It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Friday, April 30, 2021
Digital mental health interventions for young people are perceived promising, but are they effective
COLUMBIA UNIVERSITY'S MAILMAN SCHOOL OF PUBLIC HEALTH
April 29, 2021 -An increasing number of digital mental health interventions are designed for adolescents and young people with a range of mental health issues, but the evidence on their effectiveness is mixed, according to research by Columbia University Mailman School of Public Health and Spark Street Advisors.
Computerized cognitive behavioral therapy was found effective for anxiety and depression in adolescents and young people holding promise for increasing access to mental health treatment for these conditions. However, the effectiveness of other digital interventions, including therapeutic video games, mobile apps, or social networking sites, and addressing a range of other mental health outcomes remain inconclusive. The findings are published online in the journal JMIR Mental Health.
According to UNICEF, nearly 1 in 5 adolescents experience a mental health disorder each year but because of barriers to accessing and seeking care, most remain undiagnosed and untreated.
"While there is evidence that some interventions can be effective when delivered digitally, it is still somewhat of a wild west when it comes to digital mental health apps," said Nina Schwalbe, adjunct assistant professor of Population and Family Health at Columbia Mailman School.
The researchers conducted an analysis of 18 systematic reviews and meta-analyses of digital health interventions. In addition to the findings on computerized cognitive behavioral therapy, some therapeutic areas of digital interventions improved outcomes relative to controls for those who are on the waitlist for services, suggesting that the interventions can be used for supplementing and supplanting traditional mental health treatment in cases where access to care is limited or wait times to access are long.
The Investigators point out that the vast majority - over 90 percent - of interventions studied are implemented in high-income countries, with very little information about the background of participants. Therefore, the generalizability of the findings to young people from different socioeconomic, cultural, racial, or other communities is weak. ""It is critical to assess the effectiveness among different racial and ethnic groups and across geographies," observed Susanna Lehtimaki of Spark Street Advisors.
"There was also no indication of costs of developing the tools or long-term benefits," noted Susanna Lehtimaki of Spark Street Advisors. "Moving forward with effective digital health interventions, it will be important to understand how they fit within the public health ecosystem and to what extent they are effective across a range of settings with different resources or populations."
According to the research, digital mental health interventions were well accepted by those 10 to 24 years of age, however, dropout was common and adherence weak. Engagement of a health professional, peer, or parent as part of the digital intervention were found to strengthen the effectiveness.
Schwalbe notes, "In the spirit of "do no harm" it is really important that the excitement over the promise of digital mental health interventions does not cloud the need for high quality effectiveness studies in a range of settings and with a diverse group of youth." She also notes, "it should go without saying that adolescents also need to be consulted in every stage of the design process and while it may be assumed that young people prefer digital services, we need to continually challenge whether this is true."
###
Co-authors include Jana Martic, Spark Street Advisors; Brian Wahl, Spark Street Advisors and Bloomberg School of Public Health; and Katherine Foster, University of Washington.
Columbia University Mailman School of Public Health
Founded in 1922, the Columbia University Mailman School of Public Health pursues an agenda of research, education, and service to address the critical and complex public health issues affecting New Yorkers, the nation and the world. The Columbia Mailman School is the seventh largest recipient of NIH grants among schools of public health. Its nearly 300 multi-disciplinary faculty members work in more than 100 countries around the world, addressing such issues as preventing infectious and chronic diseases, environmental health, maternal and child health, health policy, climate change and health, and public health preparedness. It is a leader in public health education with more than 1,300 graduate students from 55 nations pursuing a variety of master's and doctoral degree programs. The Columbia Mailman School is also home to numerous world-renowned research centers, including ICAP and the Center for Infection and Immunity. For more information, please visit http://www.mailman.columbia.edu.
Partnerships between researchers, policymakers and practitioners improve early childhood education
New York, NY--Research-practice partnerships (RPPs), long-term collaborations between researchers, policy makers and practitioners, represent an especially promising strategy for making sure that all children benefit from early childhood education, according to a journal released today by Princeton University and the Brookings Institution.
The journal, Future of Children, edited by Daphna Bassok of the University of Virginia and Pamela Morris of New York University's Steinhardt School, argues that RPPs are crucial for solving today's most pressing question in early childhood education--how to deliver high-quality prekindergarten programs at scale.
"Too often there is a disconnect between the questions researchers tackle and the ones that are more urgent and salient for policy makers or practitioners," said Bassok. "The findings from rigorous, well-designed research studies may not be particularly useful for addressing the real-life complexity that educators and policymakers face."
