There was a long-held idea that rongorongo was an extreme outlier of Indus Script, itself undeciphered, but a distant ancestor to the Dravidian languages. That

There was a long-held idea that rongorongo was an extreme outlier of Indus Script, itself undeciphered, but a distant ancestor to the Dravidian languages. That notion has been pretty thoroughly trashed, and it's honestly pretty surprising that it's got any life in it because if you even just casually look at the source materials, the likenesses are extremely few and far between. Steve Fisher - the "decoder" of the Phaistos Disc - also claimed to decode the script, but, eh, well. Maybe? Fisher's whole schtick is to break things into metaphorical levels that make the notion of "coding" sort of nonsensical. He's a neat guy, and maybe I'm just too much of a computationalist to see this form of decoding as anything more rigorous than, say, folklore. And a lot of the patterns Fisher said he found don't hold up. For my two cents, I think these are related to polynesian petroglyphs (see also the Waianae petroglyphs on Oahu) but employed in a new manner, one that the rapanui were exposed to either with mesoamerican admixture or with the arrival of the Spanish. So they took these glyphs with ritual meaning, but they saw this new way of employing glyphs adjacent in space to derive new meanings, and then they combined their glyphs with this new "writing" method. Doesn't much help with deciphering, I guess, but it does explain where the symbology might come from. Also, the notion of a Polynesian syllabary is just ridiculously fascinating. Every civilization has, like, one thing they're just amazing at, and the Polynesians knew how to boat.