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Lessons From the Field
by Judith Saks
Rewards large and small come from getting out into the world and digging in the dirt.
The chance to learn firsthand about human evolution by joining their teacher, noted chemist Anne Skinner, on an archeological dig in India gave two adventurous Williams College students more than aching muscles. As they labored in the hot sun, they gained new skills and an appreciation of chemistry's contribution to explorations of the past.
Sergio Marte, age 20, and Daniel Jamorabo, age 21—both New Yorkers and community service-minded chemistry majors who plan to become doctors—spent two weeks in January with Skinner and an Indian team exploring several sites along the Narmada River Valley, 100 miles from Bhopal. An HHMI undergraduate education program grant supported their hands-on learning experience about human evolution via chemistry.
"It was a great opportunity to see that chemistry is not just about mixing chemicals and making explosions," says Marte. "It was a lot about going out into the field, collecting data, and working with people ... who can provide perspectives and insight into the work you are doing." Marte talked to local villagers who knew that companies had been excavating in the region—crucial information needed to evaluate whether artifacts were indigenous to the site or had been washed down from upriver.
Skinner earned a "very conventional physical chemistry Ph.D." but now regards increasing the understanding of human evolution as her main area of research, and she collaborates with archeologists and geologists from around the world to advance that work. Skinner is expert at dating the bones and teeth of mammal fossils with a relatively new technique, electron spin resonance (ESR), which can determine the extent of damage caused by the radioisotopes that accumulate in the animals' dead tissue and in the surrounding soil. By dating animal fossils from a geologic layer that also contains stone tools or other evidence of human activity—with the understanding that more damage occurs the longer something is buried—Skinner can approximate when human life appeared in that area.
Illustration: Elliott Golden