Monday, September 30, 2019

Did Mosasaurs Do the Breast Stroke?

Mosasaurs were true sea monsters of late Cretaceous seas. These marine lizards—related to modern snakes and monitor lizards—grew as long as fifty feet, flashed two rows of sharp teeth, and shredded their victims with enormous, powerful jaws.

Now, new research suggests that mosasaurs had yet another potent advantage: a muscular breast stroke that may have added ambush-worthy bursts of speed.

“We know that mosasaurs most likely used their tails for locomotion. Now we think that they also used their forelimbs, or their tail and forelimbs together,” explains lead author Kiersten Formoso, a Ph.D. student in vertebrate paleontology at the University of Southern California. That dual swimming style, she says, could make mosasaurs unique among tetrapods (four limbed creatures), living or extinct.

Plotosaurus bennisoni is a mosasaur from the Upper Cretaceous (Maastrichtian) North America. Restoration
 Illustration from Wikimedia Commons,

Previous studies noted that mosasaurs had an unusually large pectoral girdle—the suite of bones that support the forelimbs. But most assumed the creature’s swimming was mainly driven by their long tails, something like alligators or whales. That smooth, long distance-adapted swimming style is called “cruising,” as opposed to “burst” motion. “Like anything that swims or flies, the laws of fluid dynamics mean that burst versus cruising is a tradeoff,” explains co-author Mike Habib, Assistant Professor of Anatomical Sciences at USC. “Not many animals are good at both.”

To dive in more closely on whether mosasaurs were burst-adapted, cruise-adapted, or an unusual balance of both, Formoso and co-authors focused on the oversized pectoral girdle. They studied a fossil Plotosaurus, a type of mosasaur, at the Natural History Museum of Los Angeles County. In addition, they used measurements of mosasaur pectoral girdles published in other studies.

They determined that the mosasaurs’ unusually large and low-placed pectoral girdle supported large muscle attachments. In addition, says Habib, asymmetry in the bone structure is a telltale sign of the strong, inward pull-down motion called adduction. These analyses suggest that mosasaurs used their forelimbs to swim, breast-stroke style, adding powerful bursts of propulsion to their ability to cruise.

The team continues to model bone structure, morphology, measurements, and fluid dynamics such as drag to learn exactly how, and how fast, these sea monsters swam. Along with applications to biomechanics, and even robotics, say Formoso and Habib, the study also sheds light on how evolution and ecosystems are affected by fluid dynamics.

Formoso points out that it’s a challenge to study kinematics on extinct animals, considering that the subjects are missing flesh, skin, and many bones. But one thing is nearly certain, she says. “Mosasaurs swam unlike anything else.”

Contacts and sources:
Christa Stratton, Geological Society of America
Kiersten Formoso, USC Department of Earth Sciences

Presentation: Reassessment of the Mosasaur Pectoral Girdle and its Role in Aquatic Locomotion
Tuesday, 24 Sept., 8:30 a.m., Room 225AB, Phoenix Convention Center North Building

Type 2 Diabetes Remission Possible with ‘Achievable’ Weight Loss, Say Researchers

People who achieve weight loss of 10% or more in the first five years following diagnosis with type 2 diabetes have the greatest chance of seeing their disease go into remission, according to a study led by the University of Cambridge.

Credit: zuzyusa

The findings suggest that it is possible to recover from the disease without intensive lifestyle interventions or extreme calorie restrictions.

Type 2 diabetes affects 400 million people worldwide and increases the risk of heart disease, stroke, blindness and amputations. While the disease can be managed through a combination of positive lifestyle changes and medication, it is also possible for the high blood glucose levels that define diabetes to return to normal – through significant calorie restriction and weight loss. An intensive low-calorie diet involving a total daily intake of 700 calories (less than one cheeseburger) for 8 weeks has been associated with remission in almost nine out of ten people with recently diagnosed diabetes and in a half of people with longstanding disease.

However, there is little evidence to show whether the same effect can be achieved by people undergoing less intensive interventions, which are more feasible and potentially scalable to the wider population. To answer this question, a team led by researchers at the University of Cambridge studied data from the ADDITION-Cambridge trial, a prospective cohort study of 867 people with newly diagnosed diabetes aged 40 and 69 years recruited from general practices in the eastern region.

The research was funded by Wellcome, the Medical Research Council and the National Institute for Health Research.

The researchers found that 257 participants (30%) participants were in remission at five-year follow-up. People who achieved weight loss of 10% or more within the first five years after diagnosis were more than twice as likely to go into remission compared to people who maintained the same weight.

“We’ve known for some time now that it’s possible to send diabetes into remission using fairly drastic measures such as intensive weight loss programmes and extreme calorie restriction,” says Dr Hajira Dambha-Miller from the Department of Public Health and Primary Care.

“These interventions can be very challenging to individuals and difficult to achieve. But, our results suggest that it may be possible to get rid of diabetes, for at least five years, with a more modest weight loss of 10%. This will be more motivating and hence more achievable for many people.”

Senior author Professor Simon Griffin of the MRC Epidemiology Unit added: “This reinforces the importance of managing one’s weight, which can be achieved through changes in diet and increasing physical activity. Type 2 diabetes, while a chronic disease, can lead to significant complications, but as our study shows, can be controlled and even reversed.”

In order to clarify the best way to help patients with type 2 diabetes achieve sustained weight loss, the team is currently undertaking a study called GLoW (Glucose Lowering through Weight management). The study compares the current education programme offered by the NHS to people after they have been diagnosed, with a programme delivered by WW (formerly Weight Watchers®). The team is looking to recruit individuals who have been diagnosed with type 2 diabetes within the last three years, have not attended a structured education programme and are able to visit one of our testing centres in Wisbech, Ely or Addenbrooke’s Hospital. Further details can be found at the GLOW Study website.

Contacts and sources:
Craig BrierleyUniversity of Cambridge.

Citation: Behaviour change, weight loss and remission of Type 2 diabetes: a community‐based prospective cohort study H. Dambha‐Miller A. J. Day J. Strelitz G. Irving S. J. Griffin

Otherworldly Worms with Three Sexes Discovered in Mono Lake

Caltech scientists have discovered a new species of worm thriving in the extreme environment of Mono Lake. This new species, temporarily dubbed Auanema sp., has three different sexes, can survive 500 times the lethal human dose of arsenic, and carries its young inside its body like a kangaroo.

Mono Lake, located in the Eastern Sierras of California, is three times as salty as the ocean and has an alkaline pH of 10. Before this study, only two other species (other than bacteria and algae) were known to live in the lake—brine shrimp and diving flies. In this new work, the team discovered eight more species, all belonging to a class of microscopic worms called nematodes, thriving in and around Mono Lake.

Auanema sp., a newly discovered nematode species in Mono Lake, is considered an extremophile for its ability to thrive under harsh conditions.
An image of a worm
Credit: Caltech

The work was done primarily in the laboratory of Paul Sternberg, Bren Professor of Biology. A paper describing the research appears online on September 26 in the journal Current Biology.

The Sternberg laboratory has had a long interest in nematodes, particularly Caenorhabditis elegans, which uses only 300 neurons to exhibit complex behaviors, such as sleeping, learning, smelling, and moving. That simplicity makes it a useful model organism with which to study fundamental neuroscience questions. Importantly, C. elegans can easily thrive in the laboratory under normal room temperatures and pressures.

As nematodes are considered the most abundant type of animal on the planet, former Sternberg lab graduate students Pei-Yin Shih (PhD '19) and James Siho Lee (PhD '19) thought they might find them in the harsh environment of Mono Lake. The eight species they found are diverse, ranging from benign microbe-grazers to parasites and predators. Importantly, all are resilient to the arsenic-laden conditions in the lake and are thus considered extremophiles—organisms that thrive in conditions unsuitable for most life forms.

Eight different species of nematode found in and around Mono Lake, bringing the lake's total animal species (not bacteria or algae) count up to 10

.Credit: Caltech

The new worm exists in three different sexes: hermaphrodites, females, and males. The hermaphrodites can produce offspring by themselves, but the females and males need to mate in order to produce their young. The females and males are often produced early in the reproductive cycle of the mother, followed by the hermaphrodites.

"One potential explanation for this three-sex life cycle is that the females and males could help maintain genetic diversity through sexual recombination, while the hermaphrodites could disperse into new environments and establish new populations there—since they can grow a population by themselves," says Lee.

When comparing the new Auanema species to sister species in the same genus, the researchers found that the similar species also demonstrated high arsenic resistance, even though they do not live in environments with high arsenic levels. In another surprising discovery, Auanema sp. itself was found to be able to thrive in the laboratory under normal, non-extreme conditions. Only a few known extremophiles in the world can be studied in a laboratory setting.

