There have been numerous attempts to decipher the rongorongo script of Easter Island since its discovery in the late nineteenth century. As with most undeciphered scripts, many of the proposals have been fanciful. Apart from a portion of one tablet which has been shown to deal with a lunar calendar, none of the texts are understood, and even the calendar cannot actually be read. The evidence is weak that rongorongo directly represents the Rapa Nui language – that is, that it is a true writing system – and oral accounts report that experts in one category of tablet were unable to read other tablets, suggesting either that rongorongo is not a unified system, or that it is proto-writing that requires the reader to already know the text. Assuming that rongorongo is writing, there are three serious obstacles to decipherment: the small number of remaining texts, comprising only 15,000 legible glyphs; the lack of context in which to interpret the texts, such as illustrations or parallel texts which can be read; and the fact that the modern Rapa Nui language is heavily mixed with Tahitian and is unlikely to closely reflect the language of the tablets—especially if they record a specialized register such as incantations—while the few remaining examples of the old language are heavily restricted in genre and may not correspond well to the tablets either.
Since a proposal by Butinov and Knorozov in the 1950s, the majority of philologists, linguists and cultural historians have taken the line that rongorongo was not true writing but proto-writing, that is, an ideographic- and rebus-based mnemonic device, such as the Dongba script of the Nakhi people, which would in all likelihood make it impossible to decipher. This skepticism is justified not only by the failure of the numerous attempts at decipherment, but by the extreme rarity of independent writing systems around the world. Of those who have attempted to decipher rongorongo as a true writing system, the vast majority have assumed it was logographic, a few that it was syllabic or mixed. Statistically, it appears to have been compatible with neither a pure logography nor a pure syllabary. The topic of the texts is unknown; various investigators have speculated they cover genealogy, navigation, astronomy, or agriculture. Oral history suggests that only a small elite were ever literate, and that the tablets were considered sacred.
Accounts from Easter Island
In the late 19th century, within a few years to decades of the destruction of Easter Island society by slave raiding and introduced epidemics, two amateur investigators recorded readings and recitations of rongorongo tablets by Easter Islanders. Both accounts were compromised at best, and are often taken to be worthless, but they are the only accounts from people who may have been familiar with the script first-hand.
Jaussen In 1868 the Bishop of Tahiti, Florentin-Étienne Jaussen, received a gift from recent converts on Easter Island: a long cord of human hair wound around a discarded rongorongo tablet. He immediately recognized the importance of the tablet, and asked Father Hippolyte Roussel on Easter Island to collect more tablets and to find islanders capable of reading them. Roussel was able to acquire only a few additional tablets, and he could find no-one to read them, but the next year in Tahiti Jaussen found a laborer from Easter Island, Metoro Tauꞌa Ure, who was said to know the inscriptions "by heart".
Sometime between 1869 and 1874, Jaussen worked with Metoro to decipher four of the tablets in his possession: A Tahua, B Aruku kurenga, C Mamari, and E Keiti.Fischer believes he can date these sessions to August 1873 A list of the glyphs they identified was published posthumously, along with a complete account of the chants for A and B. This is the famous Jaussen list. Though at first taken for a Rosetta Stone of rongorongo, it has not led to an understanding of the script. It has been criticized for, among other inadequacies, glossing five glyphs as "porcelain", a material not found on Easter Island. However, this is a mistranslation: Jaussen glossed the five glyphs as porcelaine, French for both "cowrie" and the cowrie-like Chinese ceramic which is called porcelain in English. Jaussen's Rapanui gloss, pure, means specifically "cowrie".
Almost a century later, Thomas Barthel published some of Jaussen's notes. He compared Metoro's chants with parallel passages in other tablets and discovered that Metoro had read the lines of Keiti forwards on the reverse but backwards on the obverse. Jacques Guy found that Metoro had also read the lunar calendar in Mamari backwards, and failed to recognize the "very obvious" pictogram of the full moon within it, demonstrating a lack of any understanding of the contents of the tablets.
Thomson William J. Thomson, paymaster on the USS Mohican, spent twelve days on Easter Island from 19 December to 30 December 1886, during which time he made an impressive number of observations, including some which are of interest for the decipherment of the rongorongo.
Ancient calendar
Among the ethnographic data Thomson collected were the names of the nights of the lunar month and of the months of the year. This is key to interpreting the single identifiable sequence of rongorongo, and is notable in that it contains thirteen months; other sources mention only twelve. Métraux criticizes Thomson for translating Anakena as August when in 1869 Roussel identified it as July, and Barthel restricts his work to Métraux and Englert, because they are in agreement while "Thomson's list is off by one month". However, Guy calculated the dates of the new moon for years 1885 to 1887 and showed that Thomson's list fit the phases of the moon for 1886. He concluded that the ancient Rapanui used a lunisolar calendar with kotuti as its embolismic month (its "leap month"), and that Thomson chanced to land on Easter Island in a year with a leap month.
