Graduate students across disciplines agree: as your years of graduate education increase, your knowledge and skill sets become incredibly specialized. Cue Liam Neeson in Taken, “I can tell you that I do not have money, but what I do have… [is] a very particular set of skills.” So when I asked Dr. Tara Smiley, a Research Fellow at IU’s Environmental Resilience Institute, about the most unique research she has conducted, I fully sympathized with her answer: she described sitting in a museum’s collections department, nicely dressed for an elegant birthday dinner later that evening, giving rodent specimens delicate haircuts with a pair of curved nail scissors. A very specialized skill indeed!
These hair samples were destined to be ground into fine particles (like a nice espresso) and packed into tiny aluminum tubes for stable isotopic analysis. Isotopes are alternative forms of the same element, varying in the number of neutrons per atom. For example, 1H is the most common form of hydrogen, with one neutron, while 2H is a rarer form, with two neutrons. Elements generally do not occur in one form, but rather as a mixture of different isotopes. An region’s isotope composition is influenced by various factors, from the impact of temperature and precipitation patterns on hydrogen, to the influence of local bedrock geology on strontium. Because we are what we eat, an organism like a silky mouse will take up isotope mixtures from food she eats and the water she drinks. Because stable isotopes do not decay, the isotope mixtures in her tissues become locked in a permanent signature of the biological and physical processes occurring in the place and time that her tissue – such as hair – was grown.