Research Insights on Infants, Trees and the Big Freeze

When College of Science and Health professors aren’t busy grading lab reports, preparing for classes, mentoring students or submitting to journals, they can often be found conducting research on a wide range of interesting topics. Get a sneak peek into a few of these projects below.

shutterstock_94330885How Do Infants Learn Social Behavior?
A baby sits on his mother’s lap, staring in fascination as a movie plays on the television before him. It may look like fun and games, but this child is actually participating in a study at the Children’s Understanding and Behavior (CUB) Lab, where Assistant Professor of Psychology Sheila Krogh-Jespersen is research director. An eye-tracker, a nifty piece of technology attached to the screen, collects critical data that helps Krogh-Jespersen determine how infants observe and engage with the world around them.

“Humans are an intensely social species, and we have to figure out very quickly in life how to navigate our complex social world,” Krogh-Jespersen explains. “Given that we are interested in how infants perceive the actions, behaviors and interactions that occur in their daily lives, the movies we show typically feature people playing with toys or having conversations.”

Krogh-Jespersen’s recent CUB Lab study investigated whether 15-month-olds could predict an individual’s future behavior based on her past actions. In the first scene of the movie, a woman reaches for one of two toys. In the second scene, the researchers change various elements, such as the location of the toys, to see how the children respond.

“We found that infants do, in fact, have this critical ability to update their knowledge and rapidly predict the woman’s future reaching actions,” says Krogh-Jespersen, adding that this type of predictive knowledge may foster social competence. “If your daughter knows that you like to play with toy cars, she might think you will be more likely to play with her if she brings you a toy car.”

shutterstock_235371946What Caused the Big Freeze?
Professor of Chemistry Wendy Wolbach went way back in time for her most recent research project. “Roughly 12,800 years ago, near the end of the Pleistocene period, a time of cold climates and drought swept the earth,” she says. “Scientists call this ‘big freeze’ the Younger Dryas, named for a flower, the Dryas octopetala.” While this flower thrived in the near glacial conditions of that time, other living creatures didn’t fare nearly as well. Woolly mammoths, saber-toothed tigers, giant sloths and dozens of other large animals met their fate, doomed to the roll call of extinction.

As a geochemist who studies the connection between large meteorite impacts and extinctions, Wolbach wanted to know whether a meteorite might have caused this abrupt cooling. Using an isolation and quantification technique she developed, Wolbach found an elevated presence of nanodiamonds, a sign of cosmic impact, in sedimentary rocks from the Younger Dryas boundary. However, Wolbach needed to ascertain whether the Younger Dryas rock layer was the same age globally to prove a causal connection between the cosmic impact event and the subsequent big freeze.

Wolbach and her colleagues used Bayesian statistical analyses of 354 radiocarbon dates taken from 30 sites, ranging from northern Syria to California and from Venezuela to Canada, to determine a 95 percent probability that the dates are indeed consistent with a single cosmic impact. “There’s been a long history of trying to figure out what caused this anomalous and enigmatic cooling,” she says. “Now that we know more, we’d like to perform similar statistical analyses on other events related to the period.”

102_asst_trees_KL - cropWhich Factors Compel Trees to Synchronize Seed Production? 
For the past five years, Assistant Professor of Ecology Jalene LaMontagne has tracked the number of cones produced by the same 1,000 white spruce trees in three regions in Wisconsin, Michigan and Minnesota. “White spruce, along with many other species of perennial plants, does what is called ‘mast seeding,’ which is defined as the synchronous and intermittent production of large seed crops by a population of plants,” LaMontagne says. “In other words, in some intermittent years, the cone (or seed) production is very high, while in most years, seed production is quite low.”

During high-yield years, each white spruce may produce thousands of seeds. But what causes the trees to synchronize their seed production? How likely is synchronization within a given spatial area? To help answer these questions, LaMontagne looks at cone production synchrony on three levels: 1) by individual tree, 2) across sites within a region and 3) between the three regions. She also collects additional information about each tree, such as trunk diameter, height and needle volume, and soon will collect soil nutrient data. Finally, LaMontagne employs data loggers to track temperatures every two hours for the entire year.

“One of the most striking findings so far is that there can be two trees that are fairly close to one another and yet they are doing different things in terms of cone production,” she says. “This suggests that it’s more than just the weather controlling the patterns of synchrony.” Since seeds form the base of the food chain, LaMontagne’s research offers biologists greater insight not only into these Midwestern boreal forests, but also into the insects, birds and mammals
who rely on seeds for survival.

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