This suggests that nematodes may have a genetic predisposition for resiliency and flexibility in adapting to harsh and benign environments alike.

"Extremophiles can teach us so much about innovative strategies for dealing with stress," says Shih. "Our study shows we still have much to learn about how these 1000-celled animals have mastered survival in extreme environments."

The researchers plan to determine if there are particular biochemical and genetic factors that enable nematodes' success and to sequence the genome of Auanema sp. to look for genes that may enable arsenic resistance. Arsenic-contaminated drinking water is a major global health concern; understanding how eukaryotes like nematodes deal with arsenic will help answer questions about how the toxin moves through and affects cells and bodies.

Researchers examine nematodes by Mono Lake in the Eastern Sierras of California.
Researchers examine nematodes by Mono Lake in the Eastern Sierras of California.
Credit: Caltech

But beyond human health, studying extreme species like the nematodes of Mono Lake contributes to a bigger, global picture of the planet, says Lee.

"It's tremendously important that we appreciate and develop a curiosity for biodiversity," he adds, noting that the team had to receive special permits for their field work at the lake. "The next innovation for biotechnology could be out there in the wild. A new biodegradable sunscreen, for example, was discovered from extremophilic bacteria and algae. We have to protect and responsibly utilize wildlife."

The paper is titled, "Newly Identified Nematodes from Mono Lake Exhibit Extreme Arsenic Resistance." Shih and Lee are co-first authors on the study; Shih is now a postdoctoral fellow at Columbia University and Lee is now a postdoctoral fellow at The Rockefeller University. In addition to Shih, Lee, and Sternberg, other co-authors are Ryoji Shinya of Meiji University in Japan, Natsumi Kanzaki of the Kansai Research Center in Japan, Andre Pires da Silva of the University of Warwick in the UK, former Caltech Summer Undergraduate Research Fellow student Jean Marie Badroos now of UC Berkeley, and Elizabeth Goetz and Amir Sapir of the University of Haifa in Israel. Funding was provided by the Amgen Scholars Program, the Leverhulme Trust, and the Howard Hughes Medical Institute.

Contacts and sources:
Lori Dajose

Wednesday, September 25, 2019

Electric Tech Could Reverse Baldness

ew things on earth strike fear into the hearts of men more profoundly than hair loss. But reversing baldness could someday be as easy as wearing a hat, thanks to a noninvasive, low-cost hair-growth-stimulating technology developed by engineers at the University of Wisconsin–Madison.

“I think this will be a very practical solution to hair regeneration,” says Xudong Wang, a professor of materials science and engineering at UW–Madison.

UW–Madison Materials Science and Engineering Professor Xudong Wang (left) and colleagues developed an device — unobtrusive enough to fit under a cap — that harnesses energy from the wearer and delivers gentle electric pulses to stimulate dormant hair follicles and regrow hair.
Photo: A man tries on a cap with a device in it, as another man helps.
 Credit: UW-Madison, photo by Alex Holloway  

Wang and colleagues published a description of the technology in the journal ACS Nano.

Based on devices that gather energy from a body’s day-to-day motion, the hair-growth technology stimulates the skin with gentle, low-frequency electric pulses, which coax dormant follicles to reactivate hair production.

The devices don’t cause hair follicles to sprout anew in smooth skin. Instead they reactivate hair-producing structures that have gone dormant. That means they could be used as an intervention for people in the early stages of pattern baldness, but they wouldn’t bestow cascading tresses to someone who has been as bald as a billiard ball for several years.

Because the devices are powered by the movement of the wearer, they don’t require a bulky battery pack or complicated electronics. In fact, they’re so low-profile that they could be discreetly worn underneath the crown of an everyday baseball cap.

The device, right, is shown along with a baseball cap used to cover it.

 Credit: UW-Madison, photo by Alex Holloway 

Wang is a world expert in the design and creation of energy-harvesting devices. He has pioneered electric bandages that stimulate wound-healing and a weight-loss implant that uses gentle electricity to trick the stomach into feeling full.

The hair-growth technology is based on a similar premise: Small devices called nanogenerators passively gather energy from day-to-day movements and then transmit low-frequency pulses of electricity to the skin. That gentle electric stimulation causes dormant follicles to “wake up.”

“Electric stimulations can help many different body functions,” says Wang. “But before our work there was no really good solution for low-profile devices that provide gentle but effective stimulations.”

Because the electric pulses are incredibly gentle and don’t penetrate any deeper than the very outermost layers of the scalp, the devices don’t seem to cause any unpleasant side effects. That’s a marked advantage over other baldness treatments, like the medicine Propecia, which carries risks of sexual dysfunction, depression and anxiety.

What’s more, in side-by-side tests on hairless mice, the devices stimulated hair growth just as effectively as two different compounds found in baldness medicines.

“It’s a self-activated system, very simple and easy to use,” says Wang. “The energy is very low so it will cause minimal side effects.”

The researchers have patented the concept with the Wisconsin Alumni Research Foundation, and they hope to move forward with human testing soon.

Contacts and sources:
Sam Million-Weaver
University of Wisconsin-Madison

Citation: . Self-Activated Electrical Stimulation for Effective Hair Regeneration via a Wearable Omnidirectional Pulse Generator. Guang Yao, Dawei Jiang, Jun Li, Lei Kang, Sihong Chen, Yin Long, Yizhan Wang, Peng Huang, Yuan Lin, Weibo Cai, Xudong WangACS Nano, 2019; DOI: 10.1021/acsnano.9b03912

Drinking Tea May Improve Brain Health

A recent study led by Assistant Professor Feng Lei from the NUS Yong Loo Lin School of Medicine’s Department of Psychological Medicine revealed that regular tea drinkers have better organised brain regions – and this is associated with healthy cognitive function – compared to non-tea drinkers. The research team made this discovery after examining neuroimaging data of 36 older adults.

“Our results offer the first evidence of positive contribution of tea drinking to brain structure, and suggest that drinking tea regularly has a protective effect against age-related decline in brain organisation,” explained Asst Prof Feng Lei. 

According to a study led by Asst Prof Feng Lei, drinking tea at least four times a week can improve brain efficiency
Credit: NUS

The research was carried out with collaborators from the University of Essex and University of Cambridge, and the findings were published in scientific journal Aging on 14 June 2019.

Benefits of regular intake of tea

Past studies have demonstrated that tea intake is beneficial to human health, and the positive effects include mood improvement and cardiovascular disease prevention. In fact, results of a longitudinal study led by Asst Prof Feng which was published in 2017 showed that daily consumption of tea can reduce the risk of cognitive decline in older persons by 50 per cent.

Following this discovery, Asst Prof Feng and his team further explored the direct effect of tea on brain networks.

The research team recruited 36 adults aged 60 and above, and gathered data about their health, lifestyle, and psychological well-being. The elderly participants also had to undergo neuropsychological tests and magnetic resonance imaging (MRI). The study was carried out from 2015 to 2018.

Upon analysing the participants’ cognitive performance and imaging results, the research team found that individuals who consumed either green tea, oolong tea, or black tea at least four times a week for about 25 years had brain regions that were interconnected in a more efficient way.

“Take the analogy of road traffic as an example - consider brain regions as destinations, while the connections between brain regions are roads. When a road system is better organised, the movement of vehicles and passengers is more efficient and uses less resources. Similarly, when the connections between brain regions are more structured, information processing can be performed more efficiently,” explained Asst Prof Feng.

He added, “We have shown in our previous studies that tea drinkers had better cognitive function as compared to non-tea drinkers. Our current results relating to brain network indirectly support our previous findings by showing that the positive effects of regular tea drinking are the result of improved brain organisation brought about by preventing disruption to interregional connections.”

Next step in research

As cognitive performance and brain organisation are intricately related, more research is needed to better understand how functions like memory emerge from brain circuits, and the possible interventions to better preserve cognition during the ageing process. Asst Prof Feng and his team plan to examine the effects of tea as well as the bioactive compounds in tea can have on cognitive decline.

Contacts and sources:
National University of Singapor

Citation: Habitual tea drinking modulates brain efficiency: evidence from brain connectivity evaluation. Aging, Junhua Li, Rafael Romero-Garcia, John Suckling, Lei Feng.  2019; 11 (11): 3876 DOI: 10.18632/aging.102023

Atlantic Ocean May Get a Jump Start from the Indian Ocean

A key question for climate scientists in recent years has been whether the Atlantic Ocean’s main circulation system is slowing down, a development that could have dramatic consequences for Europe and other parts of the Atlantic rim. But a new study suggests help may be on the way from an unexpected source — the Indian Ocean.

