Author: Margaret Allen

Senior research writer, SMU Public Affairs

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SMU Dark Matter Day celebration culminates in a dark matter rock hunt on Halloween

“In the spirit of science being a pursuit open to all, we are excited to welcome all members of the SMU family to become dark matter hunters for a day.” — SMU physicist Jodi Cooley

This Halloween, people around the world will be celebrating the mysterious cosmic substance that permeates our universe: dark matter.

At SMU, the Department of Physics in Dedman College of Humanities and Sciences is hosting a Dark Matter Day celebration, and students, faculty, staff and DFW residents are invited to join in the educational fun with events open to the public.

To kick off the festivities, two speaking events by scientists in the field of dark matter will familiarize participants with the elusive particles that scientists refer to as dark matter. The first talk is oriented toward the general public, while the second is more technical and will appeal to people familiar with one of the STEM areas of science, technology, engineering or mathematics, particularly physics and astrophysics.

Then throughout Halloween day, everyone is invited to test their skills at finding dark matter — in this case, a series of rocks bearing educational messages related to dark matter, which the Society of Physics Students has painted and then hidden around the campus.

Anyone lucky enough to find one of the 26 rocks can present it at the Physics Department office to receive a prize, says SMU physics professor Jodi Cooley, whose research is focused on the scientific challenge of detecting dark matter.

“In the spirit of science being a pursuit open to all, we are excited to welcome all members of the SMU family to become dark matter hunters for a day,” Cooley said. “Explore your campus in the search for dark matter rocks, just as physicists are exploring the cosmos in the hunt for the nature of dark matter itself.”

Anyone who discovers a dark matter rock on the SMU campus is encouraged to grab their phone and snap a selfie with their rock. Tweet and tag your selfie #SMUDarkMatter so that @SMU, @SMUResearch and @SMUPhysics can retweet photos of the lucky finders.

As SMU’s resident dark matter scientist, Cooley is part of the 100-person international SuperCDMS SNOLAB experiment, which uses ultra pure materials and highly sensitive custom-built detectors to listen for the passage of dark matter.

SuperCDMS, an acronym for Super Cryogenic Dark Matter Search, resides at SNOLAB, an existing underground science laboratory in Ontario, Canada. Located deep underground, SNOLAB allows scientists to use the earth as a shield to block out particles that resemble dark matter, making it easier to see the real thing.

The SuperCDMS SNOLAB experiment, expected to be operational in 2020, has been designed to go deeper below the surface of the earth than earlier generations of the research.

“Dark matter experiments have been a smashing success — they’ve progressed farther than anyone anticipated. The SuperCDMS SNOLAB experiment is quite unique,” Cooley said. “It will allow us to probe models that predict dark matter with the tiniest masses.”

For more on Cooley’s research, go to “Hunt for dark matter takes physicists deep below earth’s surface, where WIMPS can’t hide.“ — Margaret Allen, SMU

Dark Matter Day events at SMU:

  • Sunday, Oct. 29, 4 p.m., McCord Auditorium — Maruša Bradač, Associate Professor at the University of California at Davis, will give a public lecture on dark matter. A reception will follow the lecture from 5 p.m. to 6 p.m. in the Dallas Hall Rotunda with beverages and light snacks. This event is free and open to the public, and is designed to be open to the widest possible audience.
  • Monday, Oct. 30, 4 p.m., Fondren Science Building, Room 158 — SMU Associate Professor Jodi Cooley will present a seminar on the SuperCDMS direct-detection dark matter search experiment. This event is part of the Physics Department Speaker Series. While this event is open to the public, it will be a more technical talk and may appeal more to an audience interested in the STEM areas of science, technology, engineering and mathematics, especially physics and astrophysics.
  • Tuesday, Oct. 31, 9 a.m. – 4 p.m., SMU Main Campus, Dark Matter Rock Hunt — The SMU Department of Physics has hidden “dark matter rocks” all across the SMU main campus. If you discover one of the dark matter rocks, bring it to the main office of the Physics Department, Fondren Science Building, Room 102, and get a special prize. All SMU students, faculty, staff and community members are welcome to join in the search.
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Study: New simple method determines rate at which we burn calories walking uphill, downhill, and on level ground

New method uses three variables of speed, load carried and slope to improve on the accuracy of existing standards for predicting how much energy people require for walking — a method beneficial to many, including military strategists to model mission success

When military strategists plan a mission, one of many factors is the toll it takes on the Army’s foot soldiers.

