Category: Science News

{Fossil remains of a previously unknown family of carnivorous Australian marsupials that lived 15 million years ago have been discovered at the Riversleigh World Heritage Fossil Site in north-western Queensland by a UNSW Australia-led team of researchers.}

“Malleodectes mirabilis was a bizarre mammal, as strange in its own way as a koala or kangaroo,” says study lead author UNSW Professor Mike Archer.

“Uniquely among mammals, it appears to have had an insatiable appetite for escargot–snails in the whole shell. Its most striking feature was a huge, extremely powerful, hammer-like premolar that would have been able to crack and then crush the strongest snail shells in the forest.”

Research describing the new marsupials is published in the journal Scientific Reports.

Isolated teeth and partial dentitions of this unusual group, known as malleodectids, had been unearthed over the years at Riversleigh, where Professor Archer and his colleagues have excavated for almost four decades. But the profoundly different nature of the marsupials was not realised until a well-preserved portion of the skull of a juvenile was found in a 15 million year old Middle Miocene cave deposit at Riversleigh.

This juvenile specimen was only recently extracted from its limestone casing, using an acid bath at UNSW, which made it available for study with modern techniques including micro-computed tomography. The young animal still had its baby teeth, and was teething, with adult teeth that had been about to erupt when it was alive still embedded in its jaw.

“Details of the canine, premolar and molar teeth of this specimen have enabled its relationships to other Australian marsupials to be determined with reasonable confidence,” says Professor Archer, of the PANGEA Research Centre in the UNSW School of Biological, Earth and Environmental Sciences.

“Although it is very different from the others, it appears to have been related to the dasyures — marsupial carnivores such as Tasmanian Devils and the extinct Tasmanian Tigers that are unique to Australia and New Guinea.”

Nothing remains of the cave at Riversleigh, known as AL90 site, except its limestone floor, which contains the bones of thousands of animals that fell into, or lived in, the ancient cave.

“The juvenile malleodectid could have been clinging to the back of its mother while she was hunting for snails in the rocks around the cave’s entrance, and may have fallen in and then been unable to climb back out,” says team member UNSW Professor Suzanne Hand.

“Many other animals that lived in this lush forest met a similar fate with their skeletons accumulating one on top of another for perhaps thousands of years, until the cave became filled with palaeontological treasures.

“Over millions of years the walls and ceiling of the cave were eroded away, leaving only the fossil-rich floor, which was discovered by our Riversleigh Project team members in 1990.”

Subsequent quarrying of the cave floor has produced thousands of exquisite fossils including the articulated skeletons of the ram-sized, sloth-like Nimbadon — an extinct marsupial that fell in while moving overhead in the tree tops.

The Riversleigh World Heritage fossil deposits, which span the last 24 million years of Australian history, have produced many previously unknown kinds of animals such as Thingodonta, which may have been a woodpecker-like marsupial; Fangaroo, a tusked kangaroo; Drop crocs, which are strange leopard-like crocodiles that may have been arboreal; and Dromornis — the Demon Duck of Doom, which was one of the largest birds in the world.

The Riversleigh Project, which has been a major focus of the palaeontological team at UNSW, is about to carry out its 40th annual expedition to Riversleigh.

Once again, the team expects to discover yet more strange creatures that once populated Australia’s ancient rainforests at a time when the northern regions of the continent looked more like Amazonian rainforests than the arid zone the area has become today.

Of particular interest for this year’s expedition will be younger apparently Late Miocene rocks discovered by the team, assisted by funding from the Australian Research Council and the National Geographic Society, in a remote area now called “New Riversleigh.” These will fill a key time period for the rich, long record of environmental change at Riversleigh.

Among the first tantalising discoveries from “New Riversleigh” has been yet another bizarre, hyper-carnivorous marsupial that looks like it might be a younger, far more powerful cousin of the earlier snail-eating malleodectids.

Like so many of the strange creatures continuously being discovered in Riversleigh’s rocks, malleodectids went extinct long before humans arrived.

The most probable cause was a severe interval of climate change that began about 15 million years ago and ultimately transformed Australia’s once widespread, animal-rich rainforests into the more open forests and grasslands of today.

“This climate change-driven transformation in Australia’s wildlife over the last 15 million years is a timely reminder of the probable outcome of the next cycle of climate change, one we appear to have triggered ourselves,” says Professor Archer.

{The economic crisis of 2008-10, and the rise in unemployment that accompanied it, was associated with more than 260,000 excess cancer-related deaths–including many considered treatable–within the Organization for Economic Development (OECD), according to a study from Harvard T.H. Chan School of Public Health, Imperial College London, and Oxford University. The researchers found that excess cancer burden was mitigated in countries that had universal health coverage (UHC) and in those that increased public spending on health care during the study period.}

The study will be published May 25, 2016 in The Lancet.

“Higher unemployment due to economic crisis and austerity measures is associated with higher number of cancer deaths. Universal health coverage protects against these deaths. That there are needless deaths is a major societal concern,” said Rifat Atun, professor of global health systems at Harvard Chan School and senior author of the study. He added that increased joblessness during the economic crisis may have limited people’s access to health care, leading to late-stage diagnoses and poor or delayed treatment.