Think of it as ocean-to-ocean altruism in the age of climate change.

The new study, from Shineng Hu of the Scripps Institution of Oceanography at the University of California-San Diego and Alexey Fedorov of Yale University, appears Sept. 16 in the journal Nature Climate Change. It is the latest in a growing body of research that explores how global warming may alter global climate components such as the Atlantic meridional overturning circulation (AMOC).

Ocean  currents
Credit: NASA

AMOC is one of the planet’s largest water circulation systems. It operates like a liquid escalator, delivering warm water to the North Atlantic via an upper limb and sending colder water south via a deeper limb.

Although AMOC has been stable for thousands of years, data from the past 15 years, as well as computer model projections, have given some scientists cause for concern. AMOC has showed signs of slowing during that period, but whether it is a result of global warming or only a short-term anomaly related to natural ocean variability is not known.

“There is no consensus yet,” Fedorov said, “but I think the issue of AMOC stability should not be ignored. The mere possibility that the AMOC could collapse should be a strong reason for concern in an era when human activity is forcing significant changes to the Earth’s systems.

We know that the last time AMOC weakened substantially was 15,000 to 17,000 years ago, and it had global impacts,” Fedorov added. “We would be talking about harsh winters in Europe, with more storms or a drier Sahel in Africa due to the downward shift of the tropical rain belt, for example.”

Much of Fedorov and Hu’s work focuses on specific climate mechanisms and features that may be shifting due to global warming. Using a combination of observational data and sophisticated computer modeling, they plot out what effect such shifts might have over time. For example, Fedorov has looked previously at the role melting Arctic sea ice might have on AMOC.

For the new study, they looked at warming in the Indian Ocean.

“The Indian Ocean is one of the fingerprints of global warming,” said Hu, who is first author of the new work. “Warming of the Indian Ocean is considered one of the most robust aspects of global warming.”

The researchers said their modeling indicates a series of cascading effects that stretch from the Indian Ocean all way over to the Atlantic: As the Indian Ocean warms faster and faster, it generates additional precipitation. This, in turn, draws more air from other parts of the world to the Indian Ocean, including the Atlantic.

This world map shows the five oceanic gyres and how they impact ocean circulation. 
a world map showing the five oceanic gyres and how they impact ocean circulation
Credit: NOAA

With so much precipitation in the Indian Ocean, there will be less precipitation in the Atlantic Ocean, the researchers said. Less precipitation will lead to higher salinity in the waters of the tropical portion of the Atlantic — because there won’t be as much rainwater to dilute it. This saltier water in the Atlantic, as it comes north via AMOC, will get cold much quicker than usual and sink faster.

“This would act as a jump start for AMOC, intensifying the circulation,” Fedorov said. “On the other hand, we don’t know how long this enhanced Indian Ocean warming will continue. If other tropical oceans’ warming, especially the Pacific, catches up with the Indian Ocean, the advantage for AMOC will stop.”

The researchers said this latest finding exemplifies the intricate, interconnected nature of global climate. As scientists try to understand the unfolding effects of climate change, they must attempt to identify all of the climate variables and mechanisms that are likely to play a role.

“There are undoubtedly many other connections that we don’t know about yet,” Fedorov said. “Which mechanisms are most dominant? We’re interested in that interplay.”

The National Science Foundation, the ARCHANGE project of the Make Our Planet Great Again initiative in France, the Guggenheim fellowship, and the Scripps Institution postdoctoral fellowship helped to support the research.

Contacts and sources:
Jim Shelton
Yale University

Bird Droppings Defy Expectations

For every question about bird poop, uric acid appears to be the answer.

Why are bird droppings so hard to remove from buildings? Uric acid.

Why are they white and pasty? Uric acid.

Why are they corrosive to car paint and metal structures? Uric acid.

These answers are based on the prevailing wisdom that ranks uric acid as the primary ingredient in bird “poop,” which is comprised mostly of urine. (Birds release both solid and liquid waste at the same time. The white substance is the urine).

The ostrich was one of the six different bird species examined in the study. 
33482797 24dd635c05 K
Credit: Andrew Magill

But according to Nick Crouch, a scientist at The University of Texas at Austin, uric acid can’t be the answer. That’s because there is no uric acid in excreted bird urine.

And after analyzing the excretions from six different bird species – from the Great Horned Owl to the humble chicken – he’s pretty positive of that statement.

“It was easy to tell that what we had and that it was not uric acid,” Crouch said.

The results were published in the Journal of Ornithology in August 2019. The study’s co-authors are Julia Clarke, a professor at the Jackson School of Geosciences, where Crouch is currently a postdoctoral researcher, and Vincent Lynch a chemist and research scientist at the UT College of Natural Science.

Crouch studies bird evolution and biodiversity – the chemistry of bird waste is not his usual research wheelhouse. However, Crouch decided to investigate the uric acid question after a conversation in 2018 with the late Jackson School Professor Bob Folk, who claimed that bird waste didn’t contain uric acid.

“Sometimes you just get presented with a really weird question and you want to know the answer,” Crouch said. “That was this – I had no idea if [Folk] was right or wrong beforehand, but I was really interested to have a look.”

Folk had looked into the question himself in the 1960s and found no sign of the substance in samples collected in 17 species.

“Bob folk was a creative and boundary pushing scientist who primarily was interested in rocks,” Clarke said. “It is a testament to his limitless creativity that he took on what he referred to as his ‘bird paper’”

Folk published a paper in 1969 describing the X-ray diffraction workup and solubility tests that comprised his analysis. But his work was challenged by a 1971 paper that found evidence for uric acid in waste from Budgies, a type of parrot, using the same sort of X-ray diffraction analysis used by Folk.

Crouch said that he thought that running the analyses again using modern technology could help settle the question. Although X-ray diffraction hasn’t changed much over the past 50 years, the technology for analyzing its results – which consist of distinctive scattering patterns created when X-rays are deflected by different chemicals present in a substance – has become much more accurate and accessible over the decades.

A sample from the study undergoing X-ray diffraction. The chemical makeup of the sample is determined by interpreting the distinct deflection patterns of the X-rays. 
Credit: Nick Crouch.

As for the samples themselves, most came fresh from birds kept at the Austin Zoo, while the chicken waste sample came from a backyard flock owned by Crouch’s neighbors. All together, the samples covered a good swath of bird diversity – including species from the three major groupings of birds, a variety of diets and flightless species. But none of the samples produced an X-ray diffraction pattern consistent with uric acid. The analysis found ammonium urate, struvite and two unknown compounds.

Based on findings from other research, Crouch said that the substances are probably the result of bacteria inside the bird’s gut breaking down uric acid before it is excreted. Research conducted by other scientists having identified a diverse array of bacteria inside the digestive organs of birds that do just that.

Sushma Reddy, an associate professor and the Breckenridge Chair of Ornithology at the University of Minnesota, said she was surprised by the research findings and thinks they will spur more research into bird physiology.

“It goes against the old doctrine that we learn,” Reddy said. “It’s pretty incredible that we live in this time where we can reanalyze with incredible technologies these things that we took for granted.”

Crouch said that this research opens the door to new research questions, from the power of the bird microbiome to identifying the two unknown substances. He said that most of all, it shows the value of taking the time to question conventional wisdom.

“I had no idea I was going to work on bird pee,” Crouch said, “but I find myself with so many new questions about the avian microbiome, which shows how our research can take us in unexpected and exciting directions.”

Contacts and sources:
Anton Caputo, Jackson School of Geosciences
University of Texas - Austin

Citation: A re-evaluation of the chemical composition of avian urinary excreta. Nicholas M. A. Crouch, Vincent M. Lynch, Julia A. Clarke. Journal of Ornithology, 2019; DOI: 10.1007/s10336-019-01692-5

Machu Picchu: Ancient Incan Sanctuary Intentionally Built on Faults

The ancient Incan sanctuary of Machu Picchu is considered one of humanity’s greatest architectural achievements. Built in a remote Andean setting atop a narrow ridge high above a precipitous river canyon, the site is renowned for its perfect integration with the spectacular landscape. But the sanctuary’s location has long puzzled scientists: Why did the Incas build their masterpiece in such an inaccessible place? Research suggests the answer may be related to the geological faults that lie beneath the site.

On Monday, 23 September 2019, at the GSA Annual meeting in Phoenix, Rualdo Menegat, a geologist at Brazil’s Federal University of Rio Grande do Sul,  presented the results of a detailed geoarchaeological analysis that suggests the Incas intentionally built Machu Picchu—as well as some of their cities—in locations where tectonic faults meet. “Machu Pichu’s location is not a coincidence,” says Menegat. “It would be impossible to build such a site in the high mountains if the substrate was not fractured.”

