[HN Gopher] Radiocarbon dating reveals Rapa Nui not as isolated ...
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Radiocarbon dating reveals Rapa Nui not as isolated as previously
thought
Author : wglb
Score : 44 points
Date : 2025-07-08 02:37 UTC (2 days ago)
(HTM) web link (phys.org)
(TXT) w3m dump (phys.org)
| Hilift wrote:
| "Experts differ on when Polynesian inhabitants first reached the
| island. While many in the research community cited evidence that
| they arrived around the year 800, a 2007 study provided
| compelling evidence suggesting their arrival was closer to 1200."
|
| "By the time of European arrival in 1722, the island's population
| was estimated to be 2,000 to 3,000."
|
| That implies a huge boom and near-total depopulation crash in
| only 500 years.
|
| The total area is 163.6 km2 (63.2 sq mi), but usable area is only
| about 1/2 of that. It is 2,300 miles west of South America and
| 1,100 miles from the nearest island.
|
| "... new findings by archaeologist Terry Hunt of the University
| of Hawaii may indicate a different version of events. In 2000,
| Hunt, archaeologist Carl Lipo of California State University,
| Long Beach, and their students began excavations at Anakena, a
| white sandy beach on the island's northern shore. The researchers
| believed Anakena would have been an attractive area for the
| Rapanui to land, and therefore may be one of the earliest
| settlement sites. In the top several layers of their excavation
| pit, the researchers found clear evidence of human presence:
| charcoal, tools--even bones, some of which had come from rats.
| Underneath they found soil that seemed absent of human contact.
| This point of first human interaction, they figured, would tell
| them when the first Rapanui had arrived on the island.
|
| "Hunt sent the samples from the dig to a lab for radiocarbon
| dating, expecting to receive a date around 800 A.D., in keeping
| with what other archaeologists had found. Instead, the samples
| dated to 1200 A.D. This would mean the Rapanui arrived four
| centuries later than expected. The deforestation would have
| happened much faster than originally assumed, and the human
| impact on the environment was fast and immediate."
|
| "Hunt suspected that humans alone could not destroy the forests
| this quickly. In the sand's layers, he found a potential culprit
| --a plethora of rat bones. Scientists have long known that when
| humans colonized the island, so too did the Polynesian rat,
| having hitched a ride either as stowaways or sources of food.
| However they got to Easter Island, the rodents found an unlimited
| food supply in the lush palm trees, believes Hunt, who bases this
| assertion on an abundance of rat-gnawed palm seeds."
|
| "Under these conditions, he says, "Rats would reach a population
| of a few million within a couple of years." From there, time
| would take its toll. "Rats would have an initial impact, eating
| all of the seeds. With no new regeneration, as the trees die,
| deforestation can proceed slowly," he says, adding that people
| cutting down trees and burning them would have only added to the
| process. Eventually, the degeneration of trees, according to his
| theory, led to the downfall of the rats and eventually of the
| humans. The demise of the island, says Hunt, "was a synergy of
| impacts. But I think it is more rat than we think."
|
| https://en.wikipedia.org/wiki/Easter_Island
|
| https://www.smithsonianmag.com/travel/the-mystery-of-easter-...
| Y_Y wrote:
| They must have been walking around on a carpet of rats at some
| point.
|
| For comparison, NYC has an area of 1223.59 km2 and somewhere in
| the ballpark of 3 million rats (
| https://mandmpestcontrol.com/pests/rats/3-million-rats-in-ny...
| ), which is a lower total density, but also Rapanui doesn't
| have quite the same multi-level infrastructure.
| owenversteeg wrote:
| >That implies a huge boom and near-total depopulation crash in
| only 500 years.
|
| There is a fierce debate on the history of Rapa Nui - whether
| the population was stable until European contact or if there
| was a large boom and bust. The evidence for the boom-bust has
| always seemed pretty strong to me. There are the classic
| arguments of the obvious deforestation, collapse of
| biodiversity, erosion, islanders moving into caves, etc. But
| there is one aspect that is, I think, underestimated: heat.
|
| It is a small, isolated island with cooler weather than most
| other Polynesian islands. The heat really does make a
| difference, it gives you substantially higher energy
| requirements; most of the year mean daily temps are 60s F
| versus 80s on many other Polynesian islands, and the winds are
| strong. You will need both more calories and more heating
| (trees.) Then, consider that the period of collapse would line
| up with the Little Ice Age, which we already suspect to have
| caused severe drought on the island. [0] Cut down a relatively
| small number of trees to burn and now your crops and homes will
| be sprayed with salty, cold sea spray, so you move inland, and
| to move inland you have to cut down more trees!
|
| There are, of course, other causes of the deforestation, but
| there is strong evidence [1] suggesting that the people killed
| the trees, not the rats. Why would you cut down trees? 1) you
| need more agricultural land, 2) building, 3) heat. Spend all
| day on a small island with strong salty sea winds on a cool day
| and you too would enjoy a nice big fire to warm up...
|
| [0] https://eartharxiv.org/repository/view/6509/
|
| [1]
| https://www.sciencedirect.com/science/article/abs/pii/S03054...
| Hilift wrote:
| People killed the trees. The rats ate the tree seed fruit. A
| palm probably produces 200 pounds of seed fruit per year. The
| only native palm was Paschalococos disperta, which is
| extinct.
|
| https://en.wikipedia.org/wiki/Paschalococos
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