A long march and heavy load drains energy. So military strategists are often concerned with the calories a soldier will burn, and the effect of metabolic stress on their overall physiological status, including body temperature, fuel needs and fatigue.

Now scientists at Southern Methodist University, Dallas, have discovered a new more accurate way to predict how much energy a soldier uses walking.

The method was developed with funding from the U.S. military. It significantly improves on two existing standards currently in use, and relies on just three readily available variables.

An accurate quantitative assessment tool is important because the rate at which people burn calories while walking can vary tenfold depending on how fast they walk, if they carry a load, and whether the walk is uphill, downhill or level.

“Our new method improves on the accuracy of the two leading standards that have been in use for nearly 50 years,” said exercise physiologist Lindsay W. Ludlow, an SMU post-doctoral fellow and lead author on the study. “Our model is fairly simple and improves predictions.”

The research is part of a larger load carriage initiative undertaken by the U.S. Army Medical Research and Materiel Command. The average load carried by light infantry foot soldiers in Afghanistan in April and May 2003 was 132 pounds, according to a U.S. Army Borden Institute report.

“Soldiers carry heavy loads, so quantitative information on the consequences of load is critical for many reasons, from planning a route to evaluating the likelihood of mission success,” said SMU biomechanist and physiologist Peter Weyand, @Dr_Weyand.

“The military uses a variety of approaches to model, predict and monitor foot-soldier status and performance, including having soldiers outfitted with wearable devices,” Weyand said. “There is a critical need with modern foot soldiers to understand performance from the perspective of how big a load they are carrying.”

Weyand is senior author on the research and directs the Locomotor Performance Laboratory in the SMU Simmons School of Education, where subjects for the study were tested.

The researchers call their new method the “Minimum Mechanics Model” to reflect that it requires only three basic and readily available inputs to deliver broad accurate predictions. They report their findings in “Walking economy is predictably determined by speed, grade and gravitational load” in the Journal of Applied Physiology.

The necessary variables are the walker’s speed, the grade or slope of the walking surface, and the total weight of the body plus any load the walker is carrying.

“That’s all it takes to accurately predict how much energy a walker burns,” Ludlow said.

While the measurement is a critical one for foot soldiers, it’s also useful for hikers, backpackers, mall-walkers and others who are calorie conscious and may rely on wearable electronic gadgets to track the calories they burn, she said.

Muscle and gait mechanics tightly coupled across speed, grade, load
Existing standards now in use rely on the same three variables, but differently, and with less accuracy and breadth.

The new theory is a departure from the prevailing view that the mechanics of walking are too complex to be both simple and accurate.

“Ultimately, we found that three remarkably simple mechanical variables can provide predictive accuracy across a broad range of conditions,” Ludlow said. “The accuracy achieved provides strong indirect evidence that the muscular activity determining calorie-burn rates during walking is tightly coupled to the speed, surface inclination and total weight terms in our model.”

By using two different sets of research subjects, the researchers independently evaluated their model’s ability to accurately predict the amount of energy burned.

“If muscle and gait mechanics were not tightly coupled across speed, grade and load, the level of predictive accuracy we achieved is unlikely,” Weyand said.

First generalized equation developed directly from a single, large database
The two existing equations that have been the working standards for nearly 50 years were necessarily based on just a few subjects and a limited number of data points.