Machu Pichu. Detailed mapping indicates the World Heritage Site’s location and layout were dictated by the underlying geological faults. Photo taken 5 Nov. 2010
Machu Pichu
Credit: Rualdo Menegat

Using a combination of satellite imagery and field measurements, Menegat mapped a dense web of intersecting fractures and faults beneath the UNESCO World Heritage Site. His analysis indicates these features vary widely in scale, from tiny fractures visible in individual stones to major, 175-kilometer-long lineaments that control the orientation of some of the region’s river valleys.

Menegat found that these faults and fractures occur in several sets, some of which correspond to the major fault zones responsible for uplifting the Central Andes Mountains during the past eight million years. Because some of these faults are oriented northeast-southwest and others trend northwest-southeast, they collectively create an “X” shape where they intersect beneath Machu Picchu.

Ollantaytambo, Peru: The Incas took advantage of pre-existing fractures in local stones to reduce the amount of energy needed to create their master stonework. Photo taken 21 July 2016,
Incan Stonework
Credit: Terri Cook and Lon Abbott.

Menegat’s mapping suggests that the sanctuary’s urban sectors and the surrounding agricultural fields, as well as individual buildings and stairs, are all oriented along the trends of these major faults. “The layout clearly reflects the fracture matrix underlying the site,” says Menegat. Other ancient Incan cities, including Ollantaytambo, Pisac, and Cusco, are also located at the intersection of faults, says Menegat. “Each is precisely the expression of the main directions of the site’s geological faults.”

Menegat’s results indicate the underlying fault-and-fracture network is as integral to Machu Picchu’s construction as its legendary stonework. This mortar-free masonry features stones so perfectly fitted together that it’s impossible to slide a credit card between them. As master stoneworkers, the Incas took advantage of the abundant building materials in the fault zone, says Menegat. “The intense fracturing there predisposed the rocks to breaking along these same planes of weakness, which greatly reduced the energy needed to carve them.”

Natural block in Machu Picchu Mountain. The local network of faults and fractures is visible in the blocks of rock integrated into Machu Picchu’s structures. Photo taken 6 Nov 2010 
block fractured
Credit: Rualdo Menegat.

In addition to helping shape individual stones, the fault network at Machu Picchu likely offered the Incas other advantages, according to Menegat. Chief among these was a ready source of water. “The area’s tectonic faults channeled meltwater and rainwater straight to the site,” he says. Construction of the sanctuary in such a high perch also had the benefit of isolating the site from avalanches and landslides, all-too-common hazards in this alpine environment, Menegat explains.

The faults and fractures underlying Machu Picchu also helped drain the site during the intense rainstorms prevalent in the region. “About two-thirds of the effort to build the sanctuary involved constructing subsurface drainages,” says Menegat. “The preexisting fractures aided this process and help account for its remarkable preservation,” he says. “Machu Picchu clearly shows us that the Incan civilization was an empire of fractured rocks.”

Contacts and sources:
Christa Stratton, Geological Society of America
Rualdo Menegat, Federal University of Rio Grande do Sul, Brazil

Session No. 148 – T126. Geoarchaeological Insights into Paleoenvironmental Reconstruction and Cultural Dynamics
Monday, 23 Sept.: 1:30 to 5:30 p.m.
Presentation time: 3:50 to 4:05 p.m.
Room 125AB, North Building (Phoenix Convention Center)
Session Link:
Paper 148-9: How Incas Used Geological Faults to Build Their Settlements
Abstract Link:

Tuesday, September 24, 2019

Is Theory on Earth’s Climate in the Last 15 Million Years Wrong?

A Rutgers-led study casts doubt on Himalayan rock weathering hypothesis.

A key theory that attributes the climate evolution of the Earth to the breakdown of Himalayan rocks may not explain the cooling over the past 15 million years, according to a Rutgers-led study.

The study in the journal Nature Geoscience could shed more light on the causes of long-term climate change. It centers on the long-term cooling that occurred before the recent global warming tied to greenhouse gas emissions from humanity.

Left: Large coccoliths – disks made of calcium carbonate that armor single-celled algae called coccolithophores – from the Middle Miocene about 16 million to 11.6 million years ago. Right: Small coccoliths from the Pleistocene about 2.6 million to 11,700 years ago.
Left: Large coccoliths – disks made of calcium carbonate that armor single-celled algae called coccolithophores – from the Middle Miocene about 16 million to 11.6 million years ago. Right: Small coccoliths from the Pleistocene about 2.6 million to 11,700 years ago.
Credit: Weimin Si

“The findings of our study, if substantiated, raise more questions than they answered,” said senior author Yair Rosenthal, a distinguished professor in the Department of Marine and Coastal Sciences in the School of Environmental and Biological Sciences at Rutgers University–New Brunswick. “If the cooling is not due to enhanced Himalayan rock weathering, then what processes have been overlooked?”

For decades, the leading hypothesis has been that the collision of the Indian and Asian continents and uplifting of the Himalayas brought fresh rocks to the Earth’s surface, making them more vulnerable to weathering that captured and stored carbon dioxide – a key greenhouse gas. But that hypothesis remains unconfirmed.

Lead author Weimin Si, a former Rutgers doctoral student now at Brown University, and Rosenthal challenge the hypothesis and examined deep-sea sediments rich with calcium carbonate.

Over millions of years, the weathering of rocks captured carbon dioxide and rivers carried it to the ocean as dissolved inorganic carbon, which is used by algae to build their calcium carbonate shells. When algae die, their skeletons fall on the seafloor and get buried, locking carbon from the atmosphere in deep-sea sediments.

If weathering increases, the accumulation of calcium carbonate in the deep sea should increase. But after studying dozens of deep-sea sediment cores through an international ocean drilling program, Si found that calcium carbonate in shells decreased significantly over 15 million years, which suggests that rock weathering may not be responsible for the long-term cooling.

Meanwhile, the scientists – surprisingly – also found that algae called coccolithophores adapted to the carbon dioxide decline over 15 million years by reducing their production of calcium carbonate. This reduction apparently was not taken into account in previous studies.

Many scientists believe that ocean acidification from high carbon dioxide levels will reduce the calcium carbonate in algae, especially in the near future. The data, however, suggest the opposite occurred over the 15 million years before the current global warming spell.

Rosenthal’s lab is now trying to answer these questions by studying the evolution of calcium and other elements in the ocean.

Contacts and sources:
Rutgers University-New Brunswick

Citation: Reduced continental weathering and marine calcification linked to late Neogene decline in atmospheric CO2 Weimin Si & Yair Rosenthal Nature Geoscience (2019)

Hormone Potentially Linked to Hypersexual Disorder Identified

The Mayo Clinic states "compulsive sexual behavior is sometimes called hypersexuality, hypersexuality disorder or sexual addiction. It's an excessive preoccupation with sexual fantasies, urges or behaviors that is difficult to control, causes you distress, or negatively affects your health, job, relationships or other parts of your life."

A new study of men and women with hypersexual disorder has revealed a possible role of the hormone oxytocin, according to results published in the journal Epigenetics. The finding could potentially open the door to treating the disorder by engineering a way to suppress its activity.

Oxytocin molecue representation
Credit: Fvasconcellos / Wikimedia Commmons

Hypersexual disorder, or an overactive sex drive, is recognized as a compulsive sexual behaviour disorder, listed as an impulse-control disorder by the World Health Organisation. It can be characterised by obsessive thoughts of sex, a compulsion to perform sexual acts, a loss of control, or sexual habits that carry potential problems or risks. While prevalence estimates vary, literature indicates that hypersexual disorder affects 3-6% of population.

Controversy surrounds diagnosis because it often occurs alongside other mental health issues, suggesting it could be an extension or manifestation of an existing mental disorder. Little is known about the neurobiology behind it.

"We set out to investigate the epigenetic regulatory mechanisms behind hypersexual disorder so we could determine whether it has any hallmarks that make it distinct from other health issues," says lead author Adrian Boström from the Department of Neuroscience at Uppsala University, Sweden who conducted the study with researchers from the Andrology/Sexual Medicine Group (ANOVA) at Karolinska Institutet, Stockholm, Sweden.

"To our knowledge, our study is the first to implicate dysregulated epigenetic mechanisms of both DNA methylation and microRNA activity and the involvement of oxytocin in the brain among patients seeking treatment for hypersexuality."

The scientists measured DNA methylation patterns in the blood from 60 patients with hypersexual disorder and compared them to samples from 33 healthy volunteers.