"The idea of research practice partnerships is that through close collaborations, researchers can do work that really helps policy makers address the big problems they are tackling and do the work fast enough to actually inform change," continued Morris. "Our hope is that this journal makes that clear."
RPPs are Designed to Improve Educational Outcomes
RPPs are defined by longevity, mutual decision-making and compromise, and the commitment of both parties to large-scale, systems-level problem solving, rather than a single project or research question.
In study after study, early childhood education programs developed by researchers have shown large benefits, holding out the promise of substantially narrowing the achievement gap between disadvantaged children and their better-off peers. But when cities and states establish large-scale prekindergarten programs, Bassok and Morris noted, the results are often far more modest. The important questions today aren't about whether early childhood education "works," but about how to invest limited resources to improve the quality of large-scale prekindergarten programs, support the early childhood workforce, and reach the children who need the most help.
"Delivering effective early childhood education at scale remains elusive," said Bassok. "Findings from promising research studies rarely make their way into early childhood practice; at the same time, policy and practice decisions are often made without research evidence to guide them."
That's partly because policy makers and practitioners have different priorities and work on different timelines than researchers do. Through collaboration, compromise, and long-term commitment, RPPs can help bridge the gap and produce research that's relevant and useful to policy makers and practitioners, while at the same time offering scholars opportunities for broad and innovative research wouldn't be possible in one-off studies of a single program or topic.
The Journal is a User Manual for Partnerships
Each article in the journal describes how a successful early childhood RPP confronted a major challenge or exploited an unexpected opportunity in the process of working together to create a research or funding agenda, develop measurement tools, take innovation to scale, navigate conflicting timelines, find a balance between academic rigor and feasibility, or build research capacity. In this sense, the journal offers both a user manual and a road map for future partnerships to follow.
"The COVID-19 pandemic has underlined the benefits of RPPs," Morris said. "Where RPPs were in place, researchers used their familiarity with the local context to help ease the sudden transition to remote learning."
For example, as COVID-19 spread in New York City, researchers in an established RPP there quickly assembled materials about remote learning, including a tool kit for teachers citywide, and offered resources to answer policy makers' most urgent questions.
"The pandemic has created large gaps in the services provided to our youngest learners, and opened the door for new collaborations as policy systems race to meet children's needs," continued Morris. "In this context, RPPs can support efforts to rebuild and reimagine early childhood education systems that can help all of our nation's children acquire strong foundations for kindergarten and beyond."
###
Visit http://www.futureofchildren.org to read "Research-Practice Partnerships to Strengthen Early Education" as well as past issues of the Future of Children.
About the Steinhardt School of Culture, Education, and Human Development
Located in the heart of New York City's Greenwich Village, NYU's Steinhardt School of Culture, Education and Human Development prepares students for careers in the arts, education, health, media and psychology. Since its founding in 1890, the Steinhardt School's mission has been to expand human capacity through public service, global collaboration, research, scholarship, and practice. To learn more about NYU Steinhardt, visit steinhardt.nyu.edu.
Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.
Large study suggests that symptom screening, other measures can eliminate most or all excess risk of developing COVID-19-like symptoms or testing positive for COVID-19
JOHNS HOPKINS UNIVERSITY BLOOMBERG SCHOOL OF PUBLIC HEALTH
People living with a child who attends school in-person have an increased risk of reporting evidence of COVID-19, but teacher masking, symptom screening, and other mitigation measures in schools may be able to minimize that excess risk, suggests a study led by researchers at the Johns Hopkins Bloomberg School of Public Health.
For their study, the researchers analyzed nearly 600,000 responses from an ongoing Facebook-based COVID-19 symptom survey in the United States over two periods between November 2020 and February 2021 before vaccines were widely available in the U.S. The researchers found that those living with a child engaged in full-time, in-person pre-K-to-12 schooling were about 38 percent more likely to report COVID-19-like symptoms such as fever, cough, or difficulty breathing, compared to those living with a child schooled exclusively in a home setting.
A key finding was that school-based mitigation measures--the survey asked about 14 mitigation measures--were associated with less risk per mitigation measure. For example, 9 percent less risk of COVID-related illness per measure, and 7 percent less risk of a positive SARS-CoV-2 test per measure. Each additional mitigation measure reduced risk. Teacher masking and daily symptom screening appeared to be the strongest risk reducers.
The study was published online April 29 in Science.
The analysis included three outcomes as reported by survey respondents: COVID-19-like illness, i.e., fever and respiratory symptoms within the last 24 hours; loss of taste or small within the last 24 hours; and a positive COVID-19 test in the last 14 days.
