Explanation for formation of abundant features on Europa bodes well for search for extraterrestrial life

Peer-Reviewed Publication

STANFORD UNIVERSITY

 

IMAGE: THIS ARTIST’S CONCEPTION SHOWS HOW DOUBLE RIDGES ON THE SURFACE OF JUPITER’S MOON EUROPA MAY FORM OVER SHALLOW, REFREEZING WATER POCKETS WITHIN THE ICE SHELL. THIS MECHANISM IS BASED ON THE STUDY OF AN ANALOGOUS DOUBLE RIDGE FEATURE FOUND ON EARTH’S GREENLAND ICE SHEET. (IMAGE CREDIT: JUSTICE BLAINE WAINWRIGHT) view more 

CREDIT: JUSTICE BLAINE WAINWRIGHT

Europa is a prime candidate for life in our solar system, and its deep saltwater ocean has captivated scientists for decades. But it’s enclosed by an icy shell that could be miles to tens of miles thick, making sampling it a daunting prospect. Now, increasing evidence reveals the ice shell may be less of a barrier and more of a dynamic system – and site of potential habitability in its own right.

Ice-penetrating radar observations that captured the formation of a “double ridge” feature in Greenland suggest the ice shell of Europa may have an abundance of water pockets beneath similar features that are common on the surface. The findings, which appear in Nature Communications April 19, may be compelling for detecting potentially habitable environments within the exterior of the Jovian moon.

“Because it’s closer to the surface, where you get interesting chemicals from space, other moons and the volcanoes of Io, there’s a possibility that life has a shot if there are pockets of water in the shell,” said study senior author Dustin Schroeder, an associate professor of geophysics at Stanford University’s School of Earth, Energy & Environmental Sciences (Stanford Earth). “If the mechanism we see in Greenland is how these things happen on Europa, it suggests there’s water everywhere.”

A terrestrial analog

On Earth, researchers analyze polar regions using airborne geophysical instruments to understand how the growth and retreat of ice sheets might impact sea-level rise. Much of that study area occurs on land, where the flow of ice sheets is subject to complex hydrology – such as dynamic subglacial lakes, surface melt ponds and seasonal drainage conduits – that contributes to uncertainty in sea-level predictions.

Because a land-based subsurface is so different from Europa’s subsurface ocean of liquid water, the study co-authors were surprised when, during a lab group presentation about Europa, they noticed that formations that streak the icy moon looked extremely similar to a minor feature on the surface of the Greenland ice sheet – an ice sheet that the group has studied in detail.

“We were working on something totally different related to climate change and its impact on the surface of Greenland when we saw these tiny double ridges – and we were able to see the ridges go from ‘not formed’ to ‘formed,’ ” Schroeder said.

Upon further examination, they found that the “M”-shaped crest in Greenland known as a double ridge could be a miniature version of the most prominent feature on Europa.

Prominent and prevalent

Double ridges on Europa appear as dramatic gashes across the moon’s icy surface, with crests reaching nearly 1000 feet, separated by valleys about a half-mile wide. Scientists have known about the features since the moon’s surface was photographed by the Galileo spacecraft in the 1990s but have not been able to conceive a definitive explanation of how they were formed.

Through analyses of surface elevation data and ice-penetrating radar collected from 2015 to 2017 by NASA’s Operation IceBridge, the researchers revealed how the double ridge on northwest Greenland was produced when the ice fractured around a pocket of pressurized liquid water that was refreezing inside of the ice sheet, causing two peaks to rise into the distinct shape.

“In Greenland, this double ridge formed in a place where water from surface lakes and streams frequently drains into the near-surface and refreezes,” said lead study author Riley Culberg, a PhD student in electrical engineering at Stanford. “One way that similar shallow water pockets could form on Europa might be through water from the subsurface ocean being forced up into the ice shell through fractures – and that would suggest there could be a reasonable amount of exchange happening inside of the ice shell.”

Snowballing complexity

Rather than behaving like a block of inert ice, the shell of Europa seems to undergo a variety of geological and hydrological processes – an idea supported by this study and others, including evidence of water plumes that erupt to the surface. A dynamic ice shell supports habitability since it facilitates the exchange between the subsurface ocean and nutrients from neighboring celestial bodies accumulated on the surface.

“People have been studying these double ridges for over 20 years now, but this is the first time we were actually able to watch something similar on Earth and see nature work out its magic,” said study co-author Gregor Steinbrügge, a planetary scientist at NASA’s Jet Propulsion Laboratory (JPL) who started working on the project as a postdoctoral researcher at Stanford. “We are making a much bigger step into the direction of understanding what processes actually dominate the physics and the dynamics of Europa’s ice shell.”

