This electron microscope image provided by researchers shows a section of a Pithovirus particle, dark outline, inside an infected Acanthamoeba castellanii cell. Julia Bartoli, Chantal Abergel/AP hide caption

itoggle caption Julia Bartoli, Chantal Abergel/AP

Plant pathologists sequenced the genome of 19th century potato specimens like this one from London's Kew Gardens herbarium, collected during the height of the Irish famine in 1847. Marco Thines/Senckenberg Gesellschaft für Naturforschung hide caption

itoggle caption Marco Thines/Senckenberg Gesellschaft für Naturforschung