One standard from the American College of Sports Medicine tested only speed and uphill grades, with its first formulation being based on data from only three individuals.

The other standard, commonly referred to as the Pandolf equation is used more frequently by the military and relies heavily on data from six soldiers combined with earlier experimental results.

In contrast, the generalized equation from SMU was derived from what is believed to be the largest database available for human walking metabolism.

The SMU study tested 32 adult subjects individually under 90 different speed-grade and load conditions on treadmills at the SMU Locomotor Performance Laboratory, @LocomotorLabSMU.

“The leading standardized equations included only level and uphill inclinations,” Weyand said. “We felt it was important to also provide downhill capabilities since soldiers in the field will encounter negative inclines as frequently as positive ones.”

Subjects fast prior to measuring their resting metabolic rates
Another key element of the SMU lab’s Minimum Mechanics Model is the quantitative treatment of resting metabolic rate.

“To obtain true resting metabolic rate, we had subjects fast for 8 to 12 hours prior to measuring their resting metabolic rates in the early morning,” Ludlow said. “Once at the lab, they laid down for an hour while the researchers measured their resting metabolic rate.”

In separate test sessions, the subjects walked on the treadmill for dozens of trials lasting five minutes each, wearing a mouthpiece and nose clip. In the last two minutes of each trial, the researchers measured steady-state rates of oxygen uptake to determine the rate at which each subject was burning energy.

Adults in one group of 20 subjects were each measured walking without a load at speeds of 0.4 meters per second, 0.7 meters per second, 1 meter per second, 1.3 meters per second and 1.6 meters per second on six different gradients: downhill grades of minus six degrees and minus three degrees; level ground; and uphill at inclines of three degrees, six degrees and nine degrees.

Adults in a second group of 20 were each tested at speeds of 0.6 meters per second, 1 meter per second and 1.4 meters per second on the same six gradients, but they carried loads that were 18 percent of body weight, and 31 percent of body weight.

Walking metabolic rates increased in proportion to increased load
As expected, walking metabolic rates increased in direct proportion to the increase in load, and largely in accordance with support force requirements across both speed and grade, said Weyand and Ludlow.

Weyand is Glenn Simmons Professor of Applied Physiology and professor of biomechanics in the Department of Applied Physiology and Wellness in SMU’s Annette Caldwell Simmons School of Education and Human Development. He also is lead scientist for the biomechanics and modeling portion of the Sub-2-Hour marathon project, an international research consortium based in the United Kingdom. — Margaret Allen, SMU

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Prehistoric humans formed complex mating networks to avoid inbreeding

An individual buried at Snugger, whose remains were some of those whose complete genomes were sequenced. (Credit: Libor Balák, Anthropark)

A new study has sequenced the genomes of individuals from an ancient burial site in Russia and discovered that they were, at most, first cousins, indicating that they had developed sexual partnerships beyond their immediate social and family group.

A new study has identified when humans transitioned from simple systems designed to minimize inbreeding to more complex ones suitable for hunter-gatherer societies.

The study findings are reported in the journal Science and demonstrate that, by at least 34,000 years ago, human hunter-gatherer groups had developed sophisticated social and mating networks that minimized inbreeding.

The study examined genetic information from the remains of modern humans who lived during the early part of the Upper Palaeolithic, a period when modern humans from Africa first colonized western Eurasia, eventually displacing the Neanderthals who lived there before.

The results suggest that people deliberately sought partners beyond their immediate family, and that they were probably connected to a wider network of groups from within which mates were chosen, thus avoiding inbreeding.

The research was carried out by an international team of academics, led by the University of Cambridge, U.K., and the University of Copenhagen, Denmark. The team included SMU archaeologist David J. Meltzer, whose expertise includes the First People in the Americas.

The researchers sequenced the genomes of four individuals from Sunghir, a famous Upper Palaeolithic site in Russia, which was inhabited about 34,000 years ago.

