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All by Itself, the Humble Sweet Potato Colonized the World: Study (nytimes.com)
41 points by onuralp 8 months ago | hide | past | web | favorite | 19 comments



Some New Zealand ancient DNA experts have concerns about the analysis:

“So, the data that the whole argument is based upon is DNA from one sample that was produced without using standard ancient DNA protocols and analysed without using standard ancient DNA authentication methods. The data presented, to an ancient DNA researcher, ring alarm bells and appear very much like damaged and/or contaminated DNA."

https://www.sciencemediacentre.co.nz/2018/04/13/when-did-swe...


This sounds like a credible alternative to me:

> Dr. Kistler argued that it was still possible that Pacific Islanders voyaged to South America and returned with the sweet potato.

> A thousand years ago, they might have encountered many sweet potato varieties on the continent. When Europeans arrived in the 1500s, they likely wiped out much of the crop’s genetic diversity.

> As a result, Dr. Kistler said, the surviving sweet potatoes of the Pacific only seem distantly related to the ones in the Americas. If the scientists had done the same study in 1500, Pacific sweet potatoes would have fit right in with other South American varieties.

I remember an issue of National Geographic that had a photo montage of about 40 different kinds of potatoes that are still being cultivated in the Andes today. They didn't have any sweet potatoes(1) but I can imagine that in 1500 there were as many different sweet potato variants being cultivated in various places in the new world.

(1) Sweet potatoes are not a variety of potato, so this isn't surprising.


The linguistic similarity they mention at the end is actually even closer: in Maori (and New Zealand English), the word is "kumara".

However, there seems to be some doubt as to whether the word was historically in Quechua, or whether it was introduced later, based on a Polynesian word (e.g. https://anthrosource.onlinelibrary.wiley.com/doi/pdf/10.1525...).


Most likely it was originally Quechua, see Adelaar 1998. “The Name of the Sweet Potato: A Case of Pre-Conquest Contact between South America and the Pacific.” https://doi.org/10.1515/9783110806946.403


kuumala/kumara: in Tonga where kumala is the word used, the locals don’t know how old the word is. Same goes for their use of “delfin” for dolphin, a creature they have surely known since long before European presence. So I bet the kumala name is a recent loan word. They may have had another word in the past now forgotten.


There's also https://news.ycombinator.com/item?id=16825800, but this looks like the more substantive article.




don't they float?


They do, but much like a potato the outer skin contains the germination layer. Exposure to salt water and sunlight slowly destroys this, and salt water dehydrates the inner flesh. They do not survive to germinate.


could the potatoes plausibly be encased in something else, like a mixture of clay, wood, and other detritus from a mudslide? Maybe even a really light, but tough layer of volcanic ash and mud, and then the whole thing is washed out to sea? You only need one lucky tater to make the journey after all. If the mixture of debris is right, it could float and stick together even in water for quite a long time. Ash wood to keep it buoyant, clay as a binder, with the clay baking in the sun. Then it all goes to sea, and protects the spud for enough of the journey that it’s still viable?


I suspect if the potato was encased in ash and mud, floating in average ocean surface temperatures (away from the poles), it would attempt to germinate. Tubers love trying to grow. If it did, it would break apart its case in no time.

That's just a hunch I have. Maybe you're right, and the ash or something in a particular clay would inhibit germination. There are so many variables. It's fun to think about - I often wonder how some plants haven't ended up in certain places over the last millions of years.


A seed transported by bird is more likely in my (pretty uninformed) opinion than a tuber. As a relative of the bindweed it produces a small fruit that is eaten by birds.


Are you suggesting sweet potatoes migrate?


Well, coconuts do - they evolved for the purpose. It seems unlikely you can say the same for sweet potatoes, though.


Only one has to. Floating may not be a bad theory. Can they root after being in salt water for months though?


I was suggesting that, given enough tries (over thousands of years), a few might swim around the world and survive enough to grow. Possibly with some animal assistance.


Not at all! They could be carried.


What? A swallow carrying a sweet potato?




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