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from the whatever-you-do,do-NOT-ask-for-help-from-Montezuma dept.
Easter Island Inhabitants Collected Freshwater from the Ocean's Edge in Order to Survive:
Ancient inhabitants of Rapa Nui (Easter Island) maintained a society of thousands by utilizing coastal groundwater discharge as their main source of "freshwater," according to new research from a team of archaeologists including faculty at Binghamton University, State University at New York.
The team, which included Binghamton University Professor of Anthropology Carl Lipo, measured the salinity of coastal water around the island of Rapa Nui, in order to determine whether or not the water close to the shores had a salt concentration low enough for humans to safely drink.
The process of coastal groundwater discharge makes it possible for humans to collect drinkable freshwater directly where it emerges at the coast of the island.
By measuring the percentage of salt in the coastal waters, and finding it safe for human consumption, and by eliminating other options as primary sources of drinking water, the researchers concluded that groundwater discharge was a critical factor in the sustenance of the large population the island is thought to have harbored.
"The porous volcanic soils quickly absorb rain, resulting in a lack of streams and rivers," Lipo said. "Fortunately, water beneath the ground flows downhill and ultimately exits the ground directly at the point at which the porous subterranean rock meets the ocean. When tides are low, this results in the flow of freshwater directly into the sea. Humans can thus take advantage of these sources of freshwater by capturing the water at these points."
Lipo said the freshwater mixes with the saltwater slightly, creating what's called brackish water, but not enough for the water to contain harmful levels of salt to human consumers. It does, however, mean that the islanders rarely used salt on their foods, because the water they drank contributed so drastically to their daily salt intake.
I wonder how the inhabitants found out where and when it was safe to drink the water?
(Score: 4, Insightful) by Snow on Friday October 12 2018, @03:30PM
Just going to go out on a limb here and guess that they tasted the water running into the ocean at low tide time and it wasn't as salty as the ocean water?
(Score: 4, Informative) by CZB on Friday October 12 2018, @03:50PM
Once one kid licks the poison dart frog and dies, you tell everyone about it and now you can start experimenting on animals.
(Score: 5, Informative) by JoeMerchant on Friday October 12 2018, @04:12PM
Like the Anasazi who preferred round bowls over square ones - you notice that more people die after eating from square bowls (because the crevices harbor bacteria, but they didn't need to know that part.) As for salt in the water - once you know, that's something you should be able to tell by taste, most of the time.
Florida used to work this way, too... rainwater on the peninsula and islands would create a freshwater "lens" that actually extended out into the sea some distance. When my dad was a kid (early 50s), you could dig a shallow hole (less than 3' deep) almost anywhere and get fresh, drinkable water.
Power pumping of groundwater meant that by the 1980s, shallow wells had to go down 15' or more, well below the "hardpan" layer that used to mark the seasonal high groundwater mark, hardpan is iron oxide - rust and it accumulated in a layer an inch or so thick, usually just a foot or two below the surface, throughout much of central Florida.
Today, due to continued groundwater pumping, salt water from the coasts has intruded miles inland in places, sickening deep rooted trees that aren't salt resistant - and didn't need to be because the land they were growing on had been salt free for thousands to millions of years. Shallow wells are too salty to water most grass with along much of the coast now.
Of course, that's better than the Houston area where groundwater pumping has led to a phenomenon called subsidence: the land literally sinks into Galveston bay when the water is removed from underneath it. Our house there started at 30' above sea level in the 1960s and was down to 19' before they got the pumping under control in that area. Some neighborhoods have been completely condemned because they've sunk so low that they flood on an ordinary high tide.
As for Rapa Nui - it's still pretty sparse, populationwise, they should be in good shape for natural rainwater collection more than meeting their fresh drinking water needs. Of course, today they can sink wells - if they're smart they won't put the well casings down below sea level so that they suck air before they start saltwater intruding their natural source of drinking water.