The article, “Ancient genomes show social and reproductive behavior of early Upper Paleolithic foragers,” is published in the Oct. 5, 2017 issue of Science.

Complex mating systems may partly explain modern human survival
Among recent hunter-gatherers, the exchange of mates between groups is embedded into a cultural system of rules, ceremonies and rituals. The symbolism, complexity and time invested in the extraordinarily rich objects and jewellery found in the Sunghir burials, as well as the burials themselves, suggest that these early human societies symbolically marked major events in the life of individuals and their community in ways that foreshadow modern rituals and ceremonies — birth, marriage, death, shared ancestry, shared cultures.

The study’s authors also hint that the early development of more complex mating systems may at least partly explain why modern humans proved successful while other, rival species, such as Neanderthals, did not. More ancient genomic information from both early humans and Neanderthals is needed to test this idea.

The human fossils buried at Sunghir are a unique source of information about early modern human societies of western Eurasia. Sunghir preserves two contemporaneous burials – that of an adult man, and that of two children buried together and which includes the symbolically modified remains of another adult.

To the researchers’ surprise, however, these individuals were not closely related in genetic terms; at the very most, they were second cousins. This is true even for the two children who were buried head-to-head in the same grave.

“What this means is that people in the Upper Palaeolithic, who were living in tiny groups, understood the importance of avoiding inbreeding,” said Eske Willerslev, a professor at St John’s College and the University of Copenhagen, who was senior author on the study. “The data that we have suggest that it was being purposely avoided. This means that they must have developed a system for this purpose. If the small hunter and gathering bands were mixing at random, we would see much greater evidence of inbreeding than we have here.”

Early human societies changed ancestral mating system
The small family bands were likely interconnected within larger networks, facilitating the exchange of peoples between bands in order to maintain diversity, said Martin Sikora, a professor at the Centre for GeoGenetics at the University of Copenhagen.

Most non-human primate societies are organized around single-sex kin (matrilines or patrilines), where one of the sexes remains resident and the other migrates to another group, thus minimizing inbreeding. At some point, early human societies changed the ancestral mating system into one in which a large number of the individuals that form small resident/foraging units are non-kin, where the relations among units that exchange mating partners are formalized through complex cultural systems.

In at least one Neanderthal case, an individual from the Altai Mountains who died about 50,000 years ago, inbreeding was not avoided, suggesting that the modern human cultural systems that allows to decouple the size of the resident community from the danger of inbreeding was not in place. This leads the researchers to speculate that an early, systematic approach to preventing inbreeding may have helped modern humans to thrive in relation to with other hominins.

This should be treated with caution, however.

“We don’t know why the Altai Neanderthal groups were inbred,” Sikora said. “Maybe they were isolated and that was the only option; or maybe they really did fail to develop a network of connections. We will need more genomic data of diverse Neanderthal populations to be sure.”

Upper Palaeolithic human groups sustained very small group sizes
The researchers were able to sequence the complete genomes of all four individuals found within the two graves at Sunghir. These data were compared with information on both modern and ancient human genomes from across the world.

They found that the four individuals studied were genetically no closer than second cousins, while the adult femur filled with red ochre found in the youngsters’ grave would have belonged to an individual no closer than great-great grandfather of the boys. “This goes against what many would have predicted,” Willerslev said. “I think many researchers had assumed that the people of Sunghir were very closely related, especially the two youngsters from the same grave.”

The people at Sunghir may have been part of a network similar to that of modern day hunter-gatherers, such as Aboriginal Australians and some historical Native American societies. Like their Upper Palaeolithic ancestors, these societies lived in fairly small groups of some 25 people, but they were also connected to a larger community of perhaps 200 people, within which there were rules governing with whom individuals can form partnerships.

“The results from Sunghir show that Upper Palaeolithic human groups could sustain very small group sizes by embedding them in a wide social network of other groups maintained by sophisticated cultural systems,” said Marta Mirazón Lahr, a professor at the University of Cambridge.

