears to have represented a distinctive subgroup of hypercarnivores that did not survive into the modern world.

“Climate change can be a merciless eliminator of the mightiest of mammals,” he says.

{New findings suggest that the famous cooperation between honeyguide birds and human honey hunters in sub-Saharan Africa is a two-way conversation.}

Honeyguides fly ahead of hunters and point out beehives which the hunters raid, leaving wax for the birds to eat.

The birds were already known to chirp at potential human hunting partners.
Now, a study in the journal Science reports that they are also listening out for a specific call made by their human collaborators.

Experiments conducted in the savannah of Mozambique showed that a successful bird-assisted hunt was much more likely in the presence of a distinctive, trilling shout that the Yao hunters of this region learn from their fathers.

“They told us that the reason they make this ‘brrrr-hm’ sound, when they’re walking through the bush looking for bees’ nests, is that it’s the best way of attracting a honeyguide – and of maintaining a honeyguide’s attention once it starts guiding you,” said Dr Claire Spottiswoode, a researcher at the University of Cambridge, UK, and the University of Cape Town, South Africa, who led the study.

She and her colleagues wanted to test what contribution this sound actually made.

“In particular, we wanted to distinguish whether honeyguides responded to the specific information content of the ‘brrr-hm’ call – which, from a honeyguide’s point of view, effectively signals ‘I’m looking for bees’ nests’ – or whether the call simply alerts honeyguides to the presence of humans in the environment.”

To make that distinction, the team made recordings of the “brrrr-hm” call, as well as of general human vocal sounds such as the hunters shouting their own names, or the Yao word for “honey”.

Then, Dr Spottiswoode accompanied two Yao honey hunters on 72 separate 15-minute walks through the Niassa National Reserve – a protected area the size of Denmark – playing these recordings on a speaker.

“This was great fun,” she told BBC News. “We walked hundreds of kilometres through beautiful landscapes and occasionally bumped into elephants and buffalo and lions and so on. It’s a really remarkable wilderness where humans and wildlife still coexist.”

Sure enough, walks accompanied by the “brrrr-hm” recordings were much more likely to recruit a honeyguide (66% of the time, compared to 25% for the other vocal sounds).
The special call also trebled the overall chance of finding a beehive (a 54% success rate, up from 17% for the other sounds).

“What this suggests is that honeyguides are attaching meaning, and responding appropriately, to the signal that advertises people’s willingness to cooperate.

“We already knew very well… that honeyguides communicate with humans, using special calls and behaviour to lead honey hunters to bees’ nests. What our work has done is to complement those findings, by showing that humans communicate back to honeyguides too.

“It seems to be a two-way conversation between our own species and a wild animal, from which both partners benefit.”

Prof Richard Wrangham, a biological anthropologist at Harvard University, said the new study greatly strengthened the idea that honeyguides had evolved to cooperate with humans in this way.

He said a previous explanation, that the teamwork originated with another species – such as honey badgers or baboons – and was then co-opted by humans, had fallen from favour because the birds had never been witnessed guiding these animals.

“[This study] shows just how tightly attuned they are to human sounds,” Prof Wrangham told the BBC. “They’re not just generally interested in weird noises – anything loud or unusual or whatever.They have been trained, as it were, to look for humans.

“That really supports the notion that this is an evolved, co-evolutionary relationship.”

{Female bonobo coalitions more easily defeat aggressive males.}

Bullying happens in the primate world too, but for young bonobo females, big mama comes to the rescue. Japanese primatologists report in Animal Behaviour that older bonobo females frequently aid younger females when males behave aggressively towards them.

“We may have uncovered one of the ways in which females maintain a superior status in bonobo society,” says lead author Nahoko Tokuyama of Kyoto University.

In their study, Tokuyama and fellow researcher Takeshi Furuichi observed a group of wild bonobos at Wamba, Democratic Republic of the Congo.

“Primate females sometimes forge partnerships to attack others. Typically, such coalitions are formed between relatives to protect useful resources from non-relatives.” says Tokuyama. “For bonobos, females leave their birth group during adolescence, so females in a group are generally non-relative to each other. Despite this, they frequently form coalitions; a major research goal for us was to highlight the dynamics in which coalition-forming happens in non-relative individuals.”

Through four years of observation they found that all female coalitions were formed to attack males, usually after males behaved aggressively toward one or more females. They also found that older females have better chances of winning when the battle is one-one-one, and when females form alliances they always win over males. What’s more, the older females don’t play favorites; whether a younger female is friendlier with the older female has no relation to whether the older female comes to help.

