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Comment by swagasaurus-rex | Hacker News Reader

Several months ago a study came out showing that pacific islanders not only made it to South America 800 years ago, but sailed back to Easter Island and other pacific islands after genetic mixing.

https://www.nytimes.com/2020/07/08/science/polynesian-ancest...

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I’d assumed this was likely as the trip was done from South America in recent history: https://en.m.wikipedia.org/wiki/Kon-Tiki_expedition

I also understand there’re plants in parts of South America that originated in Polynesia.

It is the other way around. The sweet potato is natively from America, but it made it to Polynesia, unclear how.

Is it the same "Tombez Potato" writers of the 19th century report as being commonly grown and consumed in the Pacific Islands like Marquesas?

The fact that the leading theory of anthropologists for a long time was vegetation rafts is laughable in the face of the distances Polynesian people regularly traveled, it speaks to the parochial nature of much of the field.

Sweet potatoes found in Polynesia diverged from their ancestors in the Americas 100,000 years ago, long before the islands were colonized by humans.

https://www.nature.com/articles/d41586-018-04488-4

Also, the fact that many Polynesian languages used nearly the same word for "sweet potato" as some South American languages (kuumala -- Polynesian vs. kumara/cumal -- Quechua) is kind of a clue, yes?

The fact that the "vegetation raft" theory persisted for more than a few seconds in the face of this knowledge always astonished me.

Not just nearly the same. It's literally kūmara in Māori.

Hard to imagine what motivated them to keep sailing all that way with no guarantee they would find anything.

But they did. They used a lot of different indication for where islands were - bird migration, ocean currents, etc.

They had already come a very, very long was from Asia to Australia, Fiji, Tonga, Samoa, French Polynesia, Hawaii, etc. Finding land in an impossibly vast ocean was kind of their jam.

Hitting the population limit of your island, and strong cultural norms around exploration.

If you see birds come from that direction, or tides come from that direction with flotsam, then you can bet there is land. Within certain range, if you see specific clouds or tones on the horizon, you can also imply land. Also, if you head that way the Americas are kind of hard to miss.

How do we know they didn't know they would find anything? There is lots of evidence that we have lost perspectives on how to analyse our environment as we have gained new ones through technology.

I think the article alludes to it. First sons world inherit everything so little brother would have to sail out to find new land.

You could say that about almost any explorer ever.

But modern explorers don't expect death if the "nothing" situation comes to pass. These were people that staked their life.

They brought food, they captured water from rain and condensation, and they could fish. Yes it was risky but they had a lot of runway due to their expertise on the water.

Modern explorers also can be reasonably assured there will be enough food to go around next year or the year after if they stay home.

Well modern explorers have the benefit of always knowing that there is a "something", but probably still understand that there is risk in what they are doing. Historically though, plenty of explorers from many different cultures travelled to where there was potentially "nothing". Why would Pacific Island cultures be any different?

Curiosity is a very powerful thing.

Testosterone.

Men and women travelled on the canoes together. Colonisation of islands is difficult if you only have guys eh?

Certainly oral legend of the Māori is mixed crews e.g. “According to some accounts, Horouta was the first waka [=canoe] to make landfall in this region. The captain of the Horouta was Pawa, the navigator was Kiwa. It carried a large crew of men, women and children – as well as a dog named Whakao, belonging to Pawa.”

Having women and children on board isn't necessarily incompatible with the idea that the drive for the insanely risky exploration was fueled by testosterone.

So these days with so many artificial ingredients and ultra processed foods and sedentary habits leading to decreased testosterone these journeys might not have taken place had they had our modern diets [and as child comment adds, lifestyle]?

I'm far from a scientist, but in my observations and reading, lifestyle has a far bigger impact than diet. Hard work boosts testosterone, there was even a study done showing how much it was boosted during chopping wood, for example. Modern folks are sedentary and often overweight, both of which contribute to lower testosterone, likely moreso than diet ever could.

Men today are observably less 'manly' than in the past. But we seem to try to find someone or something to blame other than ourselves.

It seems that phthalates (plastic softeners) are also reducing testosterone.

https://doi.org/10.1093/humrep/dev225

A bit of A, a bit of B.

The modern diet is also very processed and refined. White bread and white rice were not available for mass consumption until industrialization.

Japan's navy solved an issue with beriberi disease after changing the rations from white rice to barley. https://www.atlasobscura.com/articles/rice-disease-mystery-e...

Maybe also selection pressure (which has largely been removed). The men _who_survived_ were more manly in the past.

Perhaps, but I think we can drill down a bit further.

Many third world countries have foods much, much more processed than we do in USA, yet they don't exhibit such effects generally.

My own family is a huge old Irish/German conglomeration...I have 12 uncles and aunts. There's very clear demarcation of millenials vs the older ones, and especially those raised in a rural setting vs urban.

I'd honestly like to see studies of how many, let's say 'metro' men spent summers bucking hay or stripping tobacco as a kid. I did, but I'm clearly less grizzled than my cousins who did such work year round as a kid.

And I don't mean any of this to be insulting. I'm way less manly than my own father, and a millennial who spent childhood glued to screens.

Why do you describe something like bucking hay or stripling tabacco as 'manly' when it was a common activity for women as well in traditional society?

I don't. I just mentioned them because they are very common labor intensive summer jobs where I grew up. Replace with whatever your local variant would be.

Problem is that unless you've actually got symptoms of low testosterone, it's not a big issue. Low T being the cause of men's problems today is a myth.

Or the Americas sailed east and discovered Easter island?

This theory is substantially less likely for a few reasons:

* The predominant oceanic currents in the South Pacific around Rapa Nui come from Polynesia, not South America. So you're not likely to be drifting towards Rapa Nui. Indeed, traveling from Polynesia to South America via Rapa Nui isn't a particularly far-fetched idea.

* Polynesia, and earlier Austronesian antecedents, had a much stronger tradition of long transoceanic voyages. (Austronesians crossed the Indian Ocean and settled Madagascar before Africans set sail from their own coast to reach it).

I think I read somewhere that the DNA studies showed genetic transfer in one direction only, S. America to Polynesia, and not the other way, which seems like a bit of a counter argument.

There are studies which has shown that some Amazonian natives had partial Melanesian ancestry which supports the argument.

If you mean these [0], I think they are talking specifically about a migration route through the Aleutians?

[0] https://www.sciencemag.org/news/2015/07/mysterious-link-emer...

What is more likely, a culture renowned for its seafaring ability and resiliency on tiny islands exploring far beyond their homeland, or a group from a resource rich continent leaving and reaching far despite their lack of experience with naval navigation and at-ocean life?

I would put my money on the islanders being the explorers rather than the mainlanders.

That was Thor Heyerdahls theory and he proved it possible with his Kon Tiki expedition but I think more recently DNA testing has shown that islands (including Easter Island?) has been settled by people from Asia.

(Writing this I realize you might have meant that people from South America went to Easter Island and back, but as far as I know there hasn't been found traces of a strong culture for navigation in South America.)

>traces of a strong culture for navigation in South America

Further, the motives for diaspora were not there. Native south Americans had barely scratched the Amazon. There was so much left to explore and exploit on the continent. Going on a crazy at sea journey just was not necessary.

> Native south Americans had barely scratched the Amazon

The Amazon basin had millions of inhabitants in the 15th century. Population declined precipitously after European diseases arrived, and did not recover to prior levels for 300+ years afterward.

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