The co-authors said their explanation for how the double ridges form is so complex, they couldn’t have conceived it without the analog on Earth.

“The mechanism we put forward in this paper would have been almost too audacious and complicated to propose without seeing it happen in Greenland,” Schroeder said.

The findings equip researchers with a radar signature for quickly detecting this process of double ridge formation using ice-penetrating radar, which is among the instruments currently planned for exploring Europa from space.

“We are another hypothesis on top of many – we just have the advantage that our hypothesis has some observations from the formation of a similar feature on Earth to back it up,” Culberg said. “It’s opening up all these new possibilities for a very exciting discovery.”

Schroeder is also a faculty affiliate with the Institute for Human-Centered Artificial Intelligence (HAI), an associate professor, by courtesy, of electrical engineering and a center fellow, by courtesy, at the Stanford Woods Institute for the Environment. 

This research was supported by a National Defense Science and Engineering Graduate Fellowship and, in part, by NASA Grant NNX16AJ95G and NSF Grant 1745137.

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JOURNAL

Nature Communications

DOI

10.1038/s41467-022-29458-3 

ARTICLE TITLE

Double ridge formation over shallow water sills on Jupiter’s moon Europa

ARTICLE PUBLICATION DATE

19-Apr-2022

New process enables 3D printing of small and complex components made of glass in just a few minutes

Scientists combine materials science invention with newly developed 3D printing technology

Peer-Reviewed Publication

UNIVERSITY OF FREIBURG

Because of its outstanding transparency as well as its stability in contact with heat or chemicals, glass is relevant for many high-tech applications. However, conventional processes for shaping glass are often tedious, energy-intensive and quickly reach their limits for small and complicated components. The Freiburg materials scientists Dr. Frederik Kotz-Helmer and Prof. Dr. Bastian E. Rapp, in cooperation with the University of California at Berkeley in the US, have developed a novel process that can be used to produce very small components from transparent glass quickly and precisely using micro 3D printing. Possible applications include components for sensors and microscopes, but also for lab-on-a-chip systems. The researchers were able to publish their results in the current issue of the renowned journal Science.

Glass powder in plastic binder

The new technology is based on so-called Glassomer materials, which Kotz-Helmer and Rapp developed at the Department of Microsystems Engineering (IMTEK) at the University of Freiburg. “Glassomer materials consist of glass powder in a special plastic binder,” says Kotz-Helmer, “allowing to process glass like a plastic.” The resulting components are then placed in a furnace, which causes the plastic to burn and the glass to be sintered, i.e. densified. “In the end, the components consist of one hundred percent highly transparent fused silica glass,” says Kotz-Helmer.

Component is created in a single step

The Freiburg scientists have now combined Glassomer materials with a new 3D printing process developed by a research team led by Prof. Dr. Hayden Taylor from the University of California, Berkeley. Conventional 3D printers print their objects layer by layer. However, in the new process, called Computed Axial Lithography (CAL), the component is created in a single step. A vessel containing liquid, light-sensitive material is exposed to two-dimensional light images of the object to be printed from many different angles. Where the images overlap and the amount of light absorbed thus locally exceeds a certain threshold, the material hardens abruptly - within a few minutes, the component is formed. The excess, still liquid material can be washed off.

Structures with the thickness of a single hair

“In principle, this process also works with Glassomer material,” says Kotz-Helmer. For this purpose, the Freiburg scientists developed a material made of glass powder and plastic that is both highly transparent and hardens quickly at a suitable threshold value. “The devil was in the chemical details here,” says the materials scientist. Previously, moreover, the CAL process had only been suitable for relatively coarse structures. By combining the materials science expertise at the University of Freiburg and the project partner Glassomer GmbH, a Freiburg spin-off, as well as the further development of the system technology at the University of California, it has now been possible to combine and improve these technologies. “For the first time, we were able to print glass with structures in the range of 50 micrometers in just a few minutes, which corresponds roughly to the thickness of a hair,” says Kotz-Helmer. “In addition, the surfaces of the components are smoother than with conventional 3D printing processes.”

Glass as a substitute for vulnerable plastic

Kotz-Helmer sees possible applications for the innovative manufacturing process, for example, in micro-optical components of sensors, virtual reality headsets and modern microscopes: "The ability to manufacture such components at high speed and with great geometric freedom will enable new functions and more cost-effective products in the future."

