Easter Island (parable) arguments

From SourceWatch
Jump to: navigation, search

This page is for discussion of Rapa Nui (Easter Island (parable)) alternate parables & arguments, mainly Hunt and Lipo vs. Diamond, and the evidence pro, con, and wanting.

The big picture still looks like overexploitation, but when you get down into the details it does get messier, as not all the evidence marshalled to support the competing interpretations is strong enough to do so. Hunt and Lipo are arguing a case, not presenting and weighing the evidence. They misrepresented the rat-gnawed palm nut research, then one implied it didn't matter since the findings didn't affect their "it was both" interpretation, which itself is moving the goalposts from the book's dustjacket argument. Diamond uses an overinterpretation of a pilot dig to bolster his assertion (which may well be correct, from other grounds) that porpoises disappeared from the islanders' diet; H&L overinterpret in the opposite direction to argue they didn't. Finally, there appears to be no good evidence for cannibalism.

The above summation is subjective; please read the back-and-forth below and assess for yourself.

Arguments, counter-arguments, counter-counter-arguments...

Cause of deforestation

Hunt and Lipo imply mostly rats

Hunt and Lipo argue that the forest of Rapa Nui was made extinct mostly by rats. (Caveat: Hunt, in email, now says the cause was humans plus rats, and does not assign a "mostly" weighting. This results in the same view offered by Diamond in Collapse, ostensibly at least. I say "ostensibly", since the Statues dust jacket exonerates humans, saying they "did not devastate the palm forest", and also since at the end of Chapter 2, Lipo and Hunt do imply that the islanders were not to blame, saying that if the islanders "had, in fact, had so little to do with [the forest's] depletion, ...[then it's time to rethink the rest of the story].")

Hunt and Lipo's arguments for rats as the culprit are:

  • ...that deforestation began when humans-plus-rats arrived, which Hunt and Lipo say was later than originally thought. But see Bahn and Flenley below on "Timing of islanders' arrival" section, on the Anakena beach unconformity.
  • ...that rats have been shown to eat plant parts and change biota elsewhere (Campbell and Atkinson 1999). But Bahn, in Nature, says that even tree species which coexist with rats on other islands disappeared on Rapa Nui.
  • ...that the Ewa Plain [rat-influence] evidence, in Hawaii, fingers the rats - that the original view was that its deforestation was human-caused via slash and burn, but then Steve Athens found that deforestation preceded [presumably human-occupation-caused] fire, and rats were contemporaneous with deforestation.(Reference: HL-S). (Flenley and Bahn's 2011-05 RNJ review of Statues counterargues that "The evidence for this is from the sediments in a coastal pond on the exposed SW coast of Oahu, where the prevailing wind would be expected to carry away most of the evidential charcoal." I haven't explored this further, with those who could assess it.)

