Tag: David Meltzer

Textbook theory of how humans populated America is “biologically unviable,” study finds

Post author By Margaret Allen
Post date August 10, 2016

Using ancient DNA, researchers have created a unique picture of how a prehistoric migration route evolved over thousands of years – revealing that it could not have been used by the first people to enter the Americas, as traditionally thought.

The established theory about how Ice Age peoples first reached the present-day United States has been challenged by an unprecedented study that concludes that their supposed entry route was “biologically unviable.”

The first people to reach the Americas crossed via an ancient land bridge between Siberia and Alaska but then, according to conventional wisdom, had to wait until two huge ice sheets that covered what is now Canada started to recede, creating the so-called “ice-free corridor” that enabled them to move south.

In a new study published in the journal Nature, however, an international team of researchers used ancient DNA extracted from a crucial pinch-point within this corridor to investigate how its ecosystem evolved as the glaciers began to retreat.

They created a comprehensive picture showing how and when different flora and fauna emerged so the once ice-covered landscape became a viable passageway. No prehistoric reconstruction project like this has ever been attempted before.

Present day view south in Canada's Peace River drainage basin where retreating ice sheets created an ice-free corridor more than 13,000 years ago. (Mikkel Winther Pedersen, University of Copenhagen) — Present day view south in Canada’s Peace River drainage basin where retreating ice sheets created an ice-free corridor more than 13,000 years ago. (Mikkel Winther Pedersen, University of Copenhagen)

The researchers conclude that while people may well have travelled this corridor after about 12,600 years ago, it would have been impassable earlier than that, as the corridor lacked crucial resources, such as wood for fuel and tools, as well as game animals essential to the hunter-gatherer lifestyle.

If this is true, then it means that the first Americans, who were present south of the ice sheets long before 12,600 years ago, must have made the journey south by another route. The study’s authors suggest that they probably migrated along the Pacific coast.

Who these people were is still widely disputed. Archaeologists agree, however, that early inhabitants of the modern-day contiguous United States included the so-called “Clovis” culture, which first appear in the archaeological record over 13,000 years ago. And the new study argues that the ice-free corridor would have been completely impassable at that time.

“There is compelling evidence that Clovis was preceded by an earlier and possibly separate population,” said archaeologist and co-author on the study David J. Meltzer, Henderson-Morrison Professor of Prehistory in the Department of Anthropology at Southern Methodist University, Dallas. “But either way, the first people to reach the Americas in Ice Age times would have found the corridor itself impassable.”

The ice-free corridor simply opened up too late to be the principal entry route
The research was led by evolutionary geneticist Eske Willerslev, a Fellow of St John’s College, University of Cambridge, who also holds posts at the Centre for GeoGenetics, University of Copenhagen, and the Wellcome Sanger Institute in Cambridge.

“The bottom line is that even though the physical corridor was open by 13,000 years ago, it was several hundred years before it was possible to use it,” Willerslev said. “That means that the first people entering what is now the U.S., Central and South America must have taken a different route. Whether you believe these people were Clovis, or someone else, they simply could not have come through the corridor, as long claimed.”

Mikkel Winther Pedersen, a doctoral student at the Centre for GeoGenetics, University of Copenhagen, who conducted the molecular analysis, added: “The ice-free corridor was long considered the principal entry route for the first Americans. Our results reveal that it simply opened up too late for that to have been possible.”

The corridor is thought to have been about 1,500 kilometers long, and emerged east of the Rocky Mountains 13,000 years ago in present-day western Canada, as two great ice sheets – the Cordilleran and Laurentide, retreated.

On paper, this fits well with the argument that Clovis people were the first to disperse across the Americas. The first evidence for this culture, which is named after distinctive stone tools found near Clovis, New Mexico, also dates from roughly the same time, although many archaeologists now believe that other people arrived earlier.

“What nobody has looked at is when the corridor became biologically viable,” Willerslev said. “When could they actually have survived the long and difficult journey through it?”

Radiocarbon dates, pollen, macrofossils and DNA revealed how ecosystem developed
The conclusion reached by Willerslev and his colleagues is that the journey would have been impossible until about 12,600 years ago. Their research focused on a “bottleneck,” one of the last parts of the corridor to become ice-free, and now partly covered by Charlie Lake in British Columbia, and Spring Lake, Alberta — both part of Canada’s Peace River drainage basin.

The team gathered evidence — including radiocarbon dates, pollen, macrofossils and DNA taken from lake sediment cores — which they obtained standing on the frozen lake surface during the winter season. Willerslev’s own PhD, 13 years ago, demonstrated that it is possible to extract ancient plant and mammalian DNA from sediments, as it contains preserved molecular fossils from substances such as tissue, urine and feces.