“Cancer is a leading cause of death worldwide so understanding how economic changes affect cancer survival is crucial,” says lead author Mahiben Maruthappu from Imperial College London, UK. “We also found that public healthcare spending was tightly associated with cancer mortality–suggesting healthcare cuts could cost lives.”

Although previous studies have shown connections between economic changes and rates of suicides, cardiovascular disease, and overall mortality, only a few had examined the relationship between economic downturns and cancer outcomes, especially in countries with underdeveloped social security and health care systems.

The researchers analyzed the link between unemployment, public health care spending, and cancer mortality using data from 1990-2010 from more than 70 high- and middle-income countries around the world, representing roughly 2 billion people. The researchers looked at deaths from several “treatable” cancers, for which survival rates exceed 50%–including breast cancer in women, prostate cancer in men, and colorectal cancers in both men and women–and from a few “untreatable” cancers (with five-year survival rates less than 5%), including lung and pancreatic cancers in men and women.

The researchers found that increases in unemployment were associated with increased mortality from all the cancer types included in the study. The association was strongest for treatable cancers, suggesting that lack of access to care may have been a factor in these excess deaths. Also, comparing estimates of expected cancer deaths with actual deaths from 2008-10, they found that the recent global economic crisis was linked with more than 260,000 excess cancer deaths among the 35 member states of the OECD alone.

Adverse health effects persisted for several years after initial increases in unemployment, the study found. In addition, excess cancer deaths were a more significant problem in middle-income countries than in high-income countries.

In countries with UHC–defined in the study as countries that have legislation mandating UHC, more than 90% health care coverage, and more than 90% skilled birth attendance–the link between unemployment and excess cancer deaths disappeared, suggesting that greater access to health care played a key role in mitigating the problem. Twenty-six OECD countries were listed in the study as having UHC, while nine–Barbados, Latvia, Lithuania, Malta, Mexico, Poland, Russia, the U.S., and Uruguay–did not have it.

Researchers also found that increases in public sector health spending helped blunt the negative health impact of unemployment increases.

One limitation of the study was that it was not a truly global analysis, given scarcity of data from China, India, and low-income countries. The study was also unable to draw any firm conclusions about causality, although the authors did note that changes in unemployment were followed by changes in cancer mortality, which does suggest a causal link.

{Neuroscience study identifies brain chemicals, neural pathway involved in switching between habitual behavior, deliberate decision-making.}

Not all habits are bad. Some are even necessary. It’s a good thing, for example, that we can find our way home on “autopilot” or wash our hands without having to ponder every step. But inability to switch from acting habitually to acting in a deliberate way can underlie addiction and obsessive compulsive disorders.

Working with a mouse model, an international team of researchers demonstrates what happens in the brain for habits to control behavior.

The study is published in Neuron and was led by Christina Gremel, assistant professor of psychology at the University of California San Diego, who began the work as a postdoctoral researcher at the National Institute on Alcohol Abuse and Alcoholism of the National Institutes of Health. Senior authors on the study are Rui Costa, of the Champalimaud Centre for the Unknown in Lisbon, and David Lovinger of the NIAAA/NIH.

The study provides the strongest evidence to date, Gremel said, that the brain’s circuits for habitual and goal-directed action compete for control — in the orbitofrontal cortex, a decision-making area of the brain — and that neurochemicals called endocannabinoids allow for habit to take over, by acting as a sort of brake on the goal-directed circuit.

Endocannabinoids are a class of chemicals produced naturally by humans and other animals. Receptors for endocannabinoids are found throughout the body and brain, and the endocannabinoid system is implicated in a variety of physiological processes — including appetite, pain sensation, mood and memory. It is also the system that mediates the psychoactive effects of cannabis.

Earlier work by Gremel and Costa had shown that the orbitofrontal cortex, or OFC, is an important brain area for relaying information on goal-directed action. They found that by increasing the output of neurons in the OFC with a technique called optogenetics — precisely turning neurons on and off with flashes of light — they increased goal-directed actions. In contrast, when they decreased activity in the same area with a chemical approach, they disrupted goal-directed actions and the mice relied on habit instead.

“Habit takes over when the OFC is quieted,” Gremel said.

In the current study, since endocannabinoids are known to reduce the activity of neurons in general, the researchers hypothesized that endocannabinoids may be quieting or reducing activity in the OFC and, with it, the ability to shift to goal-directed action. They focused particularly on neurons projecting from the OFC into the dorsomedial striatum.

They trained mice to perform the same lever-pressing action for the same food reward but in two different environments that differentially bias the development of goal-directed versus habitual actions. Like humans who don’t suffer from neuropsychiatric disorders, healthy mice will readily shift between performing the same action using a goal-directed versus habitual action strategy. To stick with the earlier example of getting home, we can switch the homing autopilot off and shift to goal-directed behavior when we need to get to a new or different location.