They investigated 8,852 regions of DNA methylation associated to nearby microRNAs to identify any variations between samples. DNA methylation can affect gene expression and the function of genes, typically acting to reduce their activity. Where changes in DNA methylation were detected, the researchers investigated levels of gene expression of the associated microRNA. MicroRNAs are particularly interesting as they can pass the blood-brain-barrier and modulate or degrade the expression of up to several hundred different genes in brain and other tissues.

They also compared their findings to samples from 107 subjects, 24 of whom were alcohol-dependent, to explore an association with addictive behaviour.

Results identified two regions of DNA that were altered in hypersexual disorder patients. Normal function of DNA methylation was disrupted and an associated microRNA, involved in gene silencing, was found to be under-expressed. Analysis revealed that the microRNA identified, microRNA-4456, targets genes that are normally expressed at particularly high levels in the brain and that are involved in the regulation of the hormone oxytocin. With gene silencing reduced, oxytocin may be expected to be at elevated levels, although the current study does not confirm this.

It has been seen in specific vole and primate species the neuropeptide oxytocin plays a central role in the regulation of pair-bonding behaviour. Previous studies have demonstrated that oxytocin is associated with the regulation of social and pair-bonding, sexual reproduction and aggressive behaviour in both men and women. The comparison with alcohol-dependent subjects revealed the same DNA region to be significantly under-methylated, suggesting that it may be primarily associated with the addictive components of hypersexual disorder, such as sex addiction, dysregulated sexual desire, compulsivity and impulsivity.

"Further research will be needed to investigate the role of microRNA-4456 and oxytocin in hypersexual disorder, but our results suggest it could be worthwhile to examine the benefits of drug and psychotherapy to reduce the activity of oxytocin," says Professor Jussi Jokinen from Umeå University, Sweden.

The authors note that a limitation of the study is that the mean difference in DNA methylation between hypersexual disorder patients and healthy volunteers was only around 2.6%, so the impact on physiological changes might be called into question. However, a growing body of evidence suggestions that just subtle methylation changes can have wide-ranging consequences for complex conditions such as depression or schizophrenia.

The study was funded through a regional agreement between Umeå University and Västerbotten County Council (ALF) and by grants provided by the Stockholm County Council as well as by the Swedish Research Foundation, the Åhlens Foundation, the Novo Nordisk Foundation, and the Swedish Brain Research Foundation.

The labels have been added to top of this press release as part of a project run by the Academy of Medical Sciences seeking to improve the communication of evidence. For more information, please see:

Contacts and sources:
Krystina Sihdu , Taylor & Francis
Adrian Boström, Uppsala University, Sweden
Professor Jussi Jokinen, Umeå University, Sweden

Citation: Hypermethylation-associated downregulation of microRNA-4456 in hypersexual disorder with putative influence on oxytocin signalling: A DNA methylation analysis of miRNA genes Adrian E. Boström ,Andreas Chatzittofis ,Diana-Maria Ciuculete, John N. Flanagan, Regina Krattinger,Marcus BandsteinORCID Icon,Jessica Mwinyi, Gerd A. Kullak-Ublick,Katarina Görts Öberg,Stefan A rver,Helgi B. Schiöth &Jussi Jokinen

Monday, September 23, 2019

Artificial Intelligence Probes Dark Matter in the Universe

Understanding the how our universe came to be what it is today and what will be its final destiny is one of the biggest challenges in science. The awe-inspiring display of countless stars on a clear night gives us some idea of the magnitude of the problem, and yet that is only part of the story. The deeper riddle lies in what we cannot see, at least not directly: dark matter and dark energy. With dark matter pulling the universe together and dark energy causing it to expand faster, cosmologists need to know exactly how much of those two is out there in order to refine their models.

At ETH Zurich, scientists from the Department of Physics and the Department of Computer Science have now joined forces to improve on standard methods for estimating the dark matter content of the universe through artificial intelligence. They used cutting-edge machine learning algorithms for cosmological data analysis that have a lot in common with those used for facial recognition by Facebook and other social media. Their results have recently been published in the scientific journal Physical Review D.

This is a typical computer-generated dark matter map used by the researchers to train the neural network
dark matter map
Credit:  ETH Zurich

Facial recognition for cosmology

While there are no faces to be recognized in pictures taken of the night sky, cosmologists still look for something rather similar, as Tomasz Kacprzak, a researcher in the group of Alexandre Refregier at the Institute of Particle Physics and Astrophysics, explains: "Facebook uses its algorithms to find eyes, mouths or ears in images; we use ours to look for the tell-tale signs of dark matter and dark energy." As dark matter cannot be seen directly in telescope images, physicists rely on the fact that all matter - including the dark variety - slightly bends the path of light rays arriving at the Earth from distant galaxies. This effect, known as "weak gravitational lensing", distorts the images of those galaxies very subtly, much like far-away objects appear blurred on a hot day as light passes through layers of air at different temperatures.

Cosmologists can use that distortion to work backwards and create mass maps of the sky showing where dark matter is located. Next, they compare those dark matter maps to theoretical predictions in order to find which cosmological model most closely matches the data. Traditionally, this is done using human-designed statistics such as so-called correlation functions that describe how different parts of the maps are related to each other. Such statistics, however, are limited as to how well they can find complex patterns in the matter maps.

Neural networks teach themselves

"In our recent work, we have used a completely new methodology", says Alexandre Refregier. "Instead of inventing the appropriate statistical analysis ourselves, we let computers do the job." This is where Aurelien Lucchi and his colleagues from the Data Analytics Lab at the Department of Computer Science come in. Together with Janis Fluri, a PhD student in Refregier's group and lead author of the study, they used machine learning algorithms called deep artificial neural networks and taught them to extract the largest possible amount of information from the dark matter maps.

In a first step, the scientists trained the neural networks by feeding them computer-generated data that simulates the universe. That way, they knew what the correct answer for a given cosmological parameter - for instance, the ratio between the total amount of dark matter and dark energy - should be for each simulated dark matter map. By repeatedly analysing the dark matter maps, the neural network taught itself to look for the right kind of features in them and to extract more and more of the desired information. In the Facebook analogy, it got better at distinguishing random oval shapes from eyes or mouths.

Once the neural net­work has been trained, it can be used to ex­tract cos­mo­log­i­cal pa­ra­me­ters from 
ac­tual im­ages of the night sky. 
Neural network
Credit:  ETH Zurich

More accurate than human-made analysis

The results of that training were encouraging: the neural networks came up with values that were 30% more accurate than those obtained by traditional methods based on human-made statistical analysis. For cosmologists, that is a huge improvement as reaching the same accuracy by increasing the number of telescope images would require twice as much observation time - which is expensive.

Finally, the scientists used their fully trained neural network to analyse actual dark matter maps from the KiDS-450 dataset. "This is the first time such machine learning tools have been used in this context," says Fluri, "and we found that the deep artificial neural network enables us to extract more information from the data than previous approaches. We believe that this usage of machine learning in cosmology will have many future applications."

As a next step, he and his colleagues are planning to apply their method to bigger image sets such as the Dark Energy Survey. Also, more cosmological parameters and refinements such as details about the nature of dark energy will be fed to the neural networks.

Contacts and sources:
Janis Fluri
ETH Zurich

Citation: Cosmological constraints with deep learning from KiDS-450 weak lensing maps   Fluri J, Kacprzak T, Lucchi A, Refregier A, Amara A, Hofmann T, Schneider A: . Physical Review D. 100: 063514, doi: 10.1103/PhysRevD.100.063514

Common Childhood Illness Took Down the Neanderthals?

A 21st century nuisance for parents may have proved deadly to early man.

It is one of the great unsolved mysteries of anthropology. What killed off the Neanderthals, and why did Homo sapiens thrive even as Neanderthals withered to extinction? Was it some sort of plague specific only to Neanderthals? Was there some sort of cataclysmic event in their homelands of Eurasia that lead to their disappearance?

A new study from a team of physical anthropologists and head & neck anatomists suggests a less dramatic but equally deadly cause.

Published online by the journal, The Anatomical Record, the study, "Reconstructing the Neanderthal Eustachian Tube: New Insights on Disease Susceptibility, Fitness Cost, and Extinction"1 suggests that the real culprit in the demise of the Neanderthals was not some exotic pathogen.

This illustration shows the structure of the Eustachian Tube in Neanderthal Man and it's similarity to the human infant.
Credit: SUNY Downstate Health Sciences University

Instead, the authors believe the path to extinction may well have been the most common and innocuous of childhood illnesses - and the bane of every parent of young children - chronic ear infections.