Україна досі не є частиною Росії Слава Україні🌻 https://www.pravda.com.ua/eng/news/2023/06/24/7408365/
(Score: 2) by Gaaark on Friday October 12 2018, @04:39PM (4 children)
https://www.newsweek.com/easter-island-heads-mystery-solved-rapa-nui-drinking-water-1161827 [newsweek.com]
This ^ is saying that the Easter Island 'heads' were placed near fresh water sources... so there were a lot of fresh water sources on the island not near the ocean?
And why build huge structures just to show "hey, fresh water!"...why not just a stone marker: easier to build and place (i'm thinking cairn or inuksuk)
--- Please remind me if I haven't been civil to you: I'm channeling MDC. ---Gaaark 2.0 ---
(Score: 4, Interesting) by urza9814 on Friday October 12 2018, @05:16PM (1 child)
Maybe the heads weren't markers exactly; maybe they thought the heads needed to drink too, or that the heads would encourage the gods to give some blessing to the water source?
I'm also now a bit curious about any process which could have made them believe that the heads would help produce water. I mean there's always the possibility that such a belief could be driven purely by religious ideology...but you throw a massive heavy rock onto soaking wet ground and there's likely going to be some water that pools around it, either from the weight compressing the ground so it can't absorb as much, or the weight causing a depression which collects and retains a small amount of water. If they built a big head or two to worship, and discovered the base of the heads seemed to always be wet, then they might conclude that the heads create water. If fresh water is that scarce, you'll probably try all kinds of crazy things to get more.
(Score: 0) by Anonymous Coward on Saturday October 13 2018, @02:09AM
Maybe the heads were liberals and the Islanders drank the tears.
(Score: 2) by JoeMerchant on Friday October 12 2018, @08:47PM
You live on an island with plenty of food, no serious animal predators or human threats (until the Europeans arrived) - you've got a LOT of time on your hands, carving heads may have turned out to be a 1000 year fad to be replaced by some other fascinating passtime, if that Frenchman hadn't introduced sheep grazing to the island and completely wiped out the ecosystem.
Україна досі не є частиною Росії Слава Україні🌻 https://www.pravda.com.ua/eng/news/2023/06/24/7408365/
(Score: 2) by driverless on Saturday October 13 2018, @10:36AM
You'd want to have your head near a fresh water source, otherwise how would you flush it?
(Score: 2) by bob_super on Friday October 12 2018, @05:31PM (4 children)
The researchers figured out that they could collect freshwater that way.
Not that they DID.
Title is drawing conclusions that the research does not support.
For all we know, maybe there was a change in oceanic currents or rain patterns, and the islanders were perfectly fine surviving on then-abundant rainwater collection.
(Score: 0) by Anonymous Coward on Friday October 12 2018, @07:02PM
Most pacific islands (in the western pacific anyway) have a dry season where it can go months with no rain
(Score: 2) by JoeMerchant on Friday October 12 2018, @08:51PM (2 children)
Researchers love to imagine the past... they can make up stuff all day long.
I don't think Rapa Nui is quite tall enough to deflect the trade winds up the way Oahu and the other Hawaiian islands do to get a year-round reliable rainfall, so... imagine away...
Україна досі не є частиною Росії Слава Україні🌻 https://www.pravda.com.ua/eng/news/2023/06/24/7408365/
(Score: 2) by captain normal on Friday October 12 2018, @09:08PM (1 child)
Rapa Nui elevation is over 500 meters quite sufficient for clouds to build up and cause rain.
"It is easier to fool someone than it is to convince them that they have been fooled" Mark Twain
(Score: 2) by JoeMerchant on Friday October 12 2018, @10:34PM
Yeah, seems like 500m should do the trick... I've been in the "rainy part" of Oahu, and read extensively about similar areas on the big island (MUCH higher than 500m there...), the photos I've seen of Rapa Nui have never shown places like that, it's more rolling and smooth.
Would be nice to have the time to visit personally, as part of a South Pacific tour that doesn't involve naval service....
Україна досі не є частиною Росії Слава Україні🌻 https://www.pravda.com.ua/eng/news/2023/06/24/7408365/
(Score: 3, Funny) by NewNic on Friday October 12 2018, @05:43PM
Desperation?
lib·er·tar·i·an·ism ˌlibərˈterēənizəm/ noun: Magical thinking that useful idiots mistake for serious political theory