Founded in 1902 by steel magnate and philanthropist Andrew Carnegie, The Carnegie Institution was envisioned a place where the exceptional individual might find opportunity for a lifetime of discovery. Today, such individuals work within a five-department structure that encompasses basic research in astronomy, biology, and the earth sciences. Scientists at one of those departments, the Geophysical Laboratory, study questions about the Earth's chemistry and evolution. The following essay explores how a handful of the scientists there the biogeochemists are also applying their tools to questions of human prehistory.