Sam Erman (Smithsonian): Citizens of Empire: Puerto Rico, Status, and Constitutional Change. Is the filibuster unconstitutional? The Founding Fathers might not approve of today's Senate. Scott McLemee reviews Captain America and the Nationalist Superhero: Metaphors, Narratives, and Geopolitics by Jason Dittmer. The Post-Gladwellian Paradox: Stan Tsirulnikov on why intuitive is the new counterintuitive. How Timbuktu saved its books: Tristan McConnell goes behind the rescue of Mali’s historic manuscripts. The end of the Earth: For decades the very word Timbuktu seemed to convey a place that time forgot. Russian scientists say they've found “unclassified life” in Antarctic Lake. Kate Shellnutt on the problem with Christians doing the “Harlem Shake”. From Gangnam Style to the Harlem Shake, Olivia Cvitanic on why we just can’t resist a dance craze.