Having acquired the DNA, the group then applied a technique termed “shotgun sequencing.”

“Instead of looking for specific pieces of DNA from individual species, we basically sequenced everything in there, from bacteria to animals,” Willerslev said. “It’s amazing what you can get out of this. We found evidence of fish, eagles, mammals and plants. It shows how effective this approach can be to reconstruct past environments.”

This approach allowed the team to see, with remarkable precision, how the bottleneck’s ecosystem developed. Crucially, it showed that before about 12,600 years ago, there were no plants, nor animals, in the corridor, meaning that humans passing through it would not have had resources vital to survive.

Clovis could not have travelled through ice-free corridor as previously believed
Around 12,600 years ago, steppe vegetation started to appear, followed quickly by animals such as bison, woolly mammoth, jackrabbits and voles. Importantly 11,500 years ago, the researchers identified a transition to a “parkland ecosystem” – a landscape densely populated by trees, as well as moose, elk and bald-headed eagles, which would have offered crucial resources for migrating humans.

Somewhere in between, the lakes in the area were populated by fish, including several identifiable species such as pike and perch. Finally, about 10,000 years ago, the area transitioned again, this time into boreal forest, characterized by spruce and pine.

The fact that Clovis was clearly present south of the corridor before 12,600 years ago means that they could not have travelled through it.

“Most likely, you would say that the evidence points to their having travelled down the Pacific Coast,” Willerslev added. “That now seems the most likely scenario.”

The paper, “Postglacial viability and colonization in North America’s ice-free corridor,” is published online ahead of print in Nature on Aug. 10, 2016.

Tags David Meltzer, Dedman College, Featurette, SMU Department of Anthropology

Culture, Society & Family Earth & Climate Economics & Statistics Energy & Matter Events Fossils & Ruins Health & Medicine Learning & Education Mind & Brain Plants & Animals Researcher news Student researchers

SMU 2015 research efforts broadly noted in a variety of ways for world-changing impact

Post author By Margaret Allen
Post date January 8, 2016

SMU scientists and their research have a global reach that is frequently noted, beyond peer publications and media mentions.

By Margaret Allen
SMU News & Communications
It was a good year for SMU faculty and student research efforts. Here is a small sampling of public and published acknowledgements during 2015:

Hot topic merits open access
Taylor & Francis, publisher of the online journal Environmental Education Research, lifted its subscription-only requirement to meet demand for an article on how climate change is taught to middle-schoolers in California.

Co-author of the research was Diego Román, assistant professor in the Department of Teaching and Learning, Annette Caldwell Simmons School of Education and Human Development.

Román’s research revealed that California textbooks are teaching sixth graders that climate change is a controversial debate stemming from differing opinions, rather than a scientific conclusion based on rigorous scientific evidence.

The article, “Textbooks of doubt: Using systemic functional analysis to explore the framing of climate change in middle-school science textbooks,” published in September. The finding generated such strong interest that Taylor & Francis opened access to the article.

Research makes the cover of Biochemistry
Drugs important in the battle against cancer were tested in a virtual lab by SMU biology professors to see how they would behave in the human cell.

A computer-generated composite image of the simulation made the Dec. 15 cover of the journal Biochemistry.

Scientific articles about discoveries from the simulation were also published in the peer review journals Biochemistry and in Pharmacology Research & Perspectives.

The researchers tested the drugs by simulating their interaction in a computer-generated model of one of the cell’s key molecular pumps — the protein P-glycoprotein, or P-gp. Outcomes of interest were then tested in the Wise-Vogel wet lab.

The ongoing research is the work of biochemists John Wise, associate professor, and Pia Vogel, professor and director of the SMU Center for Drug Discovery, Design and Delivery in Dedman College. Assisting them were a team of SMU graduate and undergraduate students.

The researchers developed the model to overcome the problem of relying on traditional static images for the structure of P-gp. The simulation makes it possible for researchers to dock nearly any drug in the protein and see how it behaves, then test those of interest in an actual lab.

To date, the researchers have run millions of compounds through the pump and have discovered some that are promising for development into pharmaceutical drugs to battle cancer.

Click here to read more about the research.

SMU, Simpson Rowe, sexual assault, video

Strong interest in research on sexual victimization
Teen girls were less likely to report being sexually victimized after learning to assertively resist unwanted sexual overtures and after practicing resistance in a realistic virtual environment, according to three professors from the SMU Department of Psychology.

The finding was reported in Behavior Therapy. The article was one of the psychology journal’s most heavily shared and mentioned articles across social media, blogs and news outlets during 2015, the publisher announced.

