Faculty

The 2013 Stretch Student Saga: A Change in Course

Joseph Blumberg

Professor Carl Renshaw and 11 students just completed an unanticipated venture into the flood-ravaged canyons of Boulder, Colo. This was a detour in their 10-week off-campus odyssey known as “the Stretch.” Their original destination—the national parks—had been rendered inaccessible by the Federal government shutdown.

In a period of eight days, from September 9 through 16, Boulder experienced more than 17 inches of rain, amounting to what the National Weather Service called a 1,000-year rain, causing a 100-year flood. Houses were toppled and cars were carried away by the raging torrents rushing through the Colorado canyons.

A Trace of Arsenic (Discover)

In a story about arsenic and whether any level of the naturally occurring element might be safe to ingest, Discover magazine speaks with a number of Dartmouth scientists who’ve done research on arsenic in drinking water and in food products.

The scientists include Research Associate Professor of Earth Sciences Brian Jackson, who led a study that found trace levels of the carcinogen in baby food that had been sweetened with organic brown rice syrup, and Margaret Karagas, an epidemiologist and professor of community and family medicine at the Geisel School of Medicine and the senior author of a study that discovered that babies whose mothers drank well water from the arsenic-rich bedrock of New Hampshire tended to have low birth weights and be more than usually susceptible to childhood infections.

Evidence Found for Planet-Cooling Asteroid (Nature)

Nature points to a new study co-authored by Dartmouth’s Mukul Sharma, a professor in the Department of Earth Sciences, that links the impact of a comet or meteor striking the Earth to the dramatic global climate change that occurred 12,900 years ago.

“I’d say there’s evidence of an impact happening, for sure,” Sharma tells Nature. The researchers recovered minerals in Pennsylvania similar to those found in Quebec, where Sharma and his colleagues believe the impact took place, Nature reports.

Read the full story, published 9/2/13 by Nature.

Study Links Prehistoric Climate Shift, Cosmic Impact

For the first time, a dramatic climate shift that has long fascinated scientists has been linked to the impact in Quebec of an asteroid or comet, Dartmouth researchers and their colleagues report in a new study funded by the National Science Foundation.

The event took place about 12,900 years ago, at the beginning of the Younger Dryas period, and marks an abrupt global change to a colder, dryer climate, with far-reaching effects on both animals and humans, the scientists say. In North America the big animals, including mastodons, camels, giant ground sloths, and saber-toothed cats, all vanished. Their human hunters, known to archaeologists as the Clovis people, set aside their heavy-duty spears and turned to a hunter-gatherer subsistence diet of roots, berries, and smaller game.

Dartmouth Drills at Denali to Document Climate Change

JOSEPH BLUMBERG

On June 18, Erich Osterberg left Alaska’s Denali National Park, where a collaborative Dartmouth-University of Maine-University of New Hampshire team had chronicled 1,000 years of regional climatic history.

“We drilled two 700-foot, 4-inch-wide holes to bedrock through the glacier on Mount Hunter, the third highest peak in the Alaska Range and Denali’s closest neighbor,” says Osterberg, an assistant professor in Dartmouth’s Department of Earth Sciences.  An unusual lack of storms allowed the team to complete the ice core drilling and an array of supporting field research quickly and efficiently. “Alaska’s exceptionally warm summer this year also drew attention to the shifting climate picture,” he adds.

Phylogeny: Rewriting Evolution (Nature)

Scientific progress has transformed Darwin’s simple evolutionary tree of life into a bush with a myriad of branches, representing phylogenetic relationships. Now the research of Dartmouth’s molecular palaeobiologist Kevin Peterson is telling us that the branches may all be in the wrong places. Peterson, an associate professor of biological sciences and an adjunct professor of earth sciences, is the subject of an extensive feature story published in the journal Nature.

The article discusses how Peterson’s work on micro RNAs (miRNAs)—short regulatory molecules found in cells—has upended some long-held notions about the evolutionary history of mammals and their relationships today. When miRNAs appears in an animal’s ancestral lineage, they are rarely lost but accumulate over time. This makes miRNAs an important tool in discerning relationships and solving evolutionary puzzles.

Dartmouth Researchers Say a Comet Killed the Dinosaurs

JOSEPH BLUMBERG

In a geological moment about 66 million years ago, something killed off almost all the dinosaurs and some 70 percent of all other species living on Earth. Only those dinosaurs related to birds appear to have survived. Most scientists agree that the culprit in this extinction was extraterrestrial, and the prevailing opinion has been that the party crasher was an asteroid.

Not so, say two Dartmouth researchers. Professors Jason Moore and Mukul Sharma of the Department of Earth Sciences favor another explanation, asserting that a high-velocity comet led to the demise of the dinosaurs.
Recently, asteroids have been in the headlines. On February 15, 2013, an asteroid exploded in the skies over Siberia. Later that day, another swept past the Earth in what some regard as a close call—just 17,000 miles away.

Dartmouth Scientists Study Irene’s Impact to Predict Future Flooding Hazards

Joseph Blumberg

The devastation recently wrought by Superstorm Sandy reawakens memories of Tropical Storm Irene, still fresh in the minds of many Vermonters. Irene’s legacy is evident in ruined rivers, shattered homes, and historic covered bridges washed away. Perhaps more unsettling is the prospect of more to come, say a pair of Dartmouth professors who are studying the damage Irene left behind.

“There is no smoking gun here that directly associates Irene with global warming, but all the climate models suggest that storms like Irene and Sandy are going to increase in intensity, magnitude, and frequency,” says Frank Magilligan, a professor in the Department of Geography at Dartmouth.

Can a Jellyfish Unlock the Secret of Immortality? (The New York Times)

In a New York Times story about research on a hydrozoan known as the “immortal jellyfish,” Dartmouth’s Kevin Peterson, associate professor of biological sciences and adjunct professor of earth sciences, says there is a “shocking amount of genetic similarity between jellyfish and human beings.” The genetic similarities, Peterson tells the Times, may have implications for medicine, especially in terms of longevity and cancer research.

“Immortality might be much more common than we think,” Peterson tells the Times. “There are sponges out there that we know have been there for decades. Sea-urchin larvae are able to regenerate and continuously give rise to new adults.” He adds, “This might be a general feature of these animals. They never really die.”

Read the full story, published 11/28/12 in The New York Times.

Yes Martha, It Was an Earthquake!

Joseph Blumberg

Many of us felt it and more even heard the rumbling. At approximately 7:12 p.m. last evening (Tuesday, October 16), the ground shook throughout New England.

According to the United States Geological Survey (USGS), the epicenter of the 4.6 magnitude quake was in southwest Maine, three miles west of Hollis Center, originating at a depth of about five kilometers. The USGS initially gave the earthquake a 4.6-magnitude rating and later downgraded it to 4.0.

Leslie Sonder felt it on campus. An associate professor in Dartmouth’s Department of Earth Sciences, she first ascribed it to someone walking down the hall. “Fairchild does shake a bit when people walk, but this really was an earthquake,” she says.