While most Harvard students take their classes indoors two or three times a week, the members of Anthropology 1140, “Human Modification of the Landscape,” have met exactly once—for 10 straight days in the Harvard Forest—and spent their time poking holes in the validity of a scientific method that to date has been considered watertight.
As they indulged in cookies, cheese, and sparkling cider yesterday afternoon, participants in the 10-member seminar unveiled their final projects, which examine the effects of humans on the Harvard Forest.
The brand-new class is taught by Clay Professor of Scientific Archaeology Noreen Tuross. The students spent their sojourn in the forest integrating field and lab work to investigate the accuracy of using phosphates to measure the intensity of land usage.
Traditionally, archaeologists have interpreted high levels of phosphates as evidence of humans.
“They accept it as truth,” Tuross said, “but that assumption has never been tested empirically.”
The class focused its research on Pierce Farm, a small area of the 3,000-acre forest.
Using the forest “is like dropping into science heaven,” Tuross said.
Harvard possesses extensive records detailing how the land had been used in the past, including land deeds and soil profiles.
This enabled the class to compare phosphate samples to what is actually known about the land.
“We took these maps as truth and then said, ‘what do the phosphates tell us?’” explained Tuross.
In the 1800s, Massachusetts was 80 percent deforested, as a result of farming.
Although that number today more closely resembles 20 percent, study of vegetation patterns and phosphate levels can help scientists map out exactly what the forest looked like 150 years ago.
The class divided the former farmland into five sections: cultivated land, improved pasture, unimproved pasture, woodlot and farmhouse.
Students found that only the woodlot and the location of the farmhouse exhibited phosphate levels that were significantly different than in the other areas. These findings indicate that the method of testing phosphate levels only “sort of” works, said Tuross.
“It really seems like in previous applications, the phosphates have been over-interpreted,” said Cheryl Makarewicz, who is in her fifth year at the Graduate School of Arts and Sciences and is one of two teaching fellows for the tiny seminar.