Arguments against rats being main palm extinction cause

  • Evidence of initial regeneration of palms in a burned area was found, indicating that the rats weren't preventing regeneration. (Source: Mieth & Bork 2009)
  • Evidence of palm stumps burned and cut (Source: Bahn 2011, Nature review)
  • Bloom points out that rats couldn't kill adult palms: "Hunt and Lipo have to do a very large handwave (“died of old age”) to explain the rapid disappearance of all of the [adult] palms (which we would normally expect to be long-lived regardless of exact species, and very, very long-lived if they were close relatives of the Chilean ones")
    • But Hunt in email doesn't do this handwave, saying, "Rats ate nuts, people burned forest for agriculture....".
      • But Hunt and Lipo's book Statues, p.32, does say, "nor was the story one of people recklessly cutting down the last tree".
        • It's known that people did cut down trees, since stumps have been found.
  • Most of the hundreds of other Polynesian islands [which also had rats]... did not end up deforested. (Diamond 2011-09L)
    • Hunt and Lipo respond (from Statues) that each island is different.
  • Over 90% of the [entire - see Mieth and Bork 2009] preserved palm seeds outside caves were not gnawed by rats. This is more relevant evidence than the extremely high within-cave palm nut "gnaw prevalence", which Hunt and Lipo favor, since the nuts in caves would be exposed to rats for an unnaturally long time (Mieth and Bork 2009 ).
    • Lipo and Hunt made an opposing claim: they argued that Mieth and Bork's claim had been based on nut fragments, not whole nuts, and that when "reassembled", all the M&B nuts would be rat-gnawed. (Lipo and Hunt 2011-10L) (Here, Lipo and Hunt said, "We were well aware of the work of Mieth and Bork as we did our work. But we were also aware of the fact (which Diamond fails to point out) that Mieth and Bork based their claim on nut fragments, not whole nuts. ... the problem [with] using Mieth and Bork whose estimate of 10% rat gnawed fragments [is that it] implies that most nuts (if they were counted whole) were actually gnawed by rats.")
      • But Mieth disagreed vehemently with Lipo and Hunt's report on M&B's methods, saying, "The phrase in our paper (Mieth and Bork 2010, Journal of Archaeological Science, page 423) is very clear: "Among more than 200 COMPLETELY preserved and charred nutshells .... less than 10 % had the teeth marks of rats." It is NOT less than 10 % of nut fragments. It is less than 10 % counted for whole nuts!" (source: 2011-11-27 email)
        • Asked about the misinterpretation, Hunt said that a) the palms went extinct due to effects of both rats and humans, the cause wasn't black and white; b) the M&B paper wasn't clear and its data not conclusive (e.g. that perhaps these nuts (from Poike Peninsula) were charred shortly after falling, before rats could reach them).
    • Lipo and Hunt offer an opposing claim: that Tainter 2008 says "but every seed discovered had been gnawed...and could not have germinated (Flenley and Bahn 2002:160, 161)"
      • But these were most likely the seeds in caves, which aren't going to be disturbed by weather or permitted by moisture to germinate, so rats would have eons to chew on them.
      • Back in 2002, F&B did say, "it seems likely that ...the Polynesian rat ...may have prevented regeneration and ultimately contributed to ...[the palm's] extinction. But it was human activities that actually removed the trees themselves."
        • But this was in 2002, before Mieth and Bork's paper finding little gnawing of non-cave palm nuts.
    • 24 other (tree?) species also became extinct on Easter Island, most of which are not known to suffer seed predation by rats; and they continue to exist in the presence of rats on other Polynesian islands.

Islanders' demand for wood

Related to wood for canoes

  • "The palm trees, at least, were not a likely source of wood [for canoes] due to their fibrous interior and relatively thin, brittle bark." (H&L 2009 PacSci p. 605)
    • (Counterargument?)

Related to how statues were moved

  • Hunt and Lipo also argue that the forest was not made extinct by islanders, saying:
    • Islanders did not need wood for moving statues (Source: H&L S) (But "sleds were probably more likely than rollers, using palm leaves under the runners to grease the way,"(Bloom) and "levers would certainly have been needed, and use of sleds and/or rollers remains likely in some cases." (F&B RNJ review))
      • Statues were not rolled down the hill but “walked” upright (neke-neke)
        • This orientation has "some plausibility for short-distance transportation, but it seems highly unlikely that fragile and heavy statues could be easily moved distances of over 10 km by this technique without severe damage." (F&B RNJ review)

Did deforestation help or harm the islanders?

  • H&L argue that deforestation helped the islanders, saying:
    • Deforestation provided more room for agriculture (H&L S)
      • Yet early agriculture occurred underneath the palms (Mieth and Bork 2009)
    • Contrary evidence indicating that deforestation harmed the islanders:
      • Islanders were using leaky canoes made of wood pieces
      • Islanders begged visiting ships for canoe wood (F&B 2002 p. 159)
      • Islanders resorted to sugarcane scraps for fuel, because of disappearance of native plant fuel (Diamond 2011-09L)
      • Disappearance of oceanic fish and mammals from the diet, likely because there were no trees left for building seaworthy canoes to harpoon them (Diamond 2011-09L)
        • See "Dietary shift -- archaeological evidence" section below; some of it is weak.
  • Statues were adaptive
    • Contrary evidence:
      • Statues may have been due to misplaced cultural focus: the islanders were reportedly fascinated with seafarers' hats
      • Signs of wish fulfillment: the statues made, especially their bellies, got bigger over time
  • Islanders were good stewards of the land
    • Used lithic mulching on surface, to reduce evaporation
    • Buried rocks for fertilizer below the surface
    • Built rock "cloches" (manavai)

Conflict among islanders

  • Hunt and Lipo argue that the islanders were peaceable
    • But obsidian mata'a appeared
      • They were shaped for scraping, not for weaponry (H&L)
        • Flenley et al. 2007 disagree: Forster in 1774 said, "some...had lances or spears made of thin ill-shaped sticks, and pointed with a sharp triangular piece of black glassy lava"; and Metraux 1940 "was told by the Rapa Nui people that the mata'a were used as weapons", and shows hafted examples which Ayres et al 2000 says "are known in ethonological collections." They sum it up as "mata'a...were the Swiss Army Knives of ancient Rapa Nui"(Flenley et al. 2007)
    • Owsley 2003 on BBC said they were a people at war with each other. He found much skeletal trauma in 600 bodies.
      • But (say H&L) Owsley 1992 said little fatal trauma was found.
      • Lipo 2011-11-14 P3 said there was no evidence for widespread lethal warfare.
      • Owsley 2011 pers. comm. said to wait until new data have been analyzed.