The study was the work of Dedman College faculty Lorelei Simpson Rowe, associate professor and Psychology Department graduate program co-director; Ernest Jouriles, professor; and Renee McDonald, SMU associate dean for research and academic affairs.

The journal’s publisher, Elsevier, temporarily has lifted its subscription requirement on the article, “Reducing Sexual Victimization Among Adolescent Girls: A Randomized Controlled Pilot Trial of My Voice, My Choice,” and has opened it to free access for three months.

Click here to read more about the research.

Consumers assume bigger price equals better quality
Even when competing firms can credibly disclose the positive attributes of their products to buyers, they may not do so.

Instead, they find it more lucrative to “signal” quality through the prices they charge, typically working on the assumption that shoppers think a high price indicates high quality. The resulting high prices hurt buyers, and may create a case for mandatory disclosure of quality through public policy.

That was a finding of the research of Dedman College’s Santanu Roy, professor, Department of Economics. Roy’s article about the research was published in February in one of the blue-ribbon journals, and the oldest, in the field, The Economic Journal.

Published by the U.K.’s Royal Economic Society, The Economic Journal is one of the founding journals of modern economics. The journal issued a media briefing about the paper, “Competition, Disclosure and Signaling,” typically reserved for academic papers of broad public interest.

Chemistry research group edits special issue
Chemistry professors Dieter Cremer and Elfi Kraka, who lead SMU’s Computational and Theoretical Chemistry Group, were guest editors of a special issue of the prestigious Journal of Physical Chemistry. The issue published in March.

The Computational and Theoretical research group, called CATCO for short, is a union of computational and theoretical chemistry scientists at SMU. Their focus is research in computational chemistry, educating and training graduate and undergraduate students, disseminating and explaining results of their research to the broader public, and programming computers for the calculation of molecules and molecular aggregates.

The special issue of Physical Chemistry included 40 contributions from participants of a four-day conference in Dallas in March 2014 that was hosted by CATCO. The 25th Austin Symposium drew 108 participants from 22 different countries who, combined, presented eight plenary talks, 60 lectures and about 40 posters.

CATCO presented its research with contributions from Cremer and Kraka, as well as Marek Freindorf, research assistant professor; Wenli Zou, visiting professor; Robert Kalescky, post-doctoral fellow; and graduate students Alan Humason, Thomas Sexton, Dani Setlawan and Vytor Oliveira.

There have been more than 75 graduate students and research associates working in the CATCO group, which originally was formed at the University of Cologne, Germany, before moving to SMU in 2009.

Vertebrate paleontology recognized with proclamation
Dallas Mayor Mike Rawlings proclaimed Oct. 11-17, 2015 Vertebrate Paleontology week in Dallas on behalf of the Dallas City Council.

The proclamation honored the 75th Annual Meeting of the Society of Vertebrate Paleontology, which was jointly hosted by SMU’s Roy M. Huffington Department of Earth Sciences in Dedman College and the Perot Museum of Science and Nature. The conference drew to Dallas some 1,200 scientists from around the world.

Making research presentations or presenting research posters were: faculty members Bonnie Jacobs, Louis Jacobs, Michael Polcyn, Neil Tabor and Dale Winkler; adjunct research assistant professor Alisa Winkler; research staff member Kurt Ferguson; post-doctoral researchers T. Scott Myers and Lauren Michael; and graduate students Matthew Clemens, John Graf, Gary Johnson and Kate Andrzejewski.

The host committee co-chairs were Anthony Fiorillo, adjunct research professor; and Louis Jacobs, professor. Committee members included Polcyn; Christopher Strganac, graduate student; Diana Vineyard, research associate; and research professor Dale Winkler.

KERA radio reporter Kat Chow filed a report from the conference, explaining to listeners the science of vertebrate paleontology, which exposes the past, present and future of life on earth by studying fossils of animals that had backbones.

SMU earthquake scientists rock scientific journal

Modelled pressure changes caused by injection and production. (Nature Communications/SMU)

Findings by the SMU earthquake team reverberated across the nation with publication of their scientific article in the prestigious British interdisciplinary journal Nature, ranked as one of the world’s most cited scientific journals.

The article reported that the SMU-led seismology team found that high volumes of wastewater injection combined with saltwater extraction from natural gas wells is the most likely cause of unusually frequent earthquakes occurring in the Dallas-Fort Worth area near the small community of Azle.