To test their hypothesis on the role played by endocannabinoids, the researchers then deleted a particular endocannabinoid receptor, called cannabinoid type 1, or CB1, in the OFC-to-striatum pathway. Mice missing these receptors did not form habits — showing the critical role played by the neurochemicals as well as that particular pathway.

“We need a balance between habitual and goal-directed actions. For everyday function, we need to be able to make routine actions quickly and efficiently, and habits serve this purpose,” Gremel said. “However, we also encounter changing circumstances, and need the capacity to ‘break habits’ and perform a goal-directed action based on updated information. When we can’t, there can be devastating consequences.”

The findings may suggest, the authors say, a new therapeutic target for people suffering from OCD or addictions: To stop overreliance on habit and restore the ability to shift from habit to goal-directed action, it may be helpful to treat the brain’s endocannabinoid system and so reduce habitual control over behavior. Treatment could be pharmaceutical or might involve behavioral therapy. Further research is needed.

{A study of more than 6,000 marine fossils from the Antarctic shows that the mass extinction event that killed the dinosaurs was sudden and just as deadly to life in the polar regions.}

Previously, scientists had thought that creatures living in the southernmost regions of the planet would have been in a less perilous position during the mass extinction event than those elsewhere on Earth.

The research, published today in the journal Nature Communications, involved a six-year process of identifying more than 6,000 marine fossils ranging in age from 69- to 65-million-years-old that were excavated by scientists from the University of Leeds and the British Antarctic Survey on Seymour Island in the Antarctic Peninsula.

This is one of the largest collections of marine fossils of this age anywhere in the world. It includes a wide range of species, from small snails and clams that lived on the sea floor, to large and unusual creatures that swam in the surface waters of the ocean. These include the ammonite Diplomoceras, a distant relative of modern squid and octopus, with a paperclip-shaped shell that could grow as large as 2 metres, and giant marine reptiles such as Mosasaurus, as featured in the film Jurassic World.

With the marine fossils grouped by age, the collection shows a dramatic 65-70% reduction in the number of species living in the Antarctic 66 million years ago — coinciding exactly with the time when the dinosaurs and many other groups of organisms worldwide became extinct at the end of the Cretaceous Period.

James Witts, a PhD student in the University’s School of Earth and Environment and lead author of the new research paper said: “Our research essentially shows that one day everything was fine — the Antarctic had a thriving and diverse marine community — and the next, it wasn’t. Clearly, a very sudden and catastrophic event had occurred on Earth.

“This is the strongest evidence from fossils that the main driver of this extinction event was the after-effects of a huge asteroid impact, rather than a slower decline caused by natural changes to the climate or by severe volcanism stressing global environments.”

The study is the first to suggest that the mass extinction event was just as rapid and severe in the polar regions as elsewhere in the world.

Previously, scientists had thought that organisms living near the Poles were far enough away from the cause of the extinction to be badly affected — whether this was an asteroid impact in the Gulf of Mexico, where a giant buried impact crater is found today, or extreme volcanism in the Deccan volcanic province in India. Furthermore, it had been proposed that animals and plants in the polar regions would have been more resilient to global climatic changes associated with an asteroid impact as a result of living in environments that were always strongly seasonal. For example, life near the Poles has to adapt to living in darkness for half of the year and to an irregular food supply.

Professor Jane Francis from the British Antarctic Survey, a co-author of the study, said: “These Antarctic rocks contain a truly exceptional assemblage of fossils that have yielded new and surprising information about the evolution of life 66 million years ago. Even the animals that lived at the ends of the Earth close to the South Pole were not safe from the devastating effects of the mass extinction at the end of the Cretaceous Period.”

While some previous studies have suggested that the demise of the dinosaurs and other groups was gradual, many scientists argue that the dinosaur fossil record in particular is patchy, and cannot compete with marine fossils in terms of quantity and biodiversity.

James Witts said: “Most fossils are formed in marine environments, where it is easy for sediment to accumulate rapidly and bury parts of animals, such as bones, or bodies of creatures with a hard shell. For a dinosaur or other land animal to become fossilised, a series of favourable events are needed, such as for bones to fall into stagnant water and be buried rapidly to prevent decomposition, or be washed out to sea by rivers.

“This means that marine fossils are generally much more abundant. They can give us a much larger data set for studying how ecosystems and biodiversity change over time in the geological past, and enable us to draw robust conclusions about events during periods of rapid environmental change, like mass extinctions.”

{The visible impacts of depression and stress that can be seen in a person’s face — and contribute to shorter lives — can also be found in alterations in genetic activity, according to newly published research.}

In a series of studies involving both C. elegans worms and human cohorts, researchers from the Indiana University School of Medicine and the Scripps Research Institute have identified a series of genes that may modulate the effects of good or bad mood and response to stress on lifespan. In particular, the research pointed to a gene known as ANK3 as playing a key role in affecting longevity. The research was published May 24, 2016 in the Nature Publishing Group journal Molecular Psychiatry, the top ranked journal in the field of psychiatry.

