The rongorongo tablet from Berlin and the time-depth of Easter Island’s writing system

Rongorongo is a non-deciphered writing system from Rapa Nui (Easter Island). Because the island was isolated from the outside world until relatively recently, rongorongo has the potential of being one of only a few instances in human history of an independent invention of writing. However, no scientific consensus exists regarding the time span for when rongorongo was used. Its cessation in the 1860s is well-known but its origins are not. Here, we report on detailed analysis of one of the 23 existing rongorongo artifacts—the Berlin Tablet—including botanical wood identification, radiocarbon dating, and photogrammetric study. The wood used to create the tablet was identified as Pacific rosewood, Thespesia populnea, a species that once grew on Rapa Nui, which counters previous theories that the tablet was made from salvaged driftwood. The radiocarbon date, adjusted in accordance to the ethnographic data, suggests that the tablet was made some time between ca. AD 1830 and 1870. Prior to its collection, the tablet had spent a significant amount of time within a cave context that destroyed around 90% of its content. The text is estimated to have been over 5000 signs long, more than double the length of the next longest rongorongo text.