Tokuyama observes that coalition-forming in female bonobos may have evolved as a way to combat male harassment. “Young females have a lower social status than males, but protection from older females seem to let young females join the group without fear of being attacked by males. By controlling aggression by males in this manner, females maintain overall superiority in the social hierarchy.

“It’s beneficial for the older females as well, because the younger females start spending more time with them in hopes of getting protection.This way, the older female can give her son more opportunities to mate with the younger females. Such partnerships might in fact be the very factor that fosters gregariousness and promotes tolerance among females.”

{Two key climate change indicators — global surface temperatures and Arctic sea ice extent — have broken numerous records through the first half of 2016, according to NASA analyses of ground-based observations and satellite data.}

Each of the first six months of 2016 set a record as the warmest respective month globally in the modern temperature record, which dates to 1880, according to scientists at NASA’s Goddard Institute for Space Studies (GISS) in New York. The six-month period from January to June was also the planet’s warmest half-year on record, with an average temperature 1.3 degrees Celsius (2.4 degrees Fahrenheit) warmer than the late nineteenth century.

Five of the first six months of 2016 also set records for the smallest respective monthly Arctic sea ice extent since consistent satellite records began in 1979, according to analyses developed by scientists at NASA’s Goddard Space Flight Center, in Greenbelt, Maryland. The one exception, March, recorded the second smallest extent for that month.

While these two key climate indicators have broken records in 2016, NASA scientists said it is more significant that global temperature and Arctic sea ice are continuing their decades-long trends of change. Both trends are ultimately driven by rising concentrations of heat-trapping carbon dioxide and other greenhouse gases in the atmosphere.

The extent of Arctic sea ice at the peak of the summer melt season now typically covers 40 percent less area than it did in the late 1970s and early 1980s. Arctic sea ice extent in September, the seasonal low point in the annual cycle, has been declining at a rate of 13.4 percent per decade.

“While the El Niño event in the tropical Pacific this winter gave a boost to global temperatures from October onwards, it is the underlying trend which is producing these record numbers,” GISS Director Gavin Schmidt said.

Previous El Niño events have driven temperatures to what were then record levels, such as in 1998. But in 2016, even as the effects of the recent El Niño taper off, global temperatures have risen well beyond those of 18 years ago because of the overall warming that has taken place in that time.

The global trend in rising temperatures is outpaced by the regional warming in the Arctic, said Walt Meier, a sea ice scientist at NASA Goddard.

“It has been a record year so far for global temperatures, but the record high temperatures in the Arctic over the past six months have been even more extreme,” Meier said. “This warmth as well as unusual weather patterns have led to the record low sea ice extents so far this year.”

NASA tracks temperature and sea ice as part of its effort to understand the Earth as a system and to understand how Earth is changing. In addition to maintaining 19 Earth-observing space missions, NASA also sends researchers around the globe to investigate different facets of the planet at closer range. Right now, NASA researchers are working across the Arctic to better understand both the processes driving increased sea ice melt and the impacts of rising temperatures on Arctic ecosystems.

NASA’s long-running Operation IceBridge campaign last week began a series of airborne measurements of melt ponds on the surface of the Arctic sea ice cap. Melt ponds are shallow pools of water that form as ice melts. Their darker surface can absorb more sunlight and accelerate the melting process. IceBridge is flying out of Barrow, Alaska, during sea ice melt season to capture melt pond observations at a scale never before achieved. Recent studies have found that the formation of melt ponds early in the summer is a good predictor of the yearly minimum sea ice extent in September.

“No one has ever, from a remote sensing standpoint, mapped the large-scale depth of melt ponds on sea ice,” said Nathan Kurtz, IceBridge’s project scientist and a sea ice researcher at NASA Goddard. “The information we’ll collect is going to show how much water is retained in melt ponds and what kind of topography is needed on the sea ice to constrain them, which will help improve melt pond models.”

Operation IceBridge is a NASA airborne mission that has been flying multiple campaigns at both poles each year since 2009, with a goal of maintaining critical continuity of observations of sea ice and the ice sheets of Greenland and Antarctica.

At the same time, NASA researchers began in earnest this year a nearly decade-long, multi-faceted field study of Arctic ecosystems in Alaska and Canada.The Arctic-Boreal Vulnerability Experiment (ABoVE) will study how forests, permafrost and other ecosystems are responding to rising temperatures in the Arctic, where climate change is unfolding faster than anywhere else on the planet.

ABoVE consists of dozens individual experiments that over years will study the region’s changing forests, the cycle of carbon movement between the atmosphere and land, thawing permafrost, the relationship between fire and climate change, and more.