"It may sound far-fetched, but when we, for the first time, reconstructed the Eustachian tubes of Neanderthals, we discovered that they are remarkably similar to those of human infants," said coinvestigator and Downstate Health Sciences University Associate Professor Samuel Márquez, PhD, "Middle ear infections are nearly ubiquitous among infants because the flat angle of an infant's Eustachian tubes is prone to retain the otitis media bacteria that cause these infections - the same flat angle we found in Neanderthals."

In this age of antibiotics, these infections are easy to treat and relatively benign for human babies. Additionally, around age 5, the Eustachian tubes in human children lengthen and the angle becomes more acute, allowing the ear to drain, all but eliminating these recurring infections beyond early childhood.

But unlike modern humans, the structure of the Eustachian tubes in Neanderthals do not change with age - which means these ear infections and their complications, including respiratory infections, hearing loss, pneumonia, and worse, would not only become chronic, but a lifelong threat to overall health and survival.

"It's not just the threat of dying of an infection," said Dr. Márquez. "If you are constantly ill, you would not be as fit and effective in competing with your Homo sapien cousins for food and other resources. "In a world of survival of the fittest, it is no wonder that modern man, not Neanderthal, prevailed."

"The strength of the study lies in reconstructing the cartilaginous Eustachian tube," said Richard Rosenfeld, MD, MPH, MBA, Distinguished Professor and Chairman of Otolaryngology at SUNY Downstate and a world-renowned authority on children's health. "This new and previously unknown understanding of middle ear function in Neanderthal is what allows us to make new inferences regarding the impact on their health and fitness."

"Here is yet another intriguing twist on the ever-evolving Neanderthal story, this time involving a part of the body that researchers had almost entirely neglected," said Ian Tattersall, Ph.D., paleoanthropologist and Curator Emeritus of the American Museum of National History. "It adds to our gradually emerging picture of the Neanderthals as very close relatives who nonetheless differed in crucial respects from modern man."


Contacts and sources:
John Gillespie
SUNY Downstate Health Sciences University

Citation:  Reconstructing the Neanderthal Eustachian Tube: New Insights on Disease Susceptibility, Fitness Cost, and Extinction
The Anatomical Record
Anthony Santino Pagano, PhD, Samuel Márquez, PhD, Jeffrey T. Laitman, PhD
Published online August 31, 2019

Croc-like Creature Terrorized Triassic Dinosaurs 210 Million Years Ago

Rauisuchians fed on vegetarian dinosaurs according to Wits student Rick Tolchard.

Giant, predatory croc-like animals that lived during the Triassic period in southern Africa preyed on early dinosaurs and mammal relatives 210 million years ago. These predators, known as “rauisuchians” preyed on early herbivore dinosaurs and their mammal relatives living at the time, according to Wits Masters student Rick Tolchard.

“These ancient fossils provide us with evidence of how at least two predator species hunted these vegetarian dinosaurs 210 million-years-ago. It is amazing to follow the clues left behind in fossilised teeth, jaws, limbs and other fossils to help us tell the ancient story of life in southern Africa,” says Tolchard.

Artist's reconstruction of two rauisuchians fighting over a desiccated corpse of a mammal-relative in the Triassic of southern Africa. In the background, dinosaurs and mammal-like reptiles form other parts of the ecosystem.

Credit: Viktor Radermacher, owns copyright

The fossils studied by Tolchard include teeth, pieces of jaws, hind limbs and body armour, all of which are can be described as parts of rauisuchians.

Rauisuchians are closely related to crocodiles as we know them today. They had a diversity of body shapes and sizes during the Triassic period. The specimens described in this research include some of the largest carnivorous members of this group, that were possibly up to 10 metres long, with huge skulls full of serrated, curved teeth.

Example of rauisuchian teeth in the Wits collections

Credit: Wits University

The study, published online in the Journal of African Earth Sciences last week, shows that the rauisuchians were some of the latest-surviving members of their group, and that when they were alive, they were thriving close to the Antarctic Circle – the theoretical limit for their physiology.

“In the Triassic period, rauisuchians were widespread and their fossils are known from all continents except Antarctica,” adds Tolchard. “They went extinct about 200 million years ago, paving the way for dinosaurs to become the dominant large land animals.”

“Rick’s study demonstrates the value of re-examining old specimens, and now we finally know what was preying on all those herbivorous dinosaurs!” says Professor Jonah Choiniere, Rick’s advisor and Professor of Comparative Palaeobiology at the Wits Evolutionary Studies Institute.

Rick Tolchard studying rauisuchians in the Geological Survey in Namibia.

Credit: Helke Mocke

Tolchard studied fossils from collections based at the the University of the Witwatersrand, the Iziko South African Museum and the National Museum in Bloemfontein. He was joined in the research by an international team, including researchers from the USA, Argentina and the UK.

Contacts and sources:
Rick Tolchard
University of Witwatersrand

Citation: ‘Rauisuchian’ material from the lower Elliot Formation of South Africa and Lesotho: Implications for Late Triassic biogeography and biostratigraphy
Journal of African Earth Sciences
Volume 160, December 2019, 103610

DNA Held Together by Hydrophobic Forces

Researchers at Chalmers University of Technology, Sweden, disprove the prevailing theory of how DNA binds itself. It is not, as is generally believed, hydrogen bonds which bind together the two sides of the DNA structure. Instead, water is the key. The discovery opens doors for new understanding in research in medicine and life sciences. The researchers' findings are presented in the journal PNAS.

DNA is constructed of two strands, consisting of sugar molecules and phosphate groups. Between these two strands are nitrogen bases, the compounds which make up organisms' genes, with hydrogen bonds between them. Until now, it was commonly thought that those hydrogen bonds were what held the two strands together.

For DNA to be read, replicated or repaired, DNA molecules must open themselves. This happens when the cells use a catalytic protein to create a hydrophobic environment around the molecule.

Credit: Illustration: Yen Strandqvist/Chalmers University of Technology

But now, researchers from Chalmers University of Technology show that the secret to DNA's helical structure may be that the molecules have a hydrophobic interior, in an environment consisting mainly of water. The environment is therefore hydrophilic, while the DNA molecules' nitrogen bases are hydrophobic, pushing away the surrounding water. When hydrophobic units are in a hydrophilic environment, they group together, to minimise their exposure to the water.

The role of the hydrogen bonds, which were previously seen as crucial to holding DNA helixes together, appear to be more to do with sorting the base pairs, so that they link together in the correct sequence.

The discovery is crucial for understanding DNA's relationship with its environment.

"Cells want to protect their DNA, and not expose it to hydrophobic environments, which can sometimes contain harmful molecules," says Bobo Feng, one of the researchers behind the study. "But at the same time, the cells' DNA needs to open up in order to be used."

"We believe that the cell keeps its DNA in a water solution most of the time, but as soon as a cell wants to do something with its DNA, like read, copy or repair it, it exposes the DNA to a hydrophobic environment."

Reproduction, for example, involves the base pairs dissolving from one another and opening up. Enzymes then copy both sides of the helix to create new DNA. When it comes to repairing damaged DNA, the damaged areas are subjected to a hydrophobic environment, to be replaced. A catalytic protein creates the hydrophobic environment. This type of protein is central to all DNA repairs, meaning it could be the key to fighting many serious sicknesses.

Understanding these proteins could yield many new insights into how we could, for example, fight resistant bacteria, or potentially even cure cancer. Bacteria use a protein called RecA to repair their DNA, and the researchers believe their results could provide new insight into how this process works - potentially offering methods for stopping it and thereby killing the bacteria.

In human cells, the protein Rad51 repairs DNA and fixes mutated DNA sequences, which otherwise could lead to cancer.

"To understand cancer, we need to understand how DNA repairs. To understand that, we first need to understand DNA itself," says Bobo Feng. "So far, we have not, because we believed that hydrogen bonds were what held it together. Now, we have shown that instead it is the hydrophobic forces which lie behind it. We have also shown that DNA behaves totally differently in a hydrophobic environment. This could help us to understand DNA, and how it repairs. Nobody has previously placed DNA in a hydrophobic environment like this and studied how it behaves, so it's not surprising that nobody has discovered this until now."

Bobo Feng, Postdoc, Chemistry and Chemical Engineering, Chalmers University of Technology.
Credit: Johan Bodell/Chalmers University of Technology

More information on the methods the researchers used to show how DNA binds together:

The researchers studied how DNA behaves in an environment which is more hydrophobic than normal, a method they were the first to experiment with.

They used the hydrophobic solution polyethylene glycol, and step-by-step changed the DNA's surroundings from the naturally hydrophilic environment to a hydrophobic one. They aimed to discover if there is a limit where DNA starts to lose its structure, when the DNA does not have a reason to bind, because the environment is no longer hydrophilic. The researchers observed that when the solution reached the borderline between hydrophilic and hydrophobic, the DNA molecules' characteristic spiral form started to unravel.

