One fragment of ancient mythology which did come through was this creation chant, which I have adapted from Métraux's reconstruction of the garbled version given by Paymaster Thomson of the U.S.S. Mohican, who obtained it from Ure vaeiko in 1866.
It proves its own antiquity: neither coconuts nor eels were known on Easter Island (which has no streams of any kind) and the word for coconut, 'niu', was used for the fruit of the miro tree. Yet the eighth line of the chant preserves a memory of both, in an allusion to the extremely ancient myth about the eel and the coconut ...
Tiki and his wife the Woman of Earth are also mentioned toward the end, and the cryptic last three lines again refer to eels, according to Métraux.
A chant of almost indentical pattern is recorded by Buck from Mangareva. Both doubtless had a common source in the Marquesas, whence the Easter Islanders evidently migrated in about the fourth century (Métraux, 99: 320-332).
God-of-angry-look by lying with Roundness made the poporo berry,
Himahima marao by lying with Lichen-in-the-soil made the lichen,
Parent-mother by lying with Pipiri hai tau made wood,
Ti by lying with Tattooing made the ti plant,
Elevation by doing it with Height made the inland grass.
Sharpness by lying with Adze produced obsidian,
Twining by lying with Beautiful-face-with-penetrating-tongue produced the morning-glory,
Parent-god by lying with Angry Eel produced the coconut,
Grove by doing it with Trunk produced the ashwood.
Veke by lying with Water-beetle made the dragonfly,
Stinging-fly by doing it with Swarm-of-flies produced the fly,
Branch by lying with Fork-of-tree made Beetle-that-lives-in-rotten-wood,
Lizard-woman by lying with Whiteness made the gannet.
Hard-soil by lying with Covering-below made the sugar cane,
Bitterness by doing it with Bad-taste produced the kape,
Tail by lying with Hina oio produced the crayfish,
Killing by doing it with Stingray made the shark.
Tiki-the-chief by lying with Heap-of-Earth made Hina kauhara;
Kuhikia by lying with Wetness made the bulrush;
Kuhikia by lying with Pigeon made the seagull;
Small-thing by doing it with Imperceptible-thing made the fine-dust-in-the-air:
It runs red, the blood of the kovare.
Abundant the kovare, rough the eels.
The rain falls in long drops."
(Legends of the South Seas)