“We were looking for genes that might be at the interface between mood, stress and longevity,” said Alexander B. Niculescu III, M.D., Ph.D., professor of psychiatry and medical neuroscience at the IU School of Medicine. “We have found a series of genes involved in mood disorders and stress disorders which also seem to be involved in longevity.

“Our subsequent analyses of these genes found that they change in expression with age, and that people subject to significant stress and/or mood disorders, such as people who completed suicide, had a shift in expression levels of these genes that would be associated with premature aging and reduced longevity” said Dr. Niculescu, who is also attending psychiatrist and research and development investigator at the Indianapolis Veterans Affairs Medical Center.

The research began with studies in C. elegans, a worm widely used in life sciences research. An earlier study by one of the study co-authors, Michael Petrascheck, Ph.D., of the Scripps Research Institute, found that exposing C. elegans to the antidepressant mianserin, which is used to treat mood and stress disorders, extended the animal’s lifespan.

In the Molecular Psychiatry study, the researchers methodically conducted a series of analyses to discover, prioritize,

In C. elegans, 231 genes were identified whose activities were altered after administration of mianserin and for which there were 347 similar genes in humans.
The 347 human genes were cross-referenced with a genome analysis of data from 3,577 older adults to identify those genes that might be associated with depressive symptoms in humans, resulting in 134 genes that overlapped.

The 134 genes were prioritized for involvement in mood disorders and stress disorders, using the Niculescu lab’s Convergent Functional Genomics approach and comprehensive databases of human and animal model genetic and gene expression studies in psychiatric disorders. The top scoring gene from the list was ANK3, which in recent years has become well known as playing a role in psychiatric disorders.

Returning to the C. elegans model, the researchers tested the effects of mianserin and of oxidative stress on worms with mutated — and therefore inactive — versions of the ANK3 gene, compared to non-mutated wild-type worms. ANK3 expression increases with age in worms. Mianserin maintains lower, youthful levels of ANK3 expression, but does require some ANK3 to be present for its effects on longevity. Thus, there seems to be a “Goldilocks” effect.

Next, using more than 700 blood samples from patients diagnosed with psychiatric disorders, as well as studying samples from the Marion County (Indianapolis, Ind.) Coroner’s office of people who had committed suicide, the investigators found significantly higher levels of expression of ANK3 in older (middle aged) patients than in younger patients, and a shift towards higher ANK3 levels in those who had committed suicide. Higher levels of ANK3 have also been reported independently by others in individuals with Hutchinson-Gilford progeria syndrome, a form of accelerated aging.

Adding genes that had scored nearly as high as ANK3 in the Convergent Functional Genomics analysis to create a panel of biomarkers showed similar but somewhat stronger results, particularly among those who had committed suicide.

Mitochondrial dysfunction was the top biological pathway where the top candidate genes for mood and stress-modulated longevity mapped. Over the last decade, accumulating evidence has suggested a causative link between mitochondrial dysfunction and aging.

A few of the genes identified in this study are changed in opposite direction in longevity compared to previous reports in Alzheimer’s disease, raising the possibility that the treatment of mood and stress disorders earlier in life might have an impact on later life Alzheimer’s disease.

A large number of top genes identified in this study were changed in opposite direction in longevity compared to patterns of expression in suicide revealed by previous studies from the Niculescu group, suggesting the possibility of an evolutionary organismal “life switch,” actively controlled by mood and stress.

Bioinformatics drug repurposing analyses revealed a series of compounds that may act on these genes and promote longevity, such as the relatively innocuous omega-3 fatty acid DHA (docosahexaenoic acid), piracetam, quercetin, vitamin D and resveratrol, along with a series of existing drugs, such as estrogen-like compounds, antidiabetics and rapamycin.

The authors said that “these studies uncover ANK3 and other genes in our dataset as biological links between mood, stress and lifespan, that may be biomarkers for biological age as well as targets for personalized preventive or therapeutic interventions.”

{A long line of research links poverty and depression. Now, a study by Duke University scientists shows how biology might underlie the depression experienced by high-risk adolescents whose families are socio-economically disadvantaged.}

The study, published May 24, 2016 in the journal Molecular Psychiatry, combined genetics, brain imaging and behavioral data gathered as adolescents were followed for more than three years as part of a larger study.

The results are part of a growing body of work that may lead to biological predictors that could guide individualized depression-prevention strategies.

Adolescents growing up in households with lower socioeconomic status were shown to accumulate greater quantities of a chemical tag on a depression-linked gene over the course of two years. These “epigenetic” tags work by altering the activity of genes. The more chemical tags an individual had near a gene called SLC6A4, the more responsive was their amygdala — a brain area that coordinates the body’s reactions to threat — to photographs of fearful faces as they underwent functional MRI brain scans. Participants with a more active amygdala were more likely to later report symptoms of depression.

“This is some of the first research to demonstrating that low socioeconomic status can lead to changes in the way genes are expressed, and it maps this out through brain development to the future experience of depression symptoms,” said the study’s first author Johnna Swartz, a Duke postdoctoral researcher in the lab of Ahmad Hariri, a Duke professor of psychology and neuroscience.