The research was the work of Dedman College faculty Matthew Hornbach, associate professor of geophysics; Heather DeShon, associate professor of geophysics; Brian Stump, SMU Albritton Chair in Earth Sciences; Chris Hayward, research staff and director geophysics research program; and Beatrice Magnani, associate professor of geophysics.

The article, “Causal factors for seismicity near Azle, Texas,” published online in late April. Already the article has been downloaded nearly 6,000 times, and heavily shared on both social and conventional media. The article has achieved a ranking of 270, which puts it in the 99th percentile of 144,972 tracked articles of a similar age in all journals, and 98th percentile of 626 tracked articles of a similar age in Nature.

“It has a very high impact factor for an article of its age,” said Robert Gregory, professor and chair, SMU Earth Sciences Department.

The scientific article also was entered into the record for public hearings both at the Texas Railroad Commission and the Texas House Subcommittee on Seismic Activity.

Researchers settle long-debated heritage question of “The Ancient One”

The skull of Kennewick Man and a sculpted bust by StudioEIS based on forensic facial reconstruction by sculptor Amanda Danning. (Credit: Brittany Tatchell)

The research of Dedman College anthropologist and Henderson-Morrison Professor of Prehistory David Meltzer played a role in settling the long-debated and highly controversial heritage of “Kennewick Man.”

Also known as “The Ancient One,” the 8,400-year-old male skeleton discovered in Washington state has been the subject of debate for nearly two decades. Argument over his ancestry has gained him notoriety in high-profile newspaper and magazine articles, as well as making him the subject of intense scholarly study.

Officially the jurisdiction of the U.S. Army Corps of Engineers, Kennewick Man was discovered in 1996 and radiocarbon dated to 8500 years ago.

Because of his cranial shape and size he was declared not Native American but instead ‘Caucasoid,’ implying a very different population had once been in the Americas, one that was unrelated to contemporary Native Americans.

But Native Americans long have claimed Kennewick Man as theirs and had asked for repatriation of his remains for burial according to their customs.

Meltzer, collaborating with his geneticist colleague Eske Willerslev and his team at the Centre for GeoGenetics at the University of Copenhagen, in June reported the results of their analysis of the DNA of Kennewick in the prestigious British journal Nature in the scientific paper “The ancestry and affiliations of Kennewick Man.”

The results were announced at a news conference, settling the question based on first-ever DNA evidence: Kennewick Man is Native American.

The announcement garnered national and international media attention, and propelled a new push to return the skeleton to a coalition of Columbia Basin tribes. Sen. Patty Murray (D-WA) introduced the Bring the Ancient One Home Act of 2015 and Washington Gov. Jay Inslee has offered state assistance for returning the remains to Native Tribes.

Science named the Kennewick work one of its nine runners-up in the highly esteemed magazine’s annual “Breakthrough of the Year” competition.

The research article has been viewed more than 60,000 times. It has achieved a ranking of 665, which puts it in the 99th percentile of 169,466 tracked articles of a similar age in all journals, and in the 94th percentile of 958 tracked articles of a similar age in Nature.

In “Kennewick Man: coming to closure,” an article in the December issue of Antiquity, a journal of Cambridge University Press, Meltzer noted that the DNA merely confirmed what the tribes had known all along: “We are him, he is us,” said one tribal spokesman. Meltzer concludes: “We presented the DNA evidence. The tribal members gave it meaning.”

Click here to read more about the research.

Prehistoric vacuum cleaner captures singular award

Paleontologists Louis L. Jacobs, SMU, and Anthony Fiorillo, Perot Museum, have identified a new species of marine mammal from bones recovered from Unalaska, an Aleutian island in the North Pacific. (Hillsman Jackson, SMU)

Science writer Laura Geggel with Live Science named a new species of extinct marine mammal identified by two SMU paleontologists among “The 10 Strangest Animal Discoveries of 2015.”

The new species, dubbed a prehistoric hoover by London’s Daily Mail online news site, was identified by SMU paleontologist Louis L. Jacobs, a professor in the Roy M. Huffington Department of Earth Sciences, Dedman College of Humanities and Sciences, and paleontologist and SMU adjunct research professor Anthony Fiorillo, vice president of research and collections and chief curator at the Perot Museum of Nature and Science.

Jacobs and Fiorillo co-authored a study about the identification of new fossils from the oddball creature Desmostylia, discovered in the same waters where the popular “Deadliest Catch” TV show is filmed. The hippo-like creature ate like a vacuum cleaner and is a new genus and species of the only order of marine mammals ever to go extinct — surviving a mere 23 million years.

Desmostylians, every single species combined, lived in an interval between 33 million and 10 million years ago. Their strange columnar teeth and odd style of eating don’t occur in any other animal, Jacobs said.