Willerslev also highlights a possible link with the unusual sophistication of the ornaments and cultural objects found at Sunghir. Such band-specific cultural expressions may have been used to signal who are “we” versus who are “they,” and thus a means of reinforcing a shared identity built on marriage exchange across foraging units. The number and sophistication of personal ornaments and artefacts found at Sunghir are exceptional even among other modern human burials, and not found among Neanderthals and other hominins.

“The ornamentation is incredible and there is no evidence of anything like that with other hominins,” Willerslev added. “When you put the evidence together, it seems to be telling us about the really big questions: what made these people who they were as a species, and who we are as a result.”

Ancient genomics throw light on aspects of social life
These results show the power of ancient genomics to throw light on aspects of social life among early humans, and pave the way for further studies to explore variation in social and demographic strategies in prehistoric socieities.

“Much of human evolution is about changes in our social and cultural behavior, and the impact this has had on our success as a species. This study takes us a step further toward pinpointing when and why the things that make humans unique evolved,” said Robert Foley, a professor at the University of Cambridge.

Meltzer is Henderson-Morrison Professor of Prehistory in the SMU Department of Anthropology in Dedman College. As a scientist who studies how people first came to inhabit North America, Meltzer in 2009 was elected a member of the National Academy of Sciences in recognition for his achievements in original scientific research. In 2013 he was elected to the American Academy of Arts and Sciences. — University of Cambridge, SMU

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A composite window into human history

Excavated dwellings in the stone-built Neolithic settlement of Skara Brae in the Orkney archipelago of Scotland. (John Burka)

Better integration of ancient DNA studies with archaeology promises deeper insights.

DNA testing alone of ancient human remains can’t resolve questions about past societies.

It’s time for geneticists and archaeologists to collaborate more fully in the face of ever greater advancements in ancient DNA research, according to SMU archaeologist David J. Meltzer and his colleagues in a recent article in the scientific journal Science.

The authors write in “A composite window into human history” that over the past decade, DNA testing of ancient human remains has become a valuable tool for studying and understanding past human population histories.

Most notably, for example, is how sequencing of ancient genomes resolved the dispute over our species’ evolutionary relationship with Neanderthals, the authors point out.

Even so, the authors caution that collaboration with archaeologists is key for scientific accuracy as well as navigating ethical implications.

Archaeologists know from the study of artifacts that it isn’t always the case that people who share material culture traits were likewise part of the same biological population.

“One can have similar traits without relatedness, and relatedness without similarity in traits,” say the authors in the article.

At the same time, where there is biological relatedness, cultural relatedness can’t be assumed, nor can language groups indicate that biological populations, material assemblages or even social units are related.

“Geneticists are often keen to use ancient DNA to understand the causes and mechanisms of demographic and cultural change,” the authors write. “But archaeologists long ago abandoned the idea that migrations or encounters between populations are a necessary or sufficient explanation of cultural change.”

The authors make the point that understanding population movements requires broad investigation of many factors, including environmental and social contexts, timing and logistics, how new resources and landscapes were managed, and the transfer of cultural knowledge.

“Hence, it requires evidence for archaeology, paleoecology and other fields to supplement and complement ancient DNA data,” the authors write. “And that entails effective collaboration, one that goes beyond archaeologists serving as passive sample providers.”

Meltzer is Henderson-Morrison Professor of Prehistory in the SMU Department of Anthropology in Dedman College. As a scientist who studies how people first came to inhabit North America, Meltzer in 2009 was elected a member of the National Academy of Sciences in recognition for his achievements in original scientific research. In 2013 he was elected to the American Academy of Arts and Sciences.

Co-authors on the perspective piece with Meltzer were Niels N. Johannsen, Aarhus University, Denmark; Greger Larson, University of Oxford; and Marc Vader Linden, University College London.