Microfluidic channels are also needed for so-called lab-on-a-chip systems for research and medical diagnostics. Until now, these have mostly been made of plastics, but they often cannot withstand high temperatures and aggressive chemicals. Thanks to the new process technology, complex channel systems can now be manufactured in glass, says Kotz-Helmer: "Thanks to the thermal and chemical stability of glass, many new fields of application are opening up, especially in the area of chemistry on-a-chip synthesis."

 

Original publication
J. Toombs et al. (2022): Volumetric Additive Manufacturing of Silica Glass with Microscale Computed Axial Lithography. In: Science. DOI: 10.1126/science.abm6459

 

Contact:
Dr. Frederik Kotz-Helmer
Laboratory of Process Technology
Department of Microsystems Engineering (IMTEK)
University of Freiburg
Tel.: 0761 / 203-7355
E-Mail: frederik.kotz@imtek.de

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JOURNAL

Science

DOI

10.1126/science.abm6459 

ARTICLE TITLE

Volumetric Additive Manufacturing of Silica Glass with Microscale Computed Axial Lithography

ARTICLE PUBLICATION DATE

15-Apr-2022

How to print a robot from scratch: Combining liquids, solids could lead to faster, more flexible 3D creations

Peer-Reviewed Publication

UNIVERSITY OF COLORADO AT BOULDER

Imagine a future in which you could 3D-print an entire robot or stretchy, electronic medical device with the press of a button—no tedious hours spent assembling parts by hand.

That possibility may be closer than ever thanks to a recent advancement in 3D-printing technology led by engineers at the University of Colorado Boulder. In a new study, the team lays out a strategy for using currently-available printers to create materials that meld solid and liquid components—a tricky feat if you don’t want your robot to collapse.

“I think there’s a future where we could, for example, fabricate a complete system like a robot using this process,” said Robert MacCurdy, senior author of the study and assistant professor in the Paul M. Rady Department of Mechanical Engineering.

MacCurdy, along with doctoral students Brandon Hayes and Travis Hainsworth, published their results April 14 in the journal Additive Manufacturing.

3D printers have long been the province of hobbyists and researchers working in labs. They’re pretty good at making plastic dinosaurs or individual parts for machines, such as gears or joints. But MacCurdy believes that they can do a lot more: By mixing solids and liquids, 3D printers could churn out devices that are more flexible, dynamic and potentially more useful. They include wearable electronic devices with wires made of liquid contained within solid substrates, or even models that mimic the squishiness of real human organs.  

The engineer compares the advancement to traditional printers that print in color, not just black-and-white.

“Color printers combine a small number of primary colors to create a rich range of images,” MaCurdy said. “The same is true with materials. If you have a printer that can use multiple kinds of materials, you can combine them in new ways and create a much broader range of mechanical properties.”

Empty space

To understand those properties, it helps to compare 3D printers to the normal printers in your office. Paper printers create an image by laying down liquid inks in thousands of flat pixels. Inkjet 3D printers, in contrast, use a printhead to drop tiny beads of fluid, called “voxels” (a mash-up of  “volume” and “pixel”), one on top of the other.

“Very soon after those droplets are deposited, they are exposed to a bright, ultraviolet light,” MacCurdy said. “The curable liquids convert into solids within a second or less.”

But, he added, there are many cases in which you might want those liquids to stay liquid. Some engineers, for example, use liquids or waxes to create tiny channels within their solid materials, which they then empty out at a later point. It’s a bit like how drips of water can carve out an underground cavern. 

Engineers have come up with ways to make those kinds of empty spaces in 3D-printed parts, but it usually takes a lot of time and effort to clean them. The channels also have to stay relatively simple. 

MacCurdy and his colleagues decided to find a way around those limitations—better understanding the conditions that would allow engineers to print solid and liquid materials at the same time. 

Liquid courage

The researchers first designed a series of computer simulations that probed the physics of printing different kinds of materials next to each other. One of the big problems, MacCurdy said is: How can you keep your droplets of solid materials from mixing into the liquid materials, even when the droplets of solid material are printed directly on top of the liquid droplets?

“We found that the surface tension of a liquid can be used to support solid material, but it is helpful to pick a liquid material that is more dense than the solid material—the same physics that allow oil to float on top of water,” Hayes said.