Upon closer inspection, they observed that when the base pairs split from one another (due to external influence, or simply from random movements), holes are formed in the structure, allowing water to leak in. Because DNA wants to keep its interior dry, it presses together, with the base pairs coming together again to squeeze out the water. In a hydrophobic environment, this water is missing, so the holes stay in place.

Contacts and sources:
Johanna WildeChalmers University of Technology

Citation: "Hydrophobic catalysis and a potential biological role of DNA unstacking induced by environment effects" in the journal Proceedings of the National Academy of Sciences of the United States of America (PNAS):

Modern Humans, One Species, Many Origins

Modern humans evolved in Africa, and we now know that human groups from all over the continent contributed to that process. A group of scientists says that means it is time to stop arguing about where in Africa humans 'really' came from

In a paper published in Nature Ecology and Evolution, a group of researchers argue that our evolutionary past must be understood as the outcome of dynamic changes in connectivity, or gene flow, between early humans scattered across Africa. Viewing past human populations as a succession of discrete branches on an evolutionary tree may be misleading, they said, because it reduces the human story to a series of “splitting times” which may be illusory.

World map with land area resized to represent modern human genetic diversity and colour representing Neanderthal plus Denisovan ancestry. As can be seen, contributions from other populations to the Homo sapiens gene pool are small and unevenly distributed. Africa is disproportionately large because the great human genetic diversity – and hence the roots of humanity – are found here. 

© James Cheshire/Mark G. Thomas

According to archaeologist Dr. Eleanor Scerri and geneticists Dr. Lounès Chikhi and Professor Mark Thomas, the quest for a single original location for modern humans is a wild goose chase. “People like us began to appear sometime between 500,000 and 300,000 years ago,” says Dr. Scerri, group leader of the Pan-African Evolution Research Group at the Max Planck Institute for the Science of Human History and lead author of the study. “That is something in the order of 8000 generations, a long time for early people to move around and explore a big space. Their movements, patterns of mixing and genetic exchanges are what gave rise to us.”

Making sense of a scattered record

“The genetics of contemporary humans are very clear. The greatest genetic diversity is found in Africans,” explains Prof. Thomas of University College London. “The old theory that we descend from regional populations spread across the Old World over the last million years or so is not supported by genetics data. Sure, non-Africans today have some ancestry from Neanderthals, and some have appreciable ancestry from the recently discovered Denisovans. And maybe other, as yet undiscovered ancient hominin groups also interbred with us, Homo sapiens. But none of this changes the fact that more than 90% of the ancestry of everybody in the world lies in Africa over the last 100,000 years.”

“The problem is that knowing that we are an African species has led many to ask the question ‘where in Africa’,” he adds. “Superficially this is a reasonable question. But when we consider the genetic patterns alongside what we know of fossils, ancient tools, and ancient climates, the ‘single region of origin’ view just doesn’t cut it, and we have to start thinking differently. This means different models, and we argue in the current paper that structured population models are the way forward.”

"Viewed through the lens of dynamic changes in connectivity – or metapopulations, to be technical – the interpretation of the available data changes," states Dr. Chikhi of the CNRS Evolution et Diversité Biologique lab at the University of Toulouse and Principal Investigator at the Gulbenkian Institute of Science in Lisbon. "Instead of a series of population splits branching off an ancestral tree, changes in connectivity between different populations over time seem a more reasonable assumption, and appear to explain several patterns of genomic diversity not explained by current alternative models. Metapopulations are the kind of model you'd expect if people were moving around and mixing over long periods and wide geographic areas. We cannot objectively identify this geographic area today from genetic data alone, but data from other disciplines suggest that the African continent represents the most likely geographical scale."

“A dynamic interconnected patchwork of populations”

Different models of population history. T0 and T1 represent time slices in the present and past, respectively. a) A metapopulation, which includes population fission, fusion, gene flow and local extinction. b) A tree model, which includes population fission and extinction only. 
© Claudiu Pantiru/Max Planck Institute for the Science of Human History

The scientists argue that this view is not only better supported by the fossil, genetic and archaeological evidence, it also better explains the palaeoanthropological record beyond Africa.

"We see physically diverse early human fossils from across Africa, some very old genetic lineages and a pan-African shift in technology and material culture that reflects advanced cognition, including new technical and social innovations, across the continent. In other words, what you'd expect from a dynamic interconnected patchwork of populations that were at times more or less isolated from each other," says Dr. Scerri. “This would also help to explain the increasing evidence for unexpected populations, including in areas outside Africa such as the Hobbits on Flores,” she adds.

The authors stress that all this means that the scientific community may finally have the means to address complex questions in human evolutionary studies that could not be addressed previously. Dr. Chikhi notes, “We have so much new data now from genetics, archaeology and fossils, and a better understanding of how past climates and environments affected early people. We have come to a point where the old models are constraining progress in our understanding of the past.”

"A metapopulation model helps us to find a way to acknowledge the paleontological, archaeological and genetic evidence for a recent African origin with limited gene flow from non-African metapopulations, such as Neanderthals, without falling into overly polemic and restrictive debates,” adds Dr. Scerri.

The authors state that any model that would claim to represent human evolution would have to satisfactorily explain patterns of variation in genetic, morphological and cultural data components, and be consistent with the climatic changes that have shaped our ecologies during most of the last one million years.

“A structured metapopulation model does this without denying any of the latest evidence. It doesn’t require us to find a mythical region of origin, or to date clean splitting events whose meaning is far from clear. Population tree models force us to think in such terms, and this can be very misleading,” says Dr. Chikhi.

How to understand our origins

The researchers acknowledge that the past was a confusing place and that old models, while largely discredited now, have been helpful for making sense of a record with many gaps in it. Models can be very useful even when they are wrong, but when they are prioritized over the data they can constrain progress.

“Convergent evidence from different fields stress the importance of considering a metapopulation structure in our models of human evolution,” says Prof. Thomas. Dr. Chikhi adds, “This complex history of population subdivision should thus lead us to question current models of ancient population size changes, and perhaps re-interpret some of the old bottlenecks as changes in connectivity.”

“If we look at the available data through the lens of changes in connectivity, the record starts to make a lot more sense. We need such flexibility to be able to make sense of the past, or we get lost in a malaise of ever-increasing named species, failed trajectories and population trees that never existed,” says Prof. Thomas. “Science always favours the simpler explanation and it is becoming increasingly difficult to stick to old narratives when they have to become over-complicated in order to stay relevant,” he adds.

“Our African origins cannot be denied, but we definitely don’t yet have the resolution to include or exclude different bits of evidence simply because they don’t fit with a particular view. We need better reasons than that,” says Dr. Scerri.

Contacts and sources:
Petra Mader
The Max Planck Institute for the Science of Human History (MPI-SHH)

Citation: Beyond Multiregional and Simple Out of Africa Models of Human Evolution Eleanor M.L. Scerri, Lounès Chikhi, Mark G. Thomas
Nature Ecology and Evolution, DOi: 10.1038/s41559-019-0992-1

Microplastics in the Great Lakes: Becoming Benthic

From the Great Pacific garbage patch to inland rivers, plastics are among the most widespread contaminants on Earth. Microplastics—particles of plastic smaller than five millimeters—are especially pervasive. As they build up in Earth’s waters, microplastics are also becoming a permanent part of the planet’s sedimentary layers.

Now, using the Great Lakes as a laboratory, sedimentary petrologist Patricia Corcoran and her students at the University of Western Ontario are studying the behavior of microplastics as a geologic phenomenon.

Microplastic pellets from the Great Lakes study. The pellet study involved sampling of 66 beaches on each Great Lake over a two-week period in October 2018, with a total of 12,974 pellets on 660 square meters of beach. 
Credit: Patricia Corcoran.

What are the main sources of microplastics to Great Lakes sediment? What factors influence their distribution, and where do they concentrate? To explore these questions, and shed light on implications such as which animals may be at risk from microplastics, Corcoran’s team has analyzed offshore and nearshore sediment samples from Lakes Huron, Ontario, Erie, and St. Clair, and their tributaries. Abundances were as high as 4270 microplastics particles per kilogram of dry weight sediment in lake sediment, and up to 2444 microplastic particles per kilogram in river sediment.

The team found that the more organic debris in the sample, the more microplastics. Benthic microplastics—those incorporated into lake bottom sediments—were also more abundant near high population areas, which are also associated with plastics industry locations.