Adolescence is rarely an easy time for anyone. But growing up in a family with low socioeconomic status or SES — a metric that incorporates parents’ income and education levels — can add chronic stressors such as family discord and chaos, and environmental risks such as poor nutrition and smoking.

“These small daily hassles of scraping by are evident in changes that build up and affect children’s development,” Swartz said.

The study included 132 non-Hispanic Caucasian adolescents in the Teen Alcohol Outcomes Study (TAOS) who were between 11 and 15 years old at the outset of the study and came from households that ranged from low to high SES. About half of the participants had a family history of depression.

“The biggest risk factor we have currently for depression is a family history of the disorder,” said study co-author Douglas Williamson, principal investigator of TAOS and professor of psychiatry and behavioral sciences at Duke. “Our new work reveals one of the mechanisms by which such familial risk may be manifested or expressed in a particular group of vulnerable individuals during adolescence.”

The group’s previous work, published last year in the journal Neuron, had shown that fMRI scan activity of the amygdala could signal who is more likely to experience depression and anxiety in response to stress several years later. That study included healthy college-aged participants of Hariri’s ongoing Duke Neurogenetics Study (DNS), which aims to link genes, brain activity, and other biological markers to a risk for mental illness.

This study asked whether higher activity in the same brain area could predict depression in the younger, at-risk TAOS participants. Indeed, about one year later, these individuals (now between 14 and 19 years of age) were more likely to report symptoms of depression, especially if they had a family history of the disorder.

Swartz said the new study examined a range of socioeconomic status and did not focus specifically on families affected by extreme poverty or neglect. She said the findings suggest that even modestly lower socioeconomic status is associated with biological differences that elevate adolescents’ risk for depression.

Most of the team’s work so far has focused on epigenetic chemical tags near the SLC6A4 gene because it helps control the brain’s levels of serotonin, a neurochemical involved in clinical depression and other mood disorders. The more marks present just upstream of this gene, the less likely it is to be active.

In 2014, Williamson and Hariri first showed that the presence of marks near the SLC6A4 gene can predict the way a person’s amygdala responds to threat. That study included both Williamson’s TAOS and Hariri’s DNS participants, but had looked at the chemical tags at a single point in time.

Looking at the changes in these markers over an extended time is a more powerful way to understand an individual’s risk for depression, said Hariri, who is also a member of the Duke Institute for Brain Sciences.

The team is now searching the genome for new markers that would predict depression. Ultimately, a panel of markers used in combination will lead to more accurate predictions, Swartz said.

They also hope to expand the age ranges of the study to include younger individuals and to continue following the TAOS participants into young adulthood.

“As they enter into young adulthood they are going to be experiencing more problems with depression or anxiety — or maybe substance abuse,” Hariri said. “The extent to which our measures of their genomes and brains earlier in their lives continue to predict their relative health is something that’s very important to know and very exciting for us to study.”

{Imagine, for a moment, you are a parent trying to limit how much dessert your sugar-craving young children can eat. “You can have cake or ice cream,” you say, confident a clear parental guideline has been laid out. But your children seem to ignore this firm ruling, and insist on having both cake and ice cream. Are they merely rebelling against a parental command? Perhaps. But they might be confusing “or” with “and,” as children do at times, something studies have shown since the 1970s. What seems like a restriction to the parent sounds like an invitation to the child: Have both!}

Imagine, for a moment, you are a parent trying to limit how much dessert your sugar-craving young children can eat.

“You can have cake or ice cream,” you say, confident a clear parental guideline has been laid out.

But your children seem to ignore this firm ruling, and insist on having both cake and ice cream. Are they merely rebelling against a parental command? Perhaps. But they might be confusing “or” with “and,” as children do at times, something studies have shown since the 1970s. What seems like a restriction to the parent sounds like an invitation to the child: Have both!

But why does this happen? Now a study by MIT linguistics professors and a team from Carleton University, based on an experiment with children between the ages of 3 and 6, proposes a new explanation, with a twist: In examining this apparent flaw, the researchers conclude that children deploy a more sophisticated mode of logical analysis than many experts have previously realized.

Indeed, say the linguists, children use almost entirely the same approach as adults when it comes to evaluating potentially ambiguous sentences, by testing and “strengthening” them into sentences with more precise meanings, when disjunction and conjunction (“or” and “and”) are involved.

While using this common approach, however, children do not test how a sentence would change if “and” were directly substituted for “or.” This more modest procedural problem is what leads to the confusion about cake and ice cream.

“Children seem to interpret disjunction like conjunction,” observes Danny Fox, the Anshen-Chomsky Professor in Language and Thought at MIT and co-author of a paper detailing the study. However, Fox adds, although “it has been claimed children are very different from adults in the interpretation of logical words,” the study’s larger implication is almost the opposite — namely that “the child is [otherwise] identical to the adult, but there is a very small parameter that distinguishes them.”

Quirky as this finding seems, it confirms a specific prediction Fox and some other researchers had made, based on previous studies in formal semantics (the area of linguistics that investigates the logic of natural language use). As such, the study reinforces what we know about the procedures both children and adults deploy in “and/or” matters.