Next, the researchers experimented with a real 3D printer in the lab. They loaded the printer up with a curable polymer, or plastic (the solid), and with a standard cleaning solution (the liquid). Their creations were impressive: The group was able to 3D-print twisting loops of liquid and a complex network of channels not unlike the branching pathways in a human lung. 

“Both structures would have been nearly impossible to make through previous approaches,” Hainsworth said.

MacCurdy also recently joined a team of researchers from CU Boulder and the CU Anschutz Medical Campus who are developing ways to 3D-print realistic models of human tissue. Doctors could use these models to practice for procedures and make diagnoses. The project will employ MacCurdy’s liquid-solid approach among other tools. 

“We hope that our results will make multimaterial inkjet 3D printing using liquids and solids more accessible to researchers and enthusiasts around the world,” he said.

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DOI

10.1016/j.addma.2022.102785 

ARTICLE TITLE

Liquid-solid co-printing of multi-material 3D fluidic devices via material jetting

ARTICLE PUBLICATION DATE

14-Apr-2022

Georgia State researchers take step toward developing ‘electric eye’

Using nanotechnology, scientists have created a newly designed neuromorphic electronic device that endows microrobotics with colorful vision.

Peer-Reviewed Publication

GEORGIA STATE UNIVERSITY

 

IMAGE: WORKING PRINCIPLE AND DEVICE STRUCTURE OF THE NEW COLOR SENSOR DESIGN BY GEORGIA STATE RESEARCHERS. view more 

CREDIT: GRAPHIC IMAGE FROM RESEARCH TEAM

ATLANTA—Georgia State University researchers have successfully designed a new type of artificial vision device that incorporates a novel vertical stacking architecture and allows for greater depth of color recognition and scalability on a micro-level. The new research is published in the top journal ACS Nano.

“This work is the first step toward our final destination­–to develop a micro-scale camera for microrobots,” says assistant professor of Physics Sidong Lei, who led the research. “We illustrate the fundamental principle and feasibility to construct this new type of image sensor with emphasis on miniaturization.”

Lei’s team was able to lay the groundwork for the biomimetic artificial vision device, which uses synthetic methods to mimic biochemical processes, using na­notechnology.

“It is well-known that more than 80 percent of the information is captured by vision in research, industry, medication, and our daily life,” he says. “The ultimate purpose of our research is to develop a micro-scale camera for microrobots that can enter narrow spaces that are intangible by current means, and open up new horizons in medical diagnosis, environmental study, manufacturing, archaeology, and more.”

This biomimetic “electric eye” advances color recognition, the most critical vision function, which is missed in the current research due to the difficulty of downscaling the prevailing color sensing devices. Conventional color sensors typically adopt a lateral color sensing channel layout and consume a large amount of physical space and offer less accurate color detection.

Researchers developed the unique stacking technique which offers a novel approach to the hardware design. He says the van der Waals semiconductor-empowered vertical color sensing structure offers precise color recognition capability which can simplify the design of the optical lens system for the downscaling of the artificial vision systems.

Ningxin Li, a graduate student in Dr. Lei’s Functional Materials Studio who was part of the research team, says recent advancements in technology make the new design possible.

“The new functionality achieved in our image sensor architecture all depends on the rapid progress of van der Waals semiconductors during recent years,” says Li. “Compared with conventional semiconductors, such as silicon, we can precisely control the van der Waals material band structure, thickness, and other critical parameters to sense the red, green, and blue colors.”

The van der Waals semiconductors empowered vertical color sensor (vdW-Ss) represent a newly-emerged class of materials, in which individual atomic layers are bonded by weak van der Waals forces. They constitute one of the most prominent platforms for discovering new physics and designing next-generation devices.

“The ultra-thinness, mechanical flexibility, and chemical stability of these new semiconductor materials allow us to stack them in arbitrary orders. So, we are actually introducing a three-dimensional integration strategy in contrast to the current planar micro-electronics layout. The higher integration density is the main reason why our device architecture can accelerate the downscaling of cameras,” Li says.

The technology currently is patent pending with Georgia State’s Office of Technology Transfer & Commercialization (OTTC). OTTC anticipates this new design will be of high interest to certain industry partners. “This technology has the potential to overcome some of the key drawbacks seen with current sensors, says OTTC’s Director, Cliff Michaels. “As nanotechnology advances and devices become more compact, these smaller, highly sensitive color sensors will be incredibly useful.”

Researchers believe the discovery could even spawn advancements to help the vision-impaired one day.