The survey responses indicated that most pre-K-to-12 schools had some mitigation measures in place, such as mask mandates for teachers, daily screening of students and teachers for symptoms, and curtailment of extracurricular activities. The researchers found that when schools used seven or more mitigation measures, the excess risk associated with in-person schooling mostly disappeared--and completely disappeared when 10 or more mitigation measures were reported.
"These findings support the idea that mitigation measures at schools can greatly reduce the excess COVID-19 risk to adults living with children who attend school in-person," says study first author Justin Lessler, an associate professor in the Department of Epidemiology at the Bloomberg School.
The issue of in-person schooling has been much debated in the United States from the start of the COVID-19 pandemic, leading to different school policies across the country. This policy diversity effectively set in motion a "natural experiment" with schooling and COVID-19 risk in the U.S. population. A chief concern has been that children going to school every day, even if they are not very susceptible to COVID-19 themselves, may bring home the virus to parents and other adult family members who are at higher risk of disease.
To examine these issues, Lessler and colleagues used the COVID-19 Symptom Survey, an ongoing Facebook-based survey managed by Carnegie Mellon University's Delphi Group in collaboration with Facebook that garners about 250,000 responses per week. The researchers looked at responses during two recent periods--roughly from Thanksgiving to Christmas last year and mid-January to mid-February this year--from respondents in households where at least one child was enrolled in a school, from pre-kindergarten through high school. Of the 576,051 people in this group, about 49 percent, or 284,789, reported being in a household with a child attending pre-K-to-12 school in-person rather than online or homeschooled.
In their analysis, Lessler and colleagues examined how the in-person school group differed from the online or homeschooled group in terms of reported COVID-19-related symptoms and outcomes. They adjusted the results to account for obvious confounding factors such as differences in local COVID-19 rates.
In addition to the 38 percent increase in the odds of getting a COVID-19-related illness among respondents in households with an in-person-schooled child, the researchers found a 21 percent increase in the odds for the loss of taste or smell--one of the core symptoms of COVID-19--and a 30 percent increase in the odds for testing positive for SARS-CoV-2 infection in the previous two weeks.
The strength of these associations appeared to increase with grade level. At the K and pre-K level, the association with COVID-19 outcomes was not significant for all outcomes, but the strength of those associations rose steadily, peaking at the grade 9-12 level--where the excess risk of a recent positive SARS-CoV-2 test for household members was over 50 percent. These findings are consistent with past studies suggesting less susceptibility to SARS-CoV-2 infection and COVID-19 illness among younger children compared to older ones.
The survey data included responses about COVID-19 mitigation measures in schools attended by children in the respondent's household. These mitigation measures included mask mandates for teachers and students, extra space between desks, suspension of school clubs, sports, and other extracurricular activities, and daily symptom screening among teachers and students. Respondents with a child in their household attending school in person reported a mean of 6.7 mitigation measures at school--with significant variations in that figure across the country, from a mean of 4.6 measures in South Dakota schools to 8.9 in Vermont schools.
The analysis also suggested that most of the increased COVID-19-related risk was concentrated in schools with fewer than seven mitigation measures, and that in-person schooling was not associated with increased risk for any COVID-19-related outcomes among respondents living with children in schools with ten or more measures.
"Because the study is based on a self-reported symptom survey and a setting where we can't randomize students to different schooling modes and mitigation measures, it has limitations," Lessler says. "But having hundreds of thousands of respondents and the ability to control for geographic and individual-level characteristics helps make up for those limitations."
He and his colleagues plan to follow up with studies of how in-person schooling and school-based mitigation measures affect community-wide spread of COVID-19.
"Household COVID-19 risk and in-person schooling" was co-authored by Justin Lessler, M. Kate Grabowski, Kyra Grantz, Elena Badillo-Goicoechea, C. Jessica Metcalf, Carly Lupton-Smith, Andrew Azman, and Elizabeth Stuart.
###
Support for the research was provided by a Johns Hopkins University Discovery Award, Johns Hopkins University COVID-19 Modeling and Policy Hub Award, and the U.S. Department of Health and Human Services.
Six out of every 10 teachers believe that changing the design of the classroom is key to improving learning
Several studies have already acknowledged the benefits of a suitably designed classroom.
IMAGE: SCIENCE TELLS US THAT WE LEARN BETTER AND MORE BY COLLABORATING, AND THEREFORE THE SPACE MUST FAVOUR THIS view more
CREDIT: (PHOTO: SMARTCLASSROOMPROJECT.COM)
The image of rows of chairs and desks facing a teacher at a blackboard has been a reality for decades. However, research reveals that this way of organizing the classroom furniture in schools is not the best way for favouring the learning process. Especially if the needs of 21st-century students are taken into account, who, according to the OECD, require a social environment that fosters autonomy, flexibility, decision-making capacity and the connection of knowledge by individual students or through teamwork.
