Public Health Students Test “The Grandma Hypothesis”

When it comes to bath time, grandmothers in many families instruct their grandkids to “scrub behind the ears, the belly button” and other hard to reach places. The hypothesis is that those “hotspots” are often not washed carefully and thus harbor more fuzz, grime and an unhealthy collection of microbes. But would the grandma hypothesis hold up if put to the test?

Two professors, Marcos Pérez-Losada and Keith Crandall, at the George Washington University Milken Institute School of Public Health developed an innovative project-based learning activity as part of their genomics course so that students could test this hypothesis. Pérez-Losada provided the background material on genomics and then led the students through the process of collecting their own data, starting with swabbing certain hotspots – behind the ears, between their toes and in the navel as well as control areas – as part of the lab experience. The graduate students then extracted and sequenced DNA learning new techniques all along the way to quantify the microbes in those hotspots and control regions for comparisons.

Students then moved from the ‘wet-lab’ to the ‘computational-lab’ and learned how to analyze the data from their own experiments and look for microbes living on the skin. The students found that body sites cleaned more frequently such as the forearm had a more diverse, and thus healthier, collection of microbes compared to sites like the bellybutton. In addition, the students found significant differences in the proportions of microbes found in the hotspots compared to the more frequently washed body sites.

The hands-on research project helped the students learn the complex course material more thoroughly, Pérez-Losada said. Students’ grades from the 2019 class on multiple assessments for the targeted topics significantly improved with the project-based learning approach compared to the 2018 class, a more traditional approach that did not include these activities. Students were also polled at the end of the class and asked if they still had questions about key concept in genomics. The survey revealed that significantly fewer students in the 2019 class still had questions about key concepts in genomics.

“This study demonstrates the power of combining research and education in the classroom. Our students had demonstrably better academic outcomes as a result of this innovative project-based learning approach allowing them hands-on experience in genomics,” said Crandall, a professor of Biostatistics and Bioinformatics and Director of the Computational Biology Institute. “As a bonus, they showed that my grandma was right, those hotspots need additional effort with respect to washing to keep a healthy microbial diversity intact.”

Pérez-Losada and Crandall summarized the student experiment along with data indicating the hands-on course helped students master the material in a paper published March 6 in the Journal of Microbiology & Biology Education.

The study was funded by an award to Pérez-Losada from the Milken Institute School of Public Health Master Teacher Academy.