“This technology is crucial for the development of biomimetic electronic eyes and also other neuromorphic prosthetic devices,” says Li. “High-quality color sensing and image recognition function may bring new possibilities of colorful item perception for the visually impaired in the future.”

Lei says his team will continue pushing these advanced technologies forward using what they’ve learned from this discovery.

“This is a great step forward, but we are still facing scientific and technical challenges ahead, for example, wafer-scale integration. Commercial image sensors can integrate millions of pixels to deliver high-definition images, but this has not been implemented in our prototype yet,” he says. “This large-scale van der Waals semiconductor device integration is currently a critical challenge to be surmounted by the entire research society. Along with our nationwide collaborators that is where our team is devoting our efforts.”

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JOURNAL

ACS Nano

DOI

10.1021/acsnano.1c09875 

ARTICLE TITLE

van der Waals semiconductor empowered vertical color sensor

ARTICLE PUBLICATION DATE

18-Apr-2022

KU study identifies most vital strategies for successfully implementing changes in industry

Effective change agents, realistic timelines key in architecture, engineering, construction improvement initiatives

Peer-Reviewed Publication

UNIVERSITY OF KANSAS

LAWRENCE — Organizations regularly need to implement change initiatives to stay current, update technology, improve efficiency, enter new markets or make other improvements. However, research has suggested that more than half of change initiatives attempted in the architecture, engineering and construction (AEC) industry fail. A new study from the University of Kansas has found that six change strategies are key to successful implementation and two of them are vital for highly successful, sustained change.

The study also found that the type of change is not as important to its success as key management strategies. In surveying AEC firms across North America about an attempted change initiative, researchers found that effective change agents and a realistic timeline for the change were the two most important factors for an initiative to be deemed very successful and to last.

In their survey, researchers asked 633 firms to describe a change initiative they had attempted to install. They then implemented a scale to determine if the effort was unsuccessful, somewhat successful or very successful. The scale evaluated if the initiative was successful by three key metrics: if it was implemented into operations, benefits achieved and long-term sustainability.

"We analyzed data from across the entire industry. With organizational change, it’s something that starts with management and reaches all levels,” said Omar Maali, a doctoral candidate in engineering at KU and the study’s lead author. “They are attempted to improve efficiency, have better outcomes or make some update to the work environment. The worst thing that could happen is you lose your investment, or people try the change and revert back to what they used to do. There are a lot of recommendations in the professional literature about how to implement change. We found six key organizational change management practices."

The six key practices authors identified, in order of importance to achieve successful implementation of change:

• Effective change agents
• Establishing a realistic timeframe for the adoption process
• Communicated benefits of the change
• Establish clear and measured benchmarks of the change process
• Senior leadership commitment
• Training resources.

Maali co-wrote the study with Nancy Kepple, associate professor of social welfare, and Brian Lines, associate professor of civil, environmental & architectural engineering, all at KU. Their work, titled “Strategies to Achieve High Adoption of Organizational Change Initiatives within the AEC Industry,” was published in the Journal of Management in Engineering, part of a special issue on rethinking the benefits of adopting digital technologies in the AEC industry.

Effective change agents are defined as those working within a company who are affected by or need to accommodate a change. Maali used an example of someone required to use a new technology or software who adopts it before a deadline, advocates for its benefits with colleagues, answers questions they may have and demonstrates the value of making the change to their peers. That importance of establishing the value of change among equals instead of through mandates from management — coupled with a realistic timeframe for making the change — were the most vital practices, according to the analysis. However, the authors said management could not only focus on those two practices and realistically expect success.

“To avoid unsuccessful change efforts, you needed to use at least five organizational change management strategies to get a return on investment and make it successful,” Maali said. “To move to very successful, it was vital to have effective change agents and a realistic timeframe.”

The one strategy that didn’t prove critical to avoiding unsuccessful change was training resources, which the authors said was surprising, as previous research has suggested otherwise, especially in adopting digital technologies. And while adopting digital technologies has been a traditionally difficult change, it was not shown to be different than other types of change initiatives in that all six strategies were necessary to make it successful.

The value of the findings lies both in the large data set with information from firms across the architecture, engineering and construction industry in different regions attempting many types of changes with varying levels of success. Understanding which management strategies are most important can help firms successfully reach their goals when implementing necessary changes. Maali said future research will further explore what constitutes a realistic timeframe, and if it is not possible to achieve one, what other factors become most important. In the meantime, better understanding how to successfully implement change initiatives can help avoid unsuccessful or unsustained efforts, a major barrier in the industry.