It is also the opinion of 6 out of every 10 teachers that changing the design of the classroom is key to improving learning. This was the result of a recent study conducted by researchers of the Universitat Oberta de Catalunya (UOC), Universitat Autònoma de Barcelona (UAB), Universitat de Barcelona (UB), Universitat de Vic (UVic) and Universidad Simón BolÃvar (USB), in which 847 preschool, primary and secondary school teachers from 40 schools participated. "We assume that's what the spaces should be like without giving it much thought or without connecting what we're innovating in terms of methodology with the place in which we're going to put that into practice," said Guillermo Bautista, member of the Smart Classroom Project research group of the UOC and principal investigator in this study. That's why we need to make the Smart Learning Space a reality: "a space that meets any learning need or proposal, that is flexible and not zoned, in which physical and psychological well-being are prioritized as the foundations upon which the learning activity can take place, in which the pupils play a proactive and autonomous role," said Bautista.
Several studies have already acknowledged the benefits of a suitably-designed classroom. This was one of the reasons why the Consorci d'Educació de Barcelona started replacing the furniture in 487 classrooms a few weeks ago, whilst also reorganizing the spaces to obtain motivating environments that encourage discovery. And, as the authors of the UOC-led study point out, it's that the skills and learning needs of today's pupils not only oblige us to rethink our teaching practices or the inclusion of digital resources, they also require changes in the learning spaces in general.
Guillermo Bautista demonstrates this with an example: as he explains, science tells us that we learn better and more by collaborating, and therefore the space must favour this collaboration and interaction, also taking into account what research tells us about collaborative learning. If we organize the activity with groups of four students based on a challenge or a project, it would be logical that the space should be suitable to enable the group to collaborate and also enable a certain amount of autonomy for using the resources it needs, for moving, looking around, experimenting, and self-organizing, etc. "This means that not all of the groups will be doing the same thing at the same time, and the same resources will not be necessary for everyone. The activity in the classroom is diverse and the space must constantly respond to this organizational diversity of use, resources, movements," he explained.
However, the strong assumption upheld for decades that the classroom is as it is, has resulted in us proposing few changes. And when these are finally being proposed, the direction of these changes is not easy to decide upon, "and that is why our research is necessary, to help establish criteria so that the space is changed with guarantees," he said.
Changes in the design of secondary school classrooms also
Currently, most teachers negatively rate the organization of the environment in their classroom. This is one of the findings of the study, whereby low or moderate scores were obtained regarding the suitability of current classrooms to serve as comprehensive learning spaces. But differences exist between the different levels of education, as the design of preschool and primary education learning spaces is generally more flexible, collaborative and personal, affirm the authors of the study, who point to a possible reason for this scenario. "It is precisely in the infant and primary stages where teaching trends such as those applied since the early 20th century (in which the spaces, their layout, furniture, etc. were already linked to clear educational meanings) have been most present and usually more visible," said Angelina Sánchez-MartÃ, researcher of the Smart Classroom Project and Serra Húnter professor at the Universitat Autònoma de Barcelona.
On the other hand, the traditional layout of the spaces is much more established among secondary school centres and teachers. That's why the authors of the study positively value the fact that during the study it was confirmed that there are teachers and centres from this stage of education who are aware that their spaces do not correspond with the methodologies that they want to implement. "The Smart Spaces that we have implemented as part of the research are co-designed, applying a thoroughness, rigorousness, and seeking to meet the highest objectives and results for learning proposed by each centre. And these spaces are needed in all of the stages," said Bautista.
Another result to highlight is that the teachers are especially critical when it comes to appraising the integration of technology in the classrooms. But in the opinion of the authors of the study, this data is not surprising as "it is precisely the new technologies that are threatening the traditional times and spaces, and therefore demand great flexibility and a constant adaptation to change, as well as a reformulation of the learning spaces", said Sánchez-MartÃ. She added that the possibilities that technological integration offers in terms of creating new ways to relate and learn "completely clashes with the very standardized design derived from the idea that schools must be based on classrooms per se, when this does not necessarily have to be the case."
CAPTION
example of a Smart classroom
CREDIT
(Photo: Smartclassroomproject.com
This research by the UOC supports Sustainable Development Goal (SDG) number 4, on Quality Education
This study has been financed by the RecerCaixa Smart Classroom project. Codesign of innovative learning environments. Investigating new classroom models.
