Between 2007 and 2009, geneticist Erik Thorsby and colleagues published two studies in "Tissue Antigens" that evidence an Amerindian genetic contribution to human populations on Easter Island, determining that it was probably introduced before European discovery of the island. In 2014, geneticist Anna-Sapfo Malaspinas of The Center for GeoGenetics at the University of Copenhagen published a study in "Current Biology" that found human genetic evidence of contact between the populations of Easter Island and South America, dating to approximately 600 years ago (i.e. 1400 CE ± 100 years).