Ure Vaꞌe Iko's recitations Thomson was told of an old man called Ure Vaꞌe Iko who "professes to have been under instructions in the art of hieroglyphic reading at the time of the Peruvian raids, and claims to understand most of the characters". He had been the steward of King Ngaꞌara, the last king said to have had knowledge of writing, and although he was not able to write himself, he knew many of the rongorongo chants and was able to read at least one memorized text. When Thomson plied him with gifts and money to read the two tablets he had purchased, Ure "declined most positively to ruin his chances for salvation by doing what his Christian instructors had forbidden" and finally fled. However, Thomson had taken photographs of Jaussen's tablets when the USS Mohican was in Tahiti, and he eventually cajoled Ure into reading from those photographs. The English-Tahitian landowner Alexander Salmon took down Ure's dictation, which he later translated into English, for the following tablets:
{| class="wikitable" |+ Ure Vaꞌe Iko's readings ! Recitation ! Corresponding tablet |- | Apai | E (Keiti) |- | Atua Matariri | R (Small Washington) ? |- | Eaha to ran ariiki Kete | S (Great Washington) ? |- | Ka ihi uiga | D (Échancrée) |- | Ate-a-renga-hokau iti poheraa | C (Mamari)
Salmon's Rapanui was not fluent, and apart from Atua Matariri, which is almost entirely composed of proper names, his English translations do not match what he transcribed of Ure's readings. The readings themselves, seemingly reliable although difficult to interpret at first, become clearly ridiculous towards the end. The last recitation, for instance, which has been accepted as a love song on the strength of Salmon's English translation, is interspersed with Tahitian phrases, including words of European origin, such as "the French flag" (te riva forani) and "give money for revealing [this]" (horoa moni e fahiti), which would not be expected on a pre-contact text. The very title is a mixture of Rapanui and Tahitian: poheraꞌa is Tahitian for "death"; the Rapanui word is matenga. Ure was an unwilling informant: even with duress, Thomson was only able to gain his cooperation with "the cup that cheers" (that is, rum):
Nonetheless, while no one has succeeded in correlating Ure's readings with the rongorongo texts, they may yet have value for decipherment. The first two recitations, Apai and Atua Matariri, are not corrupted with Tahitian. The verses of Atua Matariri are of the form X ki ꞌai ki roto Y, ka pû te Z "X by copulating with Y produced Z": "Moon (?) by copulating with Darkness (?) produced Sun" (verse 25), "Killing by copulating with Flat-one-of-the-white-tail (the sting ray) produced the shark" (verse 28), "Stinging-fly by copulating with Swarm-of-flies produced the fly" (verse 16). These verses have generally been interpreted as creation chants, with various beings begetting additional beings, as is typical of Polynesian cosmogonies. Some verses of Atua Matariri reference myths from other parts of Polynesia, while others refer to Easter Island's own mythology. For example: "Tiki-the-lord by copulating with Running-and-flowing-down [water] produced the rockfish" (verse 30), "Tiki-the-lord by copulating with Hina-the-heaped-up produced Hina-kauhara" (verse 31), "Tiki-the-lord by copulating with Stone produced burning-red-meat (?)" (verse 32).
These verses summarize a myth about Makemake (the Easter Island equivalent to Polynesian Tāne and Tiki) where the god attempts to create mankind by copulating with various objects, including a water-filled gourd, stones and a heap of soil. A close parallel was recorded in a Mangarevan chant that lists twenty procreations of Tiki:
"Tiki procreated with the candlenut to produce offspring, hence the milky sap, oh".
Guy offered an alternative interpretation by noting that the phrasing is similar to the way compound Chinese characters are described. For example, the composition of the Chinese character 銅 tóng "copper" may be described as "add 同 tóng to 金 jīn to make 銅 tóng" (meaning "add Together to Metal to make Copper"), which is nonsense when taken literally. He hypothesizes that the Atua Matariri chant which Ure had heard in his youth, although unconnected to the particular tablet for which he recited it, was a genuine rongorongo chant: A mnemonic which taught students how the glyphs were composed.
Fanciful decipherments Since the late nineteenth century, there has been all manner of speculation about rongorongo. Most remained obscure, but a few attracted considerable attention.
In 1892 the Australian pediatrician Alan Carroll published a fanciful translation, based on the idea that the texts were written by an extinct "Long-Ear" population of Easter Island in a diverse mixture of Quechua and other languages of Peru and Mesoamerica. Perhaps due to the cost of casting special type for rongorongo, no method, analysis, or sound values of the individual glyphs were ever published. Carroll continued to publish short communications in Science of Man, the journal of the (Royal) Anthropological Society of Australasia until 1908. Carroll had himself founded the society, which is "nowadays seen as forming part of the 'lunatic fringe'."