Every day, my distaste for Jared Diamond ages like a fine wine.
This aligns with the idea that Rapa Nui was the stepping stone via which Polynesians and Native Americans made contact, traded crops, and had kids together. I wonder if there was ever a minority NA population on the island alongside Polynesians or if it was just occasional mixed kids raised fully Polynesian.
I wonder if there was ever a minority NA population on the island alongside Polynesians
That's an interesting hypothesis and definitively worth checking, but I personally find unlikely that Rapa Nui had any sort of meaningful (in numbers) Native American minority - there's practically no material pressure to do so.
It was a similar distance from there to the nearest Polynesian island, and we know they maintained contact and trade that direction. South America would've offered entirely unique trade goods, so I don't think it's out of the question at all. These were history's greatest sailors and navigators, after all.
Certainly 10% DNA admixture requires more than just a few small interactions.
I do think that it was more than just a few small interactions, but I don't think that they happened in Rapa Nui island, or that they got the chance to develop an Amerindian minority there. I think that, instead, the Polynesians had small coastal settlements here in South America, used for trade.
So those 10% admixture would be like in your other hypothesis - mixed kids raised Polynesian.
The key is that what you said is true for the Polynesians, but not for the Amerindians - from the Polynesians' PoV the Amerindians were a big cluster of potential trading partners with exotic resources, but from the Amerindians' PoV it was just a small island in the middle of nowhere, that could be only safely reached by knowing how to navigate the oceans - and at least Andean Amerindians likely didn't know how to do it, as they were way more focused on land-based tech (terrace farming, road building, freeze-drying...).
That makes a lot of sense! Agreed that that's more likely. Though those settlements would've been pretty transient and/or small since we have nothing in the archaeological record. And no pigs.
It's tempting to look for potential vocab exchange between Rapa Nui and (Quechua and Aymara). That could help dating the exchange with the Andes, as the lexicon stops following the lender's sound changes to follow the borrower's instead.
(Polynesian syllabic structure and small phonemic stock make this extra tricky though. For example, Classical Quechua /s ʂ h/ would probably end all merged into /h/, and you'd see multiple epenthetic vowels popping up.)
Even then I wouldn't be surprised if they contacted the folks up south, like the Mapuche. Specially as I don't expect the landing spot from a Rapa Nui → South America to be the best spot to start the opposite travel, due to sea currents.
It seems likely that the Polynesian word(s) for sweet potato is a direct borrowing from Quecha. Beyond that I don't think there's accepted evidence for vocabulary exchange.
I gave it a check. It's hard to take a lot of conclusions from a single word, but
- Quechua - kumar, khumara
- Rapa Nui - kuma porá
- Maori - kūmara, kūmera
- Hawaiian - ʻuala
- Tongan: kumala
This got to be at least two instances of borrowing, since either Rapa Nui picked another variant of the word to borrow or solved the issue with the ending consonant in a different way (by eliding it instead of adding a new vowel).
The Hawaiian cognate underwent /k/→/ʔ/ (spelled ʻ), so it's probably really old.
Based on that, if I had to take a guess: Polynesians contacted the Amerindians multiple times across the centuries, and it was kind of a big deal for Rapa Nui ones. Sadly a better analysis would need a bigger lexicon than a single word.