UOC R&I
The UOC's research and innovation (R&I) is helping overcome pressing challenges faced by global societies in the 21st century, by studying interactions between technology and human & social sciences with a specific focus on the network society, e-learning and e-health. Over 500 researchers and 51 research groups work among the University's seven faculties and two research centres: the Internet Interdisciplinary Institute (IN3) and the eHealth Center (eHC).
The United Nations' 2030 Agenda for Sustainable Development and open knowledge serve as strategic pillars for the UOC's teaching, research and innovation. More information: research.uoc.edu. #UOC25years
How to level up soft robotics
Mechanical engineer offers perspective on the maturation of the field of soft robotics
The field of soft robotics has exploded in the past decade, as ever more researchers seek to make real the potential of these pliant, flexible automata in a variety of realms, including search and rescue, exploration and medicine.
For all the excitement surrounding these new machines, however, UC Santa Barbara mechanical engineering professor Elliot Hawkes wants to ensure that soft robotics research is more than just a flash in the pan. "Some new, rapidly growing fields never take root, while others become thriving disciplines," Hawkes said.
To help guarantee the longevity of soft robotics research, Hawkes, whose own robots have garnered interest for their bioinspired and novel locomotion and for the new possibilities they present, offers an approach that moves the field forward. His viewpoint, written with colleagues Carmel Majidi from Carnegie Mellon University and Michael T. Tolley of UC San Diego, is published in the journal Science Robotics.
"We were looking at publication data for soft robotics and noticed a phase of explosive growth over the last decade," Hawkes said. "We became curious about trends like this in new fields, and how new fields take root."
The first decade of widespread soft robotics research, according to the group, "was characterized by defining, inspiring and exploring," as roboticists took to heart what it meant to create a soft robot, from materials systems to novel ways of navigating through and interacting with the environment.
However
Small galaxies likely played important role in evolution of the Universe
Researchers find first-ever galaxy observed in a 'blow-away' state
IMAGE: THE UNIVERSITY OF MINNESOTA STUDY SHOWS THAT HIGH-ENERGY LIGHT FROM SMALL GALAXIES, LIKE THE POX 186 GALAXY DEPICTED ABOVE, MAY HAVE PLAYED A KEY ROLE IN THE REIONIZATION AND EVOLUTION... view more
CREDIT: CREDIT: PODEVIN, J.F., 2006
A new study led by University of Minnesota astrophysicists shows that high-energy light from small galaxies may have played a key role in the early evolution of the Universe. The research gives insight into how the Universe became reionized, a problem that astronomers have been trying to solve for years.
The research is published in The Astrophysical Journal, a peer-reviewed scientific journal of astrophysics and astronomy.
After the Big Bang, when the Universe was formed billions of years ago, it was in an ionized state. This means that the electrons and protons floated freely throughout space. As the Universe expanded and started cooling down, it changed to a neutral state when the protons and electrons combined into atoms, akin to water vapor condensing into a cloud.
Now however, scientists have observed that the Universe is back in an ionized state. A major endeavor in astronomy is figuring out how this happened. Astronomers have theorized that the energy for reionization must have come from galaxies themselves. But, it's incredibly hard for enough high energy light to escape a galaxy due to hydrogen clouds within it that absorb the light, much like clouds in the Earth's atmosphere absorb sunlight on an overcast day.
Astrophysicists from the Minnesota Institute for Astrophysics in the University of Minnesota's College of Science and Engineering may have found the answer to that problem. Using data from the Gemini telescope, the researchers have observed the first ever galaxy in a "blow-away" state, meaning that the hydrogen clouds have been removed, allowing the high energy light to escape. The scientists suspect that the blow-away was caused by many supernovas, or dying stars, exploding in a short period of time.
"The star-formation can be thought of as blowing up the balloon," explained Nathan Eggen, the paper's lead author who recently received his master's degree in astrophysics from the University of Minnesota. "If, however, the star-formation was more intense, then there would be a rupture or hole made in the surface of the balloon to let out some of that energy. In the case of this galaxy, the star-formation was so powerful that the balloon was torn to pieces, completely blown-away."
The galaxy, named Pox 186, is so small that it could fit inside the Milky Way. The researchers suspect that its compact size, coupled with its large population of stars--which amount to a hundred thousand times the mass of the sun--made the blow-away possible.
The findings confirm that a blow-away is possible, furthering the idea that small galaxies were primarily responsible for the reionization of the Universe and giving more insight into how the Universe became what it is today.