SMU campus hosted the world’s premier physicists

The SMU Department of Physics hosted the “23rd International Workshop on Deep Inelastic Scattering and Related Subjects” from April 27-May 1, 2015. Deep Inelastic Scattering is the process of probing the quantum particles that make up our universe.

As noted by the CERN Courier — the news magazine of the CERN Laboratory in Geneva, which hosts the Large Hadron Collider, the world’s largest science experiment — more than 250 scientists from 30 countries presented more than 200 talks on a multitude of subjects relevant to experimental and theoretical research. SMU physicists presented at the conference.

The SMU organizing committee was led by Fred Olness, professor and chair of the SMU Department of Physics in Dedman College, who also gave opening and closing remarks at the conference. The committee consisted of other SMU faculty, including Jodi Cooley, associate professor; Simon Dalley, senior lecturer; Robert Kehoe, professor; Pavel Nadolsky, associate professor, who also presented progress on experiments at CERN’s Large Hadron Collider; Randy Scalise, senior lecturer; and Stephen Sekula, associate professor.

Sekula also organized a series of short talks for the public about physics and the big questions that face us as we try to understand our universe.

Click here to read more about the research.

Tags Alan Humason, Alisa J. WInkler, Annette Caldwell Simmons School of Education and Human Development, Anthony Fiorillo, Beatrice Magnani, Bonnie F. Jacobs, Brian W. Stump, Chris Hayward, Christopher Strganac, Dale A. Winkler, Dani Setlawan, David Meltzer, Dedman College, Diana Vineyard, Diego Román, Dieter Creme, Elfi Kraka, Ernest Jouriles, Fredrick Olness, Gary Johnson, Heather R. DeShon, Jodi Cooley, John F. Graf, John Wise, Kate Andrzejewski, Kurt Ferguson, Lauren Michael, Lorelei Simpson Rowe, Louis L. Jacobs, Marek Freindorf, Matthew Clemens, Matthew J. Hornbach, Michael J. Polcyn, Neil Tabor, Pavel Nadolsky, Pia Vogel, Randy Scalise, Renee McDonald, Robert Gregory, Robert Kalescky, Robert Kehoe, Roy M. Huffington Department of Earth Sciences, Santanu Roy, Simon Dalley, SMU Department of Anthropology, SMU Department of Biological Sciences, SMU Department of Chemistry, SMU Department of Economics, SMU Department of Physics, SMU Department of Psychology, Stephen J. Sekula, Thomas Sexton, Timothy S. Myers, Vytor Oliveira, Wenli Zou

Culture, Society & Family Fossils & Ruins Researcher news SMU In The News

New York Times: Scientists Trace an Ancient DNA Link Between Amazonians and Australasians

Post author By Margaret Allen
Post date July 24, 2015

Karitiana children in their village near Porto Velho, Rondonia, Brazil. Scientists found that some people in the Brazilian Amazon have an ancient genetic tie to indigenous Australians, New Guineans and other Australasians. (Credit: New York Times)

New York Times reporter James Gorman interviewed SMU’s David Meltzer, a professor in the SMU Department of Anthropology in the Dedman College of Humanities and Sciences, about a new large genome-scale study that revealed that the ancestors of all present-day Native Americans arrived in the Americas as part of a single migration wave, no earlier than 23,000 years ago.

The finding addresses the ongoing debate over when and how many times the ancestors of present-day Native Americans entered the New World from Siberia.

Meltzer was a co-author on the study, which was conducted by an international team headed by the Centre for GeoGenetics at the University of Copenhagen. It published online July 23, 2015 in Science.

Meltzer’s research focus is on the origins, antiquity, and adaptations of the first Americans – Paleoindians – who colonized the North American continent at the end of the Ice Age. He focuses on how these hunter-gatherers met the challenges of moving across and adapting to the vast, ecologically diverse landscape of Late Glacial North America during a time of significant climate change.

His research has been supported by grants from the National Geographic Society, the National Science Foundation, The Potts and Sibley Foundation and the Smithsonian Institution. In 1996, he received a research endowment from Joseph and Ruth Cramer to establish the Quest Archaeological Research Program at SMU, which will support in perpetuity research on the earliest occupants of North America.

Meltzer is a member of the National Academy of Sciences and is Henderson-Morrison Professor of Prehistory in SMU’s Dedman College.

The New York Times article published July 21, 2015.

Read the full article, “Scientists Trace an Ancient DNA Link Between Amazonians and Australasians.”

EXCERPT:

By James Gorman
New York Times

Some people in the Brazilian Amazon are very distant relations of indigenous Australians, New Guineans and other Australasians, two groups of scientists who conducted detailed genetic analyses reported Tuesday. But the researchers disagree on the source of that ancestry.