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JOURNAL

Journal of Management in Engineering

DOI

10.1061/(ASCE)ME.1943-5479.0001051 

METHOD OF RESEARCH

Survey

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Strategies to Achieve High Adoption of Organizational Change Initiatives within the AEC Industry

Linyi Lagerstätte: A new window on Cambrian fauna evolution

Peer-Reviewed Publication

CHINESE ACADEMY OF SCIENCES HEADQUARTERS

 

IMAGE: SPATIAL AND TEMPORAL DISTRIBUTION AND TAXONOMIC DIVERSITY OF 16 MAJOR CAMBRIAN LAGERSTÄTTEN, AND THE POSITION OF THE LINYI LAGERSTÄTTE view more 

CREDIT: NIGPAS

A research team from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS) has discovered a new middle Cambrian (5.04 mya) konservat-lagerstätte in the Zhangxia Formation in Shandong Province, North China, and named it the Linyi Lagerstätte.

The Linyi Lagerstätte provides a new window into the morphological disparity, community structure, and paleogeographic distribution of marine fauna following the Cambrian explosion.

Their findings were published in National Science Review on April 5.

The rapid appearance of major animal groups and complex marine communities during the Cambrian explosion is recorded in large part in Burgess Shale-type (BST) lagerstätten.

Nevertheless, most of the well-known Cambrian lagerstätten are restricted to a few terranes, with most of them occurring in South China or Laurentia (the core of present-day North America).

This striking geographical imbalance is particularly evident in the middle Cambrian, with the major Miaolingian lagerstätten, including the Burgess Shale in British Columbia (western Canada) and five lagerstätten in the Great Basin (western USA), being located predominantly in Laurentia. The large temporospatial discrepancy of distribution of the soft-bodied fossil lagerstätten limits our understanding of the Cambrian explosion of animals on Earth.

The limited known spatial distribution of Cambrian lagerstätten thus underscores the importance of the newly discovered Miaolingian Linyi Lagerstätte.

The new assemblage contains a variety of well-preserved soft-bodied fossils, among which the non-trilobite arthropods, particularly the mollisoniids and radiodonts, are the most important groups. The Linyi Lagerstätte is remarkable for its excellent preservation of arthropod limbs, eyes, and guts, with these well-preserved fossils promising to yield new anatomical data bearing on the early evolution of animals.

"The close similarity in taxonomy between the Linyi Lagerstätte of North China and those of Laurentian lagerstätten suggests that North China may have provided a biogeographic link between East Gondwana and Laurentia," said Prof. ZHAO Fangchen, corresponding author of the study.

North China is now an important region for investigating the early evolution of middle Cambrian animals, and its Miaolingian deposits have great potential for yielding additional exceptional biotas.

Since the discovery of the Chengjiang Biota in 1984, South China has gradually become the principal area for the study of early Cambrian lagerstätte. The discovery of the Linyi Lagerstätte may also open a new chapter in the study of middle Cambrian BST deposits in North China.

CAPTION

Representative fossils from the Linyi Lagerstätte

CREDIT

NIGPAS

CAPTION

Life on the platform margin of the Miaolingian Sea, North China, based on data from the Linyi Lagerstätte

CREDIT

YANG Dinghua

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JOURNAL

National Science Review

DOI

10.1093/nsr/nwac069 

ARTICLE TITLE

The middle Cambrian Linyi Lagerstätte from the North China Craton: a new window on the Cambrian evolutionary fauna

Extreme genetic drift in the Maniq hunter-gatherers of southern Thailand

Peer-Reviewed Publication

SMBE JOURNALS (MOLECULAR BIOLOGY AND EVOLUTION AND GENOME BIOLOGY AND EVOLUTION)

 

IMAGE: MAP WITH APPROXIMATE LOCATIONS OF THE MANIQ AND OTHER NEARBY POPULATIONS INCLUDED IN THE STUDY. view more 

CREDIT: TOBIAS GÖLLNER

Residing in the hills of southern Thailand, the Maniq comprise one of the last hunter-gatherer communities in the world. Although the Maniq are geographically isolated, they share many cultural features with the Semang peoples, most of whom live over the border in Malaysia. Due to the complex relationships among the various communities in mainland Southeast Asia, anthropologists have long debated the demographic history of the area, with one, two, three, or four waves of human migration having been proposed for the region. A recent study in Genome Biology and Evolution by Tobias Göllner, Maximilian Larena, and colleagues titled “Unveiling the genetic history of the Maniq, a primary hunter-gatherer society” provides new insight into the Maniq and their relationships with other indigenous groups in mainland Southeast Asia.