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$2.5 million NSF grant gives teachers a math assessment tool to help students

New assessment tool for teachers to measure math reasoning skills can drive effort to intervene early in ongoing struggles of U.S. elementary and high school students

A $2.5 million grant from the National Science Foundation to researchers at Southern Methodist University, Dallas, targets the ongoing struggle of U.S. elementary and high school students with math.

When it comes to the STEM fields of science, technology, engineering and math, research shows that U.S. students continue at a disadvantage all the way through high school and entering college.

The four-year NSF grant to the Annette Caldwell Simmons School of Education and Human Development is led by SMU K-12 math education experts Leanne Ketterlin Geller and Lindsey Perry. They will conduct research and develop an assessment system comprised of two universal screening tools to measure mathematical reasoning skills for grades K–2.

“This is an opportunity to develop an assessment system that can help teachers support students at the earliest, and arguably one of the most critical, phases of a child’s mathematical development,” said Ketterlin Geller, a professor in the Simmons School and principal investigator for the grant developing the “Measures of Mathematical Reasoning Skills” system.

Teachers and schools will use the assessment system to screen students and determine who is at risk for difficulty in early mathematics, including students with disabilities. The measures also will help provide important information about the intensity of support needed for a given student.

Few assessments are currently available to measure the critical math concepts taught during those early school years, Ketterlin Geller said.

“Providing teachers with data to understand how a child processes these concepts can have a long-term impact on students’ success not only in advanced math like algebra, but also success in STEM fields, such as chemistry, biology, geology and engineering,” she said.

Early math a better predictor of future learning
A 2015 Mathematics National Assessment of Education Progress report found that only 40 percent of U.S. fourth-grade students were classified as proficient or advanced, and those numbers have not improved between 2009 and 2015. In fact, the geometry scale of the fourth-grade mathematics report was significantly lower in 2015 than in 2009.

Early mathematics is a better and more powerful predictor of future learning, including reading and mathematics achievement, compared to early reading ability or other factors such as attention skills, according to one 2007 study on school readiness.

Research also has found that students’ early mathematics knowledge is a more powerful predictor of their future socioeconomic status at age 42 than their family’s socioeconomic status as children.

Early mathematics comprises numerous skills. However, number sense — the ability to work with numbers flexibly — in addition to spatial sense — the ability to understand the complexity of one’s environment — are consistently identified as two of the main components that should be emphasized in early mathematics standards and instruction, say the SMU researchers.

The Measures of Mathematical Reasoning Skills system will contain tests for both numeric relational reasoning and spatial reasoning.

Universal screening tools focused on these topics do not yet exist
“I’m passionate about this research because students who can reason spatially and relationally with numbers are better equipped for future mathematics courses, STEM degrees and STEM careers,” said Perry, whose doctoral dissertation for her Ph.D. from SMU in 2016 specifically focused on those two mathematical constructs.

“While these are very foundational and predictive constructs, these reasoning skills have typically not been emphasized at these grade levels, and universal screening tools focused on these topics do not yet exist,” said Perry, who is co-principal investigator.

“Since intervention in the early elementary grades can significantly improve mathematics achievement, it is critical that K-2 teachers have access to high-quality screening tools to help them with their intervention efforts,” she said. “We feel that the Measures of Mathematical Reasoning Skills system can really make a difference for K-2 teachers as they prepare the next generation of STEM leaders.”

The four-year project, Measuring Early Mathematical Reasoning Skills: Developing Tests of Numeric Relational Reasoning and Spatial Reasoning, started Sept. 15, 2017. It employs an iterative research design for developing formative assessments, a process that Ketterlin Geller has devoted much of her 20-year career to.

Ketterlin Geller is Texas Instruments Endowed Chair in Education and director of Research in Mathematics Education in SMU’s Annette Caldwell Simmons School of Education and Human Development. She is also a Fellow with the Caruth Institute for Engineering Education in the Lyle School of Engineering.