The connection is ancient, all agree, and attributable to Eurasian migrants to the Americas who had some Australasian ancestry, the scientists said.

But one group said the evidence is clear that two different populations came from Siberia to settle the Americas 15,000 or more years ago. The other scientific team says there was only one founding population from which all indigenous Americans, except for the Inuit, descended and the Australasian DNA came later, and not through a full-scale migration. For instance, genes could have flowed through a kind of chain of intermarriage and mixing between groups living in the Aleutian Islands and down the Pacific Coast.

Both papers were based on comparisons of patterns in the genomes of many living individuals from different genetic groups and geographic regions, and of ancient skeletons.

David Reich of Harvard, the senior author of a paper published Tuesday in the journal Nature, said the DNA pattern was “surprising and unexpected, and we weren’t really looking for it.” [….]

[….] David Meltzer, an anthropologist and archaeologist at Southern Methodist University and another author of the Science paper, said the difference in interpretation between the two groups was “not an irresolvable problem.” More analysis of ancient DNA or the discovery of a new skeleton could provide an answer.

Read the full article, “Scientists Trace an Ancient DNA Link Between Amazonians and Australasians.”

Follow SMUResearch.com on twitter at @smuresearch.

SMU is a nationally ranked private university in Dallas founded 100 years ago. Today, SMU enrolls nearly 11,000 students who benefit from the academic opportunities and international reach of seven degree-granting schools. For more information see www.smu.edu.

SMU has an uplink facility located on campus for live TV, radio, or online interviews. To speak with an SMU expert or book an SMU guest in the studio, call SMU News & Communications at 214-768-7650.

Tags David Meltzer, Dedman College, SMU Department of Anthropology

Culture, Society & Family Fossils & Ruins Researcher news SMU In The News

Los Angeles Times: Native American origins: When the DNA points two ways

Post author By Margaret Allen
Post date July 22, 2015

Scientists are analyzing ancient and modern DNA to learn more about how people first colonized the Americas. Pictured here: tools discovered in 1968 at a Clovis-era burial site in western Montana, alongside remains of a boy who died more than 12,000 years ago, known as Anzick-1. The child's DNA was used as a basis for comparison in two new genetics studies released on Tuesday. (Sarah L. Anzick / AP) — Scientists are analyzing ancient and modern DNA to learn more about how people first colonized the Americas. Pictured here: tools discovered in 1968 at a Clovis-era burial site in western Montana, alongside remains of a boy who died more than 12,000 years ago, known as Anzick-1. The child’s DNA was used as a basis for comparison in two new genetics studies released on Tuesday. (Sarah L. Anzick / AP)

Los Angeles Times reporter Eryn Brown interviewed SMU’s David Meltzer, a professor in the SMU Department of Anthropology in the Dedman College of Humanities and Sciences, about a new large genome-scale study that revealed that the ancestors of all present-day Native Americans arrived in the Americas as part of a single migration wave, no earlier than 23,000 years ago.

The finding addresses the ongoing debate over when and how many times the ancestors of present-day Native Americans entered the New World from Siberia.

Meltzer is a member of the National Academy of Sciences and is Henderson-Morrison Professor of Prehistory in SMU’s Dedman College.

The Los Angeles Times article published July 21, 2015.

Read the full article, “Native American origins: When the DNA points two ways.”

EXCERPT:

By Eryn Brown
Los Angeles Times

This week, two teams of scientists released reports detailing the origins of Native American peoples. Both groups looked at ancient and modern DNA to attempt to learn more about the movements of populations from Asia into the New World, and about how groups mixed once they got here. Both discovered a hint that some Native Americans in South America share ancestry with native peoples in Australia and Melanesia.

But the two groups came to different conclusions when it came to how that DNA with ties to Oceania made its way into the Native American genome.

In a wide-ranging paper in the journal Science, University of Copenhagen Centre for GeoGenetics Director Eske Willerslev and coauthors studied genomes from ancient and modern people in the Americas and Asia. They concluded that migrations into the New World had to have occurred in a single wave from Siberia, timed no earlier than 23,000 years ago. They also calculated that any genes shared with Australo-Melanesian peoples must have been contributed through relatively recent population mixing.

In the meantime, Harvard Medical School geneticist David Reich and colleagues, focusing more closely on the Australo-Melanesian genes in a study published in Nature, came to a different conclusion: that the DNA had to have arrived in the Americas very long ago and that founding migrations occurred in more than one wave.