Surprisingly, not all plastic fibers found in benthic samples were plastic after all. “When we chemically analyzed fibers only 33% were plastic. The others materials like dyed cotton or cellulose,” Corcoran says. “So we can’t assume that every fiber we see under the microscope is plastic.”\

Corcoran’s team also sampled pellets (microplastics about the size of a lentil) from 66 beaches across all five Great Lakes. They found a total of 12, 974 pellets over 660 square meters of beach, about equivalent to an eighth the area of an American football field. 

Microplastics analyzed from nearshore and offshore benthic sediment samples in lakes, benthic sediment samples in rivers, and water samples in lakes and rivers. 
Image courtesy Patricia Corcoran.

Except for the two beaches containing the most pellets, they found little relationship between population density or industry and number of pellets, says Corcoran. Instead, pellets were most concentrated near tributaries. “In other words,” she says, “rivers and creeks are the main pathways used by pellets to reach the lakes.”

Burial of microplastics in lake and river sediment is just one way Corcoran has explored how plastics are becoming part of Earth’s future rock record. She’s also investigated anthropogenic stones on a Hawaiian beach, which she and colleagues called “plastiglomerate.”

The Great Lakes study will be presented by Sara Belontz of the University of Western Ontario, on Tuesday, 24 Sept., at 2:30 p.m., in Room 224A, North Building of the Phoenix Convention Center.

Contacts and sources:
Christa Stratton
The Geological Society of America

Dr. Patricia Corcoran
Associate Professor and Department Chair
Department of Earth Sciences
University of Western Ontario

Citation: Paper 227-5: Anthropogenic Grains: Microplastics in Benthic Compartments of the Great Lakes Watershed

New Evidence of the Sahara’s Age

The Sahara Desert is vast, generously dusty, and surprisingly shy about its age. New research looking into what appears to be dust that the Sahara blew over to the Canary Islands is providing the first direct evidence from dry land that the age of the Sahara matches that found in deep-sea sediments: at least 4.6 million years old.

“People have been trying to figure it out for several decades,” said Daniel Muhs, a geologist with the U.S. Geological Survey in Denver, Colorado. “More recent studies said it was the beginning of the Pleistocene (about 2.6 million years ago). Then others say a few thousand years ago.” Added to this is a model suggesting the Sahara Desert first appeared as far back as seven million years ago.

Desert dust from Africa is transported west to the Canary Islands and the CapeVerde Islands every year. Moderate Resolution Imaging Spectroradiometer (MODIS) image of “Calima” (dust storm) event on 8 March 2006, taken from the Terra satellite. 
Image courtesy of Jeff Schmaltz, MODIS Land Rapid Response Team at NASA/GSFC.

There is also other evidence that the desert has taken breaks and had wetter, greener periods interspersed with arid times. It’s this sensitivity to climate—and the Sahara’s role in global climate—that makes the region so interesting to researchers.

The new work by Muhs and his colleagues in the Canary Islands focused on thick layers of fine reddish-brown soil found among layers of volcanic rocks and dune sands on Fuerteventura and Gran Canaria islands. The islands are off the west coast of North Africa, at the mouth of a spigot that seasonally pours windblown dust off of the Sahara and across the Atlantic Ocean. Muhs is presenting the results tomorrow at the annual meeting of the Geological Society of America in Phoenix, Arizona.

View from the ground on the Canary Islands on 8 March 2006, when the Calima arrived. 
Credit: Daniel Muhs.

Muhs’s and his colleagues’ mission was to find, identify, and date any layers of ancient African dust in what are called paleosols, or buried, ancient soils. In one coastal location studied, they found layers of dunes made from local shells of sea animals; in another, there were layers of lava from the volcanoes that built the islands. Both of these geologic archives contained paleosols made of very fine-grained minerals rich in quartz and mica—minerals that do not reflect the local geology of the islands. They do, however, reflect the minerals found on the nearby African mainland.

Luckily for the geologists, the lava flows that sandwich the windblown fine-grained quartz and mica layers made it possible to nail down approximate ages of the Saharan dust. This is because volcanic rocks contain minerals with what are essentially isotopic clocks that start ticking when the minerals in the lava cool and solidify. And since the layers of lava, paleosols, and other local soils are stacked chronologically with the youngest on top, the lava flows provide some boundaries of when the Sahara was dry enough to launch massive dusty storms out over the Atlantic.

A paleosol on the island of Gran Canaria, sandwiched between basalt flows dated to 3.0–2.9 million years ago—to the Pliocene. 
Credit: Daniel Muhs.

In all, the researchers report eight paleosols that record African dust piling up in the Canaries between about 4.8 and 2.8 million years ago, 3.0 to 2.9 million years ago, and at about 400,000 years ago. The oldest paleosols agree with the deep-sea cores, which put the earliest Sahara dust to the Atlantic at about 4.6 million years ago.

That’s not to say the Sahara is 4.6-million-years-old. That’s only as old as Muhs and his colleagues could determine based on the paleosols and lavas they found.

“We could take it further back in time if we can find the paleosols,” Muhs said.

Muhs’s presentation is entitled The Antiquity of the Sahara Desert: New Evidence From the Mineralogy and Geochemistry of Pliocene Paleosols on the Canary Islands, Spain (Paper No. 76-1; It is scheduled for Monday, 23 Sept., at 8:05 am in Room 221AB, North Building of the Phoenix Convention Center. It is part of a session titled T2. Geomorphology and Climate Change in Hot Deserts.

Field work in this study for Muhs was supported by the Farouk El-Baz Award of the Geological Society of America

Contacts and sources:
Daniel Muhs, USGS
Christa Stratton, Geological Society of America (GSA)


New Way To Capture Heat and Turn It into Electricity

An international team of scientists discovered a new way to capture heat and turn it into electricity.

The discovery, published last week in the journal Science Advances, could create more efficient energy generation from heat in things like car exhaust, interplanetary space probes and industrial processes.
Researchers have made an important discovery that could make it easier to collect energy from heat.
Credit: OSU

“Because of this discovery, we should be able to make more electrical energy out of heat than we do today,” said study co-author Joseph Heremans, professor of mechanical and aerospace engineering and Ohio Eminent Scholar in Nanotechnology at The Ohio State University. “It’s something that, until now, nobody thought was possible.”

The discovery is based on tiny particles called paramagnons—bits that are not quite magnets, but that carry some magnetic flux. This is important, because magnets, when heated, lose their magnetic force and become what is called paramagnetic. A flux of magnetism—what scientists call “spins”—creates a type of energy called magnon-drag thermoelectricity, something that, until this discovery, could not be used to collect energy at room temperature.

“The conventional wisdom was once that, if you have a paramagnet and you heat it up, nothing happens,” Heremans said. “And we found that that is not true. What we found is a new way of designing thermoelectric semiconductors—materials that convert heat to electricity. Conventional thermoelectrics that we’ve had over the last 20 years or so are too inefficient and give us too little energy, so they are not really in widespread use. This changes that understanding.”

Joseph Heremans
Credit: OSU

Magnets are a crucial part of collecting energy from heat: When one side of a magnet is heated, the other side—the cold side—gets more magnetic, producing spin, which pushes the electrons in the magnet and creates electricity.

The paradox, though, is that when magnets get heated up, they lose most of their magnetic properties, turning them into paramagnets—“almost-but-not-quite magnets,” Heremans calls them. That means that, until this discovery, nobody thought of using paramagnets to harvest heat because scientists thought paramagnets weren’t capable of collecting energy.

What the research team found, though, is that the paramagnons push the electrons only for a billionth of a millionth of a second—long enough to make paramagnets viable energy-harvesters.

The research team—an international group of scientists from Ohio State, North Carolina State University and the Chinese Academy of Sciences (all are equal authors on this journal article)—started testing paramagnons to see if they could, under the right circumstances, produce the necessary spin.

What they found, Heremans said, is that paramagnons do, in fact, produce the kind of spin that pushes electrons.

And that, he said, could make it possible to collect energy.

Ohio State graduate student Yuanhua Zheng is also an author on this work. The research was conducted in partnership with additional researchers at the U.S. Department of Energy’s Oak Ridge National Laboratory and was supported by the National Science Foundation, the Air Force Office of Scientific Research and the U.S. Department of Energy.

Contacts and sources:
Laura Arenschield
Ohio State University

Citation: Paramagnon drag in high thermoelectric figure of merit Li-doped MnTe. Y. Zheng, T. Lu, Md M. H. Polash, M. Rasoulianboroujeni, N. Liu, M. E. Manley, Y. Deng, P. J. Sun, X. L. Chen, R. P. Hermann, D. Vashaee, J. P. Heremans, H. Zhao. Science Advances, 2019; 5 (9): eaat9461 DOI: 10.1126/sciadv.aat9461