"There are a lot of scenarios in science where you theorize that something should be the case, and you don't actually find it," Eggen said. "So, getting the observational confirmation that this sort of thing can happen is really important. If this one scenario is possible, then that means that there are other galaxies that also existed in blow-away states in the past. Understanding the consequences of this blow-away gives direct insight into the impacts similar blow-aways would have had during the process of reionization."
###
In addition to Eggen, the research team included Claudia Scarlata and Evan Skillman, both professors in the School of Physics and Astronomy at the University of Minnesota, and Anne Jaskot, an assistant professor of astronomy at Williams College.
The research was funded by grants from the University of Minnesota and NASA. Researchers made use of the NASA/IPAC Extragalactic Database (NED) and NASA's Astrophysical Data System.
IMAGE: THE INTERNATIONAL RESEARCH TEAM DISCOVERED THAT THE GENOME OF DINOFLAGELLATES IS ORGANIZED IN A UNIQUE WAY COMPARED TO OTHER EUKARYOTIC GENOMES. view more
The genome of single-celled plankton, known as dinoflagellates, is organized in an incredibly strange and unusual way, according to new research. The findings lay the groundwork for further investigation into these important marine organisms and dramatically expand our picture of what a eukaryotic genome can look like.
Researchers from KAUST, the U.S. and Germany have investigated the genomic organization of the coral-symbiont dinoflagellate Symbiodinium microadriaticum. The S. microadriaticum genome had already been sequenced and assembled into segments known as scaffolds but lacked a chromosome-level assembly.
The team used a technique known as Hi-C to detect interactions in the dinoflagellate's chromatin, the combination of DNA and protein that makes up a chromosome. By analyzing these interactions, they could figure out how the scaffolds were connected together into chromosomes, giving them a view into the spatial and structural organization of the genome.
A striking finding was that the genes in the genome tended to be organized in alternating unidirectional blocks. "That's really, really different to what you see in other organisms," says Octavio Salazar, a Ph.D. student in Manuel Aranda's group at KAUST and one of the lead authors of the study. The orientation of genes on a chromosome is usually random. In this case, however, genes were consistently oriented one way and then the other, with the boundaries between blocks showing up clearly in the chromatin interaction data.
"Nature can work in a completely different way than we thought."
This organization is also reflected in the three-dimensional structure of the genome, which the team inferred comprises rod-shaped chromosomes that fold into structural domains at the boundaries where gene blocks converge. Even more intriguingly, this structure appears to be dependent on transcriptional activity. When the researchers treated cells with a chemical that blocks gene transcription, the structural domains disappeared.
This unusual link is consistent with another strange fact about dinoflagellates -- they have very few transcription factors in their genome and do not seem to respond to environmental changes by altering gene expression. They may use gene dosage to control expression and adapt to the environment by losing or gaining chromosomes or perhaps via epigenetic structural modifications. The researchers plan to explore all of these questions.
Another open question is the origin of this exceptional genome structure. Dinoflagellates produce very few histones, the proteins used by other eukaryotes to structure their DNA, instead using viral proteins incorporated into their genome long ago. The extraordinary genome structure and genetic regulation may be a consequence of how these viral proteins work, but that remains to be confirmed.
The dinoflagellate genome defies the expectation and dogmas built from studying other eukaryotes. "It shows that nature can work in a completely different way than we thought," says Salazar. "There are so many possibilities for what could have happened as life evolved."
New Geology articles published online ahead of print in April
Boulder, Colo., USA: Thirty-one new articles were published online ahead of print for Geology in April. Topics include shocked zircon from the Chicxulub impact crater; the Holocene Sonoran Desert; the architecture of the Congo Basin; the southern Death Valley fault; missing water from the Qiangtang Basin; sulfide inclusions in diamonds; how Himalayan collision stems from subduction; ghost dune hollows; and the history of the Larsen C Ice Shelf.
IMAGE: ANCIENT OSTRICH EGGSHELLS FROM YSTERFONTEIN 1, A MIDDLE STONE AGE MIDDEN IN SOUTH AFRICA. SHOWN ARE SELECTED EGGSHELLS FROM THE TOP LAYER OF THE MIDDEN DATED BY URANIUM-THORIUM (U-TH, OR... view more
CREDIT: IMAGE COURTESY OF E. NIESPOLO.
Archeologists have learned a lot about our ancestors by rummaging through their garbage piles, which contain evidence of their diet and population levels as the local flora and fauna changed over time.
One common kitchen scrap in Africa -- shells of ostrich eggs -- is now helping unscramble the mystery of when these changes took place, providing a timeline for some of the earliest Homo sapiens who settled down to utilize marine food resources along the South African coast more than 100,000 years ago.