The international team of researchers from the University of Vienna in Austria, Uppsala University in Sweden, and Khon Kaen University in Thailand studied 2.3 million single-nucleotide polymorphisms (SNPs) in 11 Maniq individuals who agreed to participate in the study. While a relatively small sample, this represents over 3% of the current Maniq population of ~250 individuals. The team then compared the data from the Maniq with both present-day populations and ancient DNA samples collected in the region.

“One of our main conclusions is that the Maniq are a very secluded community and have been separated from the other Semang for quite some time,” says Göllner, first author of the study. As suggested by their cultural ties, the Maniq appeared to be most closely related to the Semang groups in Malaysia, indicating a recent shared history. Comparisons with other modern groups showed that the Maniq and Malay Semang populations shared alleles with indigenous Papuans and Andamanese, indicating “deep historical relationships among these populations,” according to the study’s authors.

The study also revealed that the Maniq exhibited similarities to ancient DNA samples associated with the Hòabìnhian, a cultural complex of ancient hunter-gatherers thought to be the ancestors of present-day hunter-gatherers in mainland Southeast Asia. In the past, Hòabìnhian-related populations were more widespread, with descendants found in Laos, southern China, and even as far as Japan. According to the study’s authors, however, “due to the recent expansion of East Asian-related groups, the Hòabìnhian-related cultural communities were either displaced, replaced, or absorbed into the larger population of farmer migrants.” The study reveals that this was not the case with the Maniq, who remained largely isolated and retained their hunter-gatherer lifestyle, “making them one of the few groups in mainland Asia carrying high levels of Hòabìnhian-related ancestry.”

The study did find evidence for some East Asian ancestry among the Maniq. “The most plausible model for the ancestral source of the Maniq is a combination of both Andamanese and East Asian-related ancestries,” posit the authors, with relative contributions of roughly 65% and 35%, respectively. The researchers estimated that this East Asian ancestry was introduced into the Maniq population approximately 700 years ago, likely via their Malay Semang neighbors.

The most striking finding of the study was the high degree of genetic differentiation exhibited by the Maniq, which was higher than what has been observed for the Mangyan Buhid of the Philippines and comparable to that of the Surui of Brazil, suggesting that the Maniq are more genetically differentiated than virtually any other known human population worldwide. This is likely due to a combination of genetic drift, a long history of geographic and cultural isolation, their historically small population size, and their cultural practice of marrying largely within their own society.

To validate these findings, Göllner hopes to conduct additional studies with larger sample sizes or full genome sequencing data. He notes that the current study and any future work “is only possible thanks to the participation of the Maniq and their long-standing relationship with our cultural anthropologist, Helmut Lukas.” Such studies are made more difficult however by the fact that the Maniq currently face several challenges, including intrusion from outsiders, ethnic discrimination, and most notably, the deforestation of the rainforest, limiting their ability to hunt, gather, and follow a traditional lifestyle. Says Göllner, “While solutions will have to be led by the Maniq and other citizens of Thailand, we hope that highlighting the importance of the Maniq will inspire change and help to protect their way of life.”

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JOURNAL

Genome Biology and Evolution

DOI

10.1093/gbe/evac021 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Unveiling the genetic history of the Maniq, a primary hunter-gatherer society

Record low Antarctic sea-ice extent since the satellite era

The new record shows for the first time the sea-ice extent shrank to below 2 million km2

Peer-Reviewed Publication

INSTITUTE OF ATMOSPHERIC PHYSICS, CHINESE ACADEMY OF SCIENCES

 

IMAGE: ON 25 FEBRUARY 2022, SCIENTISTS RECORDED NEAR-RECORD BELOW NORMAL SEA ICE EXTENT IN THE ANTARCTIC. THE COVER PHOTO OF SEA ICE (CREDIT: YINGQI LIANG) WAS TAKEN ON 30 JANUARY 2022 ONBOARD XUELONG2 IN THE ANTARCTIC COSMONAUTS SEA. view more 

CREDIT: ADVANCES IN ATMOSPHERIC SCIENCES

Arctic sea ice may be disappearing, but until recently Antarctic sea ice was having the opposite experience. In February however, the extent of sea ice at the southern hemisphere experienced a record low, the second such event in five years. Researchers have now identified its proximate causes, but many mysteries remain.

A study describing their findings was published in the journal Advances in Atmospheric Sciences on April 19.