“There’s a certain kind of computation we can now say both children and adults do,” says Raj Singh PhD ’08, an associate professor of cognitive science at Carleton University and the lead author of the new report.

The paper, “Children interpret disjunction as conjunction: Consequences for theories of implicature and child development,” is being published in the journal Natural Language Semantics. The co-authors are Singh; Fox; Ken Wexler, emeritus professor of psychology and linguistics at MIT; Deepthi Kamawar, an associate professor of psychology at Carleton University; and Andrea Astle-Rahim, a recent PhD graduate from Carleton University.

What adults do: the two-step

To understand how children conflate “or” with “and,” first consider how adults normally clarify what sentences mean. Suppose you have a dozen cookies in a jar on your desk at work, and go to a meeting. When you come back, a colleague tells you, “Marty ate some of the cookies.”

Now suppose you find out that Marty actually ate all 12 cookies. The previous sentence — “Marty ate some of the cookies” — may still be true, but it would be more accurate to say, “Marty ate all of the cookies.”

To make this evaluation, adults compute “scalar implicatures,” a technical phrase for thinking about the implications of the logical relationship between a sentence and its alternatives. For “Marty ate some of the cookies,” there is a two-step computation. The first step is to think through some alternatives, such as what happens if you substitute “all” for “some” (leading to “Marty ate all of the cookies”). The second step is to realize that this alternative spells out a specific new meaning — that all 12 cookies have been eaten, not just a few of them.

We then realize the sentence “Marty ate some of the cookies” more accurately means: “Marty ate some, but not all, of the cookies.” And now we have a “strengthened” version of the first sentence.

The same process applies to the sentence, “Jane ate cake or ice cream.” The sentence is true if Jane ate one or the other, and still technically true if she ate both. But once we compute the scalar implicatures, we realize that “Jane ate cake or ice cream” is a “strengthened” way of saying she ate one or the other, but not both.

Fox has conducted extensive research over the last decade formalizing our computations of scalar implicatures and identifying areas where tiny differences in the logical “space of alternatives” can have far-reaching consequences. The current paper stems in part from work Singh pursued as a doctoral student collaborating with Fox at MIT.

Why “or” and “and” merge for children

The research team conducted the study’s experiment by testing 59 English-speaking children and 26 adults in the Ottawa area. The children ranged in age from 3 years, 9 months, to 6 years, 4 months. The linguists gave the subjects a series of statements along with pictures, and asked them to say whether the statements were true or false.

For instance: The children were shown a picture with three boys holding an apple or a banana, along with the statement, “Every boy is holding an apple or a banana,” and then asked to say if the statement was true or false. The children were asked to do this for a full range of scenarios — such as one boy holding one type of fruit and two boys holding the other — along with a varying set of “and/or” statements. The researchers repeated five sets of such trials, with the pictures changing each time.

The results suggest that children are computing scalar implicatures when they evaluate the statements — but they largely do not substitute disjunctions and conjunctions when testing out the possible meaning of sentences, as adults do.

That means when children hear “cake or ice cream,” they are generally not replacing “or” in the phrase with “and,” to test what would happen. Without that contrast, the children still “strengthen” the meaning of “or,” but they strengthen it to mean “and.” Thus “or” and “and” can blur together for children.

“They [children] don’t use ‘cake and ice cream’ as an alternative,” Fox says. “As a result, ‘cake or ice cream’ is expected, if we are right about the nature of the computation, to become ‘cake and ice cream’ for the children.”

And while we tend to think children are wrong to draw that conclusion, it is still the result of computing scalar implicatures — it just happens that, as Singh observes, those computations create divergent outcomes for children and adults.

A universal process

The researchers say they agree with the need to examine that transition to the adult pattern of strengthening. In the meantime, they hope colleagues will consider the additional evidence the study provides about the formal logic underlying our language use.

“The computational system of language is actually telling us how to do certain kinds of thinking,” Wexler suggests. “It isn’t us just trying to [understand] things pragmatically.”

Additionally, the scholars believe evidence from other languages besides English supports their conclusions. In both Walpiri, a language of indigenous Australians, and American Sign Language, there is a single connective word that functions as both “or” and “and” and appears subject to the strengthening process identified for children. And, Singh notes, linguists are now replicating the study’s findings in French and Japanese.

In general, Fox observes, across languages, and for children and adults alike, “The remarkable logical fact is that when you take ‘and’ out of the space of alternatives, ‘or,’ becomes ‘and.’ This, of course, relies on the nature of the computation that we’ve postulated, and, hence, the results of the study provide confirmation of a form that I find rather exciting.”

So, yes, your children may not understand what you mean about dessert. Or perhaps they are just being willful. But if they confuse “or” with “and,” then they are not being childish — at least not in the way you may think.

{Studying fruit flies, whose sleep is remarkably similar to that in people, Johns Hopkins researchers say they’ve identified brain cells that are responsible for why delaying bedtime creates chronic sleepiness.}

In a report on the research published online on May 19, 2016 in Cell, the scientists say they found a group of brain cells in charge of so-called sleep drive that becomes more active the longer flies are kept awake. The same mechanism, they say, also plays a role in putting the flies to sleep and keeping them that way.