Geochronologists at the University of California, Berkeley, and the Berkeley Geochronology Center (BGC) have developed a technique that uses these ubiquitous discards to precisely date garbage dumps -- politely called middens -- that are too old to be dated by radiocarbon or carbon-14 techniques, the standard for materials like bone and wood that are younger than about 50,000 years.
In a paper published this month in the journal Proceedings of the National Academy of Sciences, former UC Berkeley doctoral student Elizabeth Niespolo and geochronologist and BGC and associate director Warren Sharp reported using uranium-thorium dating of ostrich eggshells to establish that a midden outside Cape Town, South Africa, was deposited between 119,900 and 113,100 years ago.
That makes the site, called Ysterfontein 1, the oldest known seashell midden in the world, and implies that early humans were fully adapted to coastal living by about 120,000 years ago. This also establishes that three hominid teeth found at the site are among the oldest Homo sapiens fossils recovered in southern Africa.
The technique is precise enough for the researchers to state convincingly that the 12.5-foot-deep pile of mostly marine shells -- mussels, mollusks and limpets -- intermixed with animal bones and eggshells may have been deposited over a period of as little as 2,300 years.
The new ages are already revising some of the assumptions archeologists had made about the early Homo sapiens who deposited their garbage at the site, including how their population and foraging strategies changed with changing climate and sea level.
"The reason why this is exciting is that this site wouldn't have been datable by radiocarbon because it is too old," Niespolo said, noting that there are a lot more such sites around Africa, in particular the coastal areas of South Africa.
"Almost all of this sort of site have ostrich eggshells, so now that we have this technique, there is this potential to go and revisit these sites and use this approach to date them more precisely and more accurately, and more importantly, find out if they are the same age as Ysterfontein or older or younger, and what that tells us about foraging and human behavior in the past," she added.
Because ostrich eggshells are ubiquitous in African middens -- the eggs are a rich source of protein, equivalent to about 20 chicken eggs -- they have been an attractive target for geochronologists. But applying uranium-thorium dating -- also called uranium series -- to ostrich shells has been beset by many uncertainties.
"The previous work to date eggshells with uranium series has been really hit and miss, and mostly miss," Niespolo said.
CAPTION
Eggshell structures exert a primary control on the distribution of secondary U and Th, so spatial characterization of key elements and careful sampling are required to produce accurate ages by 230Th/U dating. Scale bars are 1 mm. A. Thin section photomicrograph of a modern ostrich eggshell in cross section, and corresponding eggshell structures denoted by V (vertical layer), P (palisade or prismatic layer), and C (cone layer). Pores serving as oxygen pathways for incubating chicks are visible as open holes penetrating through the eggshell. B. Epoxy-mounted fragment of an ancient eggshell from Ysterfontein 1 in cross section, showing the same eggshell structures are well preserved in deep time. Analyses from laser ablation are evident along pitted lines and track concentrations of U and Th. A pore is apparent in the center of the mounted fragment. 230Th/U burial ages of eggshells from this layer are ~118 thousand years old.
CREDIT
Images courtesy of E. Niespolo.
Precision dating pushed back to 500,000 years ago
Other methods applicable to sites older than 50,000 years, such as luminescence dating, are less precise -- often by a factor of 3 or more -- and cannot be performed on archival materials available in museums, Sharp said.
The researchers believe that uranium-thorium dating can provide ages for ostrich eggshells as old as 500,000 years, extending precise dating of middens and other archeological sites approximately 10 times further into the past.
"This is the first published body of data that shows that we can get really coherent results for things well out of radiocarbon range, around 120,000 years ago in this case," said Sharp, who specializes in using uranium-thorium dating to solve problems in paleoclimate and tectonics as well as archeology. "It is showing that these eggshells maintain their intact uranium-series systems and give reliable ages farther back in time than had been demonstrated before."
"The new dates on ostrich eggshell and excellent faunal preservation make Ysterfontein 1 the as-yet best dated multi-stratified Middle Stone Age shell midden on the South African west coast," said co-author Graham Avery, an archeozoologist and retired researcher with the Iziko South African Museum. "Further application of the novel dating method, where ostrich eggshell fragments are available, will strengthen chronological control in nearby Middle Stone Age sites, such as Hoedjiespunt and Sea Harvest, which have similar faunal and lithic assemblages, and others on the southern Cape coast."
The first human settlements?