The extent of sea ice in the Arctic is famously undergoing rapid decline as a result of global warming, but at the Earth’s other pole, Antarctic sea ice has been enjoying a modest increasing trend of about one percent a decade since the late 1970s (albeit with significant variation from year to year and substantial regional differences).

Yet in the face of this overall increasing trend in the Antarctic, there was something of a brief but quite marked aberration in 2017, when the southern hemisphere experienced a record minimum extent of sea ice.

And now just five years later, it has happened again.

On February 25 2022, a few days from the end of the Southern hemisphere’s summer, a record minimum in Antarctic sea ice extent was set—the first time it has hit under 2 million square kilometres since launch of satellite observations of the poles in 1978. The data showed that there was significantly lower than normal ice cover in the Bellingshausen/Amundsen Seas, the Weddell Sea and the western Indian Ocean sector. More curious still, throughout the region, the sea ice extent was some 30 percent lower than the average across the 1981-2010 three-decade baseline period.

The causes of the variability of Antarctic sea ice are complicated, and various mechanisms have been proposed in recent years, but there is no scientific consensus and the phenomenon remains under-theorized, with a great deal yet to be explored. And so the fresh occurrence of a fresh sea-ice extent minimum in such a short period of time drove a group of researchers at Sun Yat-sen University and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai) in China set out to find out what had occurred and why.

The team used a sea-ice budget analysis employing data on daily sea ice concentration (the percent of an area that is covered by sea ice) from 1979-2022 and daily and weekly sea-ice drift from 1979-2022 from the National Snow and Ice Data Center (NSIDC) to develop their understanding. A sea-ice budget analysis involves a consideration of the number of inputs versus outputs of the sea-ice system, in other words, the sea ice that was added and that which was lost, alongside both the dynamics (including advection and divergence contributions) and the thermodynamics (processes concerning freezing and melting) that affect this. The sea-ice budget analysis was carried out to cover the melting seasons and then connect this to atmospheric circulation over the same periods.

The researchers found that in the summertime, it is the thermodynamics that dominate the processes that cause the sea ice melting. This occurs through anomalies in the transport of heat toward the pole in the Bellingshausen/Amundsen Seas, the western Pacific Ocean, and the eastern Weddell Sea in particular.

There is also an increase in overall infrared radiation and visible light as a result of a positive feedback of albedo and temperature. Albedo describes basically the ‘whiteness’ of a surface. The whiter it is, the greater the reflection of such radiation, and the darker, the greater the absorption.

“Sea ice is whiter than the dark unfrozen sea, thus there is less reflection of heat and more absorption,” said climatologist Qinghua Yang, a co-author of the study. “which in turn melts more sea ice, producing more absorption of heat, in a vicious cycle.”

But in the spring, both thermodynamics and dynamics contribute to the status of sea ice extent. In addition to the above thermodynamic processes, the dynamics of ice loss in the Amundsen Sea sees a northward ice motion that pushes more ice to the lower latitudes towards the tropics thus increasing melting, especially in the Amundsen Sea and the Ross Sea. In addition, thinner sea ice freeboard (the thickness of the sea ice that sticks out above the waterline) along the coast of the Amundsen Sea plays a critical role with respect to the spring and summer melting.

The researchers noted that according to data from the US National Oceanographic and Atmospheric Administration (NOAA), the new record Antarctic sea-ice extent minimum occurred at the same time as a combination of La Niña and a positive Southern Annular Mode (SAM). The SAM describes a belt of strong westerly winds or low pressure that surrounds the continent, moving north or south, while La Niña describes a weather pattern of powerful winds that blow warm ocean surface water strong from South America to Indonesia in the tropics.

Both of these phenomena deepen the Amundsen Sea low (ASL)—a center of low atmospheric pressure center over the far south of the Pacific Ocean and off the coast of West Antarctica. The variability of atmospheric conditions in the region is greater than anywhere else in the Southern Hemisphere.

The researchers found that all the atmospheric impacts on the sea-ice extent anomalies originate with the intensity and position of the Amundsen Sea low.

The researchers were able to explain much, but their findings only produced further questions.

“If tropical variability is having such an impact, it’s that location that needs to be studied next,” said Jinfei Wang, one of the other authors of the paper.

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DOI

10.1007/s00376-022-2087-1 

ARTICLE TITLE

An Unprecedented Record Low Antarctic Sea-ice Extent during Austral Summer 2022

ARTICLE PUBLICATION DATE

19-Apr-2022