The findings may offer insight into human sleep disorders and open up new strategies to promote long-lasting sleep for those with chronic insomnia who don’t respond to available sleep drugs, they say.

“Although fruit flies look very different from people on the surface, they actually share many of the same genes and even behaviors,” says Mark Wu, M.D., Ph.D., associate professor of neurology at the Johns Hopkins University School of Medicine. “And with what we believe is the first identification a mechanism behind the adjustable nature of sleep drive, researchers can look for the same processes in mammals, including, one day, in humans.”

In their search for sleep-regulating cells, Wu’s team used genetic engineering to turn on small numbers of neurons in more than 500 fruit fly strains. They then measured how these flies slept when these neurons “fired.” Several strains continued to sleep for several hours even after they turned off the neurons, stopping them from firing and suggesting that the researchers triggered sleep drive in these flies, which led to the persistent sleepiness.

Using fluorescent microscopy, the scientists then examined the fly brains to specifically pinpoint the identity and location of the sleep drive-inducing cells. The firing neurons were genetically engineered to glow green. They were found in a structure called the ellipsoid body (see photo) and are known as the R2 neurons.

To pin down more of what was going on, the researchers blocked the neurons from firing by genetically engineering the R2 neurons to make tetanus toxin, which silences the cells. The flies with the silenced R2 neurons slept on their normal schedule, but when the flies with the silenced R2 neurons were deprived of sleep during the night by mechanically shaking their vial houses, they got about 66 percent less “rebound sleep” compared to control flies, suggesting that they felt less sleepy after sleep deprivation.

Next, the researchers tested how fly R2 neurons behaved on their own in awake, sleeping or sleep-deprived fruit flies. They used tiny electrodes to measure the firing of the R2 neurons in well-rested, awake fruit flies; in fruit flies that were an hour into their sleep cycle; and in fruit flies after 12 hours of sleep deprivation.

In the well-rested fruit flies, the neurons fired only about once per second and were the least active. In the sleeping fruit flies, the neurons fired almost four times a second. In the sleep-deprived fruit flies, the neurons were the most active, firing at about seven times per second.

“These R2 neurons have higher firing rates the more sleep-deprived the fruit flies were and firing of these neurons puts flies to sleep, suggesting that we’ve identified the key cells responsible for sleep drive,” says Wu.

Wu says it’s long been thought that getting to sleep requires an increase in sleep-promoting chemicals in specific parts of the brain as night and bedtime approach in the normal 24-hour sleep-wake cycle. However, he says, these chemicals last for only a few minutes at a time, so it has been puzzling how they can account for sleep drive that lasts hours.

As an answer to this question, Wu and colleagues used a genetic technique to light up the places on the surface of the R2 neurons where they actively release small chemical neurotransmitters, sending information to neighboring cells. Compared to well-rested flies, sleep-deprived flies had an increase in the number and size of the places releasing the neurotransmitter, and they appeared much brighter. Wu says these changes in number of neurotransmitter release sites account for how the neurons are able to adjust over time using a system for sleep drive that works over a period of hours, rather than minutes, like the known sleep-promoting chemicals. This flexible system can adjust to times when the flies are sleep-deprived or when they are just nearing their normal bedtime. He adds that the sleep drive process in the R2 neurons works similarly to how memories are encoded in other types of neurons, where changes in the neuron’s information-sending and receiving parts adjust over time.

“Figuring out how sleep drive works should help us one day figure out how to treat people who have an overactive sleep drive that causes them to be sleepy all the time and resistant to current therapies,” Wu says.

{The geologic shape of what were once shorelines through Mars’ northern plains convinces scientists that two large meteorites — hitting the planet millions of years apart — triggered a pair of mega-tsunamis. These gigantic waves forever scarred the Martian landscape and yielded evidence of cold, salty oceans conducive to sustaining life.}

“About 3.4 billion years ago, a big meteorite impact triggered the first tsunami wave. This wave was composed of liquid water. It formed widespread backwash channels to carry the water back to the ocean,” said Alberto Fairén, Cornell visiting scientist in astronomy and principal investigator at the Center of Astrobiology, Madrid.

Fairén, who with lead author Alexis Rodriguez of the Planetary Science Institute and 12 others, published their work in Scientific Reports (May 19), a publication of the journal Nature.

The scientists found evidence for another big meteorite impact, which triggered a second tsunami wave. In the millions of years between the two meteorite impacts and their associated mega-tsunamis, Mars went through frigid climate change, where water turned to ice, Fairén said: “The ocean level receded from its original shoreline to form a secondary shoreline, because the climate had become significantly colder.”

The second tsunami formed rounded lobes of ice. “These lobes froze on the land as they reached their maximum extent and the ice never went back to the ocean — which implies the ocean was at least partially frozen at that time,” he said. “Our paper provides very solid evidence for the existence of very cold oceans on early Mars. It is difficult to imagine Californian beaches on ancient Mars, but try to picture the Great Lakes on a particularly cold and long winter, and that could be a more accurate image of water forming seas and oceans on ancient Mars.”