“It was crazy and unexpected and very weird and we spent the last year and a half trying to understand it,” Reich said on Monday. But “it’s inconsistent to a single founding population. People in Amazonia have ancestry from two divergent sources…we think this is a real observation.”

David Meltzer, an archaeologist at Southern Methodist University in Dallas and a coauthor of the Science paper, said that researchers in his field had been wrestling with the early history of the Americas for centuries — debating when the first settlers arrived here, whether there were pulses of migrations, and so on.

Read the full article, “Native American origins: When the DNA points two ways.”

Follow SMUResearch.com on twitter at @smuresearch.

Tags David Meltzer, Dedman College, SMU Department of Anthropology

Culture, Society & Family Earth & Climate Fossils & Ruins Researcher news

Large genome-scale study finds Native American ancestors arrived in single migration wave

Post author By Margaret Allen
Post date July 21, 2015

No support for ‘Paleoamerican Model,’ which holds that Central and South American groups were relicts of an early and separate migration into the Americas

This area around the confluence of the Silverthrone and Klinaklini Glaciers in southwestern British Columbia provides a glimpse into how the terrain traveled by Native Americans in Pleistocene times may have appeared. (Credit: David J. Meltzer).

A new large genome-scale study reveals that the ancestors of all present-day Native Americans arrived in the Americas as part of a single migration wave, no earlier than 23,000 years ago.

The finding addresses the ongoing debate over when and how many times the ancestors of present-day Native Americans entered the New World from Siberia.

There is archaeological evidence of modern humans in the Americas by about 15,000 years ago.

The new study was conducted by an international team headed by the Centre for GeoGenetics at the University of Copenhagen.

“With this study,” said study co-author David J. Meltzer, in the Department of Anthropology, Southern Methodist University, “we are not only addressing key questions related to the peopling of the Americas, we are beginning to integrate the archaeological, anatomical and genetic evidence bearing on that process.”

The study, “Genomic evidence for the Pleistocene and recent population history of Native Americans,” published online July 21, 2015, ahead of print in the leading scientific journal Science.

Within the Americas, the ancestral Native American pool diversified into two basal branches around 13 thousand years ago. The team also reports a later gene flow into some Native Americans from groups related to present-day East Asians and Australo-Melanesians.

Finally, the results from this study show no support for certain historical Central and South American groups with distinctive cranial morphology being relicts of an early and separate migration into the Americas, as proposed by the ‘Paleoamerican Model’.

Debate centers around demographic processes that led to peopling of Americas
Although there is little disagreement in the scientific literature that the ancestors of present-day Native Americans originated in Siberia, debate over the demographic processes that led to the peopling of the Americas still persists.

Experts know through archaeological sites such as Monte Verde in Chile that humans were present in the Americas by about 15,000 years ago.

The question remains, however, as to when the first Native Americans cross over from Siberia into the New World?

Did they arrive in a single wave or did successive migration waves give rise to the genetic diversity prevalent among present-day Native Americans? Did they split from their Old World ancestors and immediately cross into the Americas? Or was there, as one genetic model suggests, an “incubation” period in Beringia, the now-inundated land bridge that connected northeastern Siberia to Alaska? And if they came in a single wave, when did the ancestral Native American population split into the genetic branches seen today among their descendants?

Tracing the initial migrations into the Americas
To develop details of when and how the Americas were peopled, the team generated genomic data from several present-day Native American and Siberian populations, which are poorly represented in the genetic literature.

The researchers also sequenced ancient samples from across the Americas, spanning about 6,000 to 200 years ago to trace the genetic structure over time.

“Our study presents the most comprehensive picture of the genetic prehistory of the Americas to date,” said one lead author Maanasa Raghavan, a postdoctoral researcher at the Centre for GeoGenetics. “We show that all Native Americans, including the major sub-groups of Amerindians and Athabascans, descend from the same migration wave into the Americas. This was distinct from later waves that gave rise to the Paleo-Eskimo and Inuit populations in the New World Arctic region.”

This initial migration of the ancestors of all present-day Native Americans happened no earlier than 23,000 years ago, the new study found.

That represents the split date of Native Americans from East Asian and Siberian populations and is very similar for both Amerindians and Athabascans, which confirms that both groups arrived into the New World as part of the same migration.

“We applied several statistical methods that differ in modelling or utilize different information in the data,” said Yun Song, a study co-author and a professor at the University of California at Berkeley. “That we obtained consistent results across different methods is significant and reassuring.”

It is likely that after diverging from Old World populations around 23,000 years ago, the ancestral Native Americans remained isolated in Beringia for about 8 thousand years ago, given that the earliest archaeological evidence for humans in the Americas is around 15 thousand years ago.