Ysterfontein 1 is one of about a dozen shell middens scattered along the western and eastern coasts of Western Cape Province, near Cape Town. Excavated in the early 2000s, it is considered a Middle Stone Age site established around the time that Homo sapiens were developing complex behaviors such as territoriality and intergroup competition, as well as cooperation among non-kin groups. These changes may be due to the fact that these groups were transitioning from hunter-gatherers to settled populations, thanks to stable sources of high-quality protein -- shellfish and marine mammals -- from the sea.
Until now, the ages of Middle Stone Age sites like Ysterfontein 1 have been uncertain by about 10%, making comparison among Middle Stone Age sites and with Later Stone Age sites difficult. The new dates, with a precision of about 2% to 3%, place the site in the context of well-documented changes in global climate: it was occupied immediately after the last interglacial period, when sea level was at a high, perhaps 8 meters (26 feet) higher than today. Sea level dropped rapidly during the occupation of the site -- the shoreline retreated up to 2 miles during this period -- but the accumulation of shells continued steadily, implying that the inhabitants found ways to accommodate the changing distribution of marine food resources to maintain their preferred diet.
The study also shows that the Ysterfontein 1 shell midden accumulated rapidly -- perhaps about 1 meter (3 feet) every 1,000 years --- implying that Middle Stone Age people along the southern African coast made extensive use of marine resources, much like people did during the Later Stone Age, and suggesting that effective marine foraging strategies developed early.
For dating, eggshells are better
Ages can be attached to some archeological sites older than 50,000 years through argon-argon (40Ar/39Ar) dating of volcanic ash. But ash isn't always present. In Africa, however -- and before the Holocene, throughout the Middle East and Asia -- ostrich eggshells are common. Some sites even contain ostrich eggshell ornaments made by early Homo sapiens.
Over the last four years, Sharp and Niespolo conducted a thorough study of ostrich eggshells, including analysis of modern eggshells obtained from an ostrich farm in Solvang, California, and developed a systematic way to avoid the uncertainties of earlier analyses. One key observation was that animals, including ostriches, do not take up and store uranium, even though it is common at parts-per-billion levels in most water. They demonstrated that newly laid ostrich shells contain no uranium, but that it is absorbed after burial in the ground.
The same is true of seashells, but their calcium carbonate structure -- a mineral called aragonite -- is not as stable when buried in soil as the calcite form of calcium carbonate found in eggshell. Because of this, eggshells retain better the uranium taken up during the first hundred years or so that that they are buried. Bone, consisting mostly of calcium phosphate, has a mineral structure that also does not remain stable in most soil environments nor reliably retains absorbed uranium.
Uranium is ideal for dating because it decays at a constant rate over time to an isotope of thorium that can be measured in minute amounts by mass spectrometry. The ratio of this thorium isotope to the uranium still present tells geochronologists how long the uranium has been sitting in the eggshell.
Uranium-series dating relies on uranium-238, the dominant uranium isotope in nature, which decays to thorium-230. In the protocol developed by Sharp and Niespolo, they used a laser to aerosolize small patches along a cross-section of the shell, and ran the aerosol through a mass spectrometer to determine its composition. They looked for spots high in uranium and not contaminated by a second isotope of thorium, thorium-232, which also invades eggshells after burial, though not as deeply. They collected more material from those areas, dissolved it in acid, and then analyzed it more precisely for uranium-238 and thorium-230 with "solution" mass spectrometry.
These procedures avoid some of the previous limitations of the technique, giving about the same precision as carbon-14, but over a time range that is 10 times larger.
"The key to this dating technique that we have developed that differs from previous attempts to date ostrich egg shells is the fact that we are explicitly accounting for the fact that ostrich eggshells have no primary uranium in them, so the uranium that we are using to date the eggshells actually comes from the soil pore water and the uranium is being taken up by the eggshells upon deposition," Niespolo said.
###
Working with UC Berkeley professor of integrative biology Todd Dawson, Niespolo also analyzed other isotopes in eggshells -- stable isotopes of carbon, nitrogen and oxygen -- to establish that the climate rapidly became drier and cooler over the period of occupation, consistent with known climate changes at that time.
Niespolo, now a postdoctoral fellow at the California Institute of Technology but soon to be an assistant professor at Princeton University, is working with Sharp to date middens at other sites near Ysterfontein. She also is developing the uranium-series technique to use with other types of eggs, such as those of emus in Australia and rheas in South America, as well as the eggs of now extinct flightless birds, such as the two-meter (6.6-foot) tall Genyornis, which died out some 50,000 years ago in Australia.
The work was supported by the Leakey Foundation, Ann and Gordon Getty Foundation and National Science Foundation (BCS-1727085).