These icy lobes retained their well-defined boundaries and their flow-related shapes, Fairén said, suggesting the frozen ancient ocean was briny. “Cold, salty waters may offer a refuge for life in extreme environments, as the salts could help keep the water liquid. … If life existed on Mars, these icy tsunami lobes are very good candidates to search for biosignatures,” he said.

“We have already identified some areas inundated by the tsunamis where the ponded water appears to have emplaced lacustrine sediments, including evaporites,” Rodriguez said. “As a follow-up investigation we plan to characterize these terrains and assess their potential for future robotic or human in-situ exploration.”

The research, “Tsunami Waves Extensively Resurfaced the Shorelines of an Early Martian Ocean,” was funded by NASA. Fairén was supported by the European Research Council.

A chance fossil discovery in Montana a decade ago has led to the identification of an audacious new species of horned dinosaur. The international research team that described the plant-eating dinosaur was led by a scientist at the Canadian Museum of Nature. The results are published today in the online science journal PLOS ONE.

The museum now houses the specimen in its national fossil collection, which includes some of the best examples of horned dinosaurs in the world. Museum palaeontologist Dr. Jordan Mallon completed the scientific analysis that pinned down the dinosaur as a new species. It is one among a growing number of newly discovered ceratopsids (four-legged dinosaurs generally characterized by horns on the face and elaborate head frills).

Mallon has bestowed the scientific name Spiclypeus shipporum (spi-CLIP-ee-us ship-OR-um) on the dinosaur, which lived about 76 million year ago. Spiclypeus is a combination of two Latin words meaning “spiked shield,” referring to the impressive head frill and triangular spikes that adorn its margins. The name shipporum honours the Shipp family, on whose land the fossil was found near Winifred, Montana.

About half of the skull, as well as parts of the dinosaur’s legs, hips and backbone had been preserved in the silty hillside that once formed part of an ancient floodplain.

“This is a spectacular new addition to the family of horned dinosaurs that roamed western North America between 85 and 66 million years ago,” explains Mallon, who collaborated with researchers in Canada and the United States. “It provides new evidence of dinosaur diversity during the Late Cretaceous period from an area that is likely to yield even more discoveries.”

What sets Spiclypeus shipporum apart from other horned dinosaurs such as the well-known Triceratops is the orientation of the horns over the eyes, which stick out sideways from the skull. There is also a unique arrangement to the bony “spikes” that emanate from the margin of the frill–some of the spikes curl forward while others project outward.

“In this sense, Spiclypeus is transitional between more primitive forms in which all the spikes at the back of the frill radiate outward, and those such as Kosmoceratops in which they all curl forward,” says Mallon.

While the fossil now has a scientific moniker, it is more commonly known by its nickname “Judith,” after the Judith River geological formation where it was found. Until it was purchased by the museum in 2015, the fossil had remained in the official possession of Dr. Bill Shipp, who found it while exploring his newly acquired property in 2005.

Shipp invested time and money to excavate and prepare the bones, aided by volunteers and palaeontologists including the PLOS ONE study co-authors Chris Ott and Peter Larson. “Little did I know that the first time I went fossil hunting I would stumble on a new species,” explains Shipp, a retired nuclear physicist who became a fossil enthusiast after moving to his dinosaur rich area of Montana. “As a scientist, I’m really pleased that the Canadian Museum of Nature has recognized the dinosaur’s value, and that it can now be accessed by researchers around the world.”

Apart from the horns and frill bones that helped define Judith as a new species, close examination of some of its other bones reveal a story of a life lived with pain. Judith’s upper arm bone (humerus) shows distinct signs of arthritis and osteomyelitis (bone infection)–determined following analysis by Dr. Edward Iuliano, a radiologist at the Kadlec Regional Medical Cener, in Richland, Washington.

“If you look near the elbow, you can see great openings that developed to drain an infection. We don’t know how the bone became infected, but we can be sure that it caused the animal great pain for years and probably made its left forelimb useless for walking,” explains Mallon. Despite this trauma, analysis of the annual growth rings inside the dinosaur’s bones by the Royal Ontario Museum’s Dr. David Evans suggest it lived to maturity. The dinosaur would have been at least 10 years old when it died.

Mallon and his team note that there are now nine well-known dinosaur species (including Spiclypeus shipporum), from Montana’s Judith River Formation. Some are also found in Alberta, which has a much richer fossil record, but others such as Spiclypeus are unique to Montana. Significantly, Mallon says that none of the species are shared with more southerly states, suggesting that dinosaur faunas in western North America were highly localized about 76 million years ago. Mallon’s prior research has shown that such species-rich communities may have been enabled by dietary specializations among the herbivores, a phenomenon more commonly known as niche partitioning.

A public exhibit about Spiclypeus shipporum, will open May 24 at the Canadian Museum of Nature in Ottawa. It will include a reconstruction of the dinosaur’s skull, the diseased humerus, and other bones from this amazing fossil find.