A timeline of the genomic landscape of the Americas
Since Amerindians and Athabascans were part of the same migration into the Americas, the current genetic differences observed between them would have emerged sometime after 23,000 years ago.

The team found evidence for a split in the ancestral Native American gene pool that lead to the formation of two distinct genetic branches, namely the northern and southern branches, and that this split occurred about 13,000 years ago.

The northern branch was found to be present in northern North America and included both northern Amerindian groups as well as Athabascans. The southern branch, in contrast, included Amerindians from southern North America and Central and South America.

“We can date this split so precisely in part because we previously have analyzed the 12,600 years ago remains of a boy associated with the first unique Native American culture – the Clovis culture,”said study co-author Rasmus Nielsen from the Department of Integrative Biology at the University of California at Berkeley. “The first diversification of the ancestors of modern Native Americans happened in the Americas and likely just before — or at the time of — the appearance of the Clovis culture.”

When comparing the genetic affiliations of sequenced ancient samples from the Americas, the team found that several samples were genetically more closely related to modern-day populations from the same geographical location. This result indicates that there was a genetic and geographic continuity of Native American groups across the millennia in at least some parts of the Americas.

A recent Old World connection
The study reports a signal of gene flow between some Native Americans and groups related to present-day East Asians and Australo-Melanesians, the latter including Papuans, Solomon Islanders and South East Asian hunter-gatherer groups.

While the signal is weak, it presents an intriguing scenario of a distant Old World connection to Native Americans after their split from one another and after the latter had peopled the Americas.

“It’s a surprising finding and it implies that New World population were not completely isolated from the Old World after their initial migration,” said study leader Eske Willerslev, Lundbeck Foundation Professor from the Centre for GeoGenetics at the Natural History Museum, University of Copenhagen. “We cannot say exactly how and when this gene flow happened, but one possibility is that it came through the Aleutian Islanders living off the coast of Alaska.”

A genetic relationship with the Australo-Melanesians, however weak, invokes a highly debated hypothesis in the scientific literature that suggests, based on cranial morphology, that populations related to Australo-Melanesians were part of a separate migration. From them, that gave rise to the earliest Americans (Paleoamericans), who were later replaced by the ancestors of present-day Native Americans.

Genomic analyses indicates Palaeoamericans related to preseng-day Native Americans
The current study undertook genomic analyses on historical Central and South American populations considered to be relicts of Paleoamericans, namely the Pericúes and Fuego-Patagonians. It found no evidence, however, for them being closely related to Australo-Melanesians.

On the contrary, the results show that they were genetically closest to present-day Native Americans, a finding supported by re-analysis of cranial morphological evidence.

“Our findings show that supposed Palaeoamerican relict populations, such as the Pericúes and Fuego-Patagonians, belong to the same population as present-day Native Americans and that the distinct cranial morphology of these groups is not a consequence of a distinct migration history,” said one of the lead authors, Cristina Valdiosera, a postdoctoral researcher at the Centre for GeoGenetics.

The lines of evidence do not, as yet, fully converge, said SMU’s Meltzer, an expert on the prehistoric Native American Clovis culture.

“For example, was there a causal link between the Clovis expansion known archaeologically and the genetic divergence of the northern and southern branches?” he said. “If so, how does the evidence of a pre-Clovis presence at sites such as Monte Verde fit in? As more archaeological sites and remains are dated and ancient and modern genomes are sequenced, we will be able to resolve these issues, and develop a more precise record of the colonization of what was then a truly New World.”

Willerslev said the study also seems to have challenged older hypotheses such as a Beringian incubation for Native American ancestors for tens of thousands of years; entrance to the Americas much earlier than the Last Glacial Maximum; and, independent migrations of Amerindians and Athabascan ancestors into the Americas.

“At the same time, we see surprises including genetic signals of East Asians and Australo-Melanesians, presumably coming in after the first migration wave,” he said. — University of Copenhagen, SMU

Follow SMUResearch.com on twitter at @smuresearch.

Tags David Meltzer, Dedman College, SMU Department of Anthropology

Using ancient DNA, researchers have created a unique picture of how a prehistoric migration route evolved over thousands of years – revealing that it could not have been used by the first people to enter the Americas, as traditionally thought.

SMU scientists and their research have a global reach that is frequently noted, beyond peer publications and media mentions.

Book a live interview

Related links

More SMU Research news

Book a live interview

Related links

More SMU Research news

No support for ‘Paleoamerican Model,’ which holds that Central and South American groups were relicts of an early and separate migration into the Americas

Book a live interview

Related links

More SMU Research news