Timing of arrival of islanders

Note: this section is incomplete; someone could delve into this further.

  • Significance of the question: if there were centuries before deforestation, rats would not have been the cause.
  • Evidence for early arrival: (Bahn, Flenley) Rano Kau (crater) core pollen studies estimate around AD100
    • But (H&L) the arriving population would not have settled there.
  • Evidence for late arrival: (H&L) dating of items found in the Anakena Beach excavations.
    • But (B&F) argue there's an unconformity, and centuries are missing.
  • H&L give as evidence for late arrival: other islands' dating shows later dates, circa 1200 AD (H&L?)
  • Islanders' arrival date is earlier than the Hunt and Lipo estimate of 1200AD based on radiocarbon dating at Anakena beach. B&F say that a sand dune near sea is ideal if you want a late date (since sea level has risen, so the current dune will have formed atop earlier subsoil, creating an unconformity of "perhaps several hundred years", and to ignore the unconformity is to use absence of evidence as evidence of absence. (At the base of the Anakena excavation, the unconformity "is a change from blown sand (above) to clay (below)"(source: CWA 48))

Population size

  • What was the population peak, before European contact?
    • Hunt 2006 says, "There is no reliable evidence that the island's population ever grew as large as 15,000 or more"
    • Lipo 2011-11-14 P3 says there is "no evidence for the 10,000+ population that has been argued to have once lived on the island."

Diamond: Island culture collapsed

Evidence offered by Diamond for collapsing island culture:

  • "Starving"-shaped moai (Diamond 1995)
  • and...:

Cannibalism: Diamond yes, others no

  • Cannibalism (cracked long bones in garbage middens, plus folklore, said Diamond)
    • Counter: Bahn (in F&B 2002) says there's not good evidence for such cannibalism. (See incipient 3rd edition of book, whose title will revert to "Easter Island, Earth Island".) Also, folklore is generally considered colorful, but not reliable without other supporting evidence. (F&B 2nd ed?)
    • Counter: ship log says they were healthful, and that there were abundant fish (Peiser 2005)
    • Counter: the first mention of this cannibalism comes from a sensationalised hoax published in a French tabloid newspaper in 1845, which alleged that native cannibals had tried to eat a French ship captain. Also, it's an old ploy by Christian missionaries to show the need for conversion
    • Human bones were found in garbage pits, cracked to extract the marrow. (Diamond; ref?)
      • Counter: (Lynas(?)) couldn't find any evidence for this in the academic literature
    • Lipo 2011-11-14 P3 reports "no evidence for cannibalism" and Bahn concurs (2011, pers. comm.)

Dietary shift -- archaeological evidence

  • What is the evidence of dietary shifts over time? Relevant information includes the faunal assemblage of bones, from a site 100m inland from Anakena Bay ( Hunt and Lipo 2009PacSci); H&L said these bones show a U shaped distribution, which Steadman said is perhaps from increased sand deposition in middle periods. (Steadman, Asian Persp. 1994, p.90)
    • Diamond says dietary changes occurred: islanders went from eating sea life to chickens.
      • "In the bone deposits in early Easter Island middens, the most common food item was dolphins. Yet dolphins don’t come close to the shore of Easter Island. In order to catch or harpoon dolphins, the islanders would have had to go far offshore in dugout canoes. This is the only Pacific Island diet in which dolphins played a big role." (Diamond 1995)
        • H&L disagree that dolphin prevalence in diet dropped, saying:
          • that Steadman's dig found no drop in dolphin prevalence, finding a U-shaped distribution over time.
            • But if you look at Steadman's data, from what's described as a pilot experiment, they do not seem clear cut enough for the interpretations constructed from them. The U-shaped distribution that H&L present in graphical form (PacSci 2009) only appears in the pooled data from squares 1-3 of Steadman's dig, whereas for the three layers of Square 4, which admittedly went only half as deep, each upper one has fewer bones than the one beneath. Plus from Steadman 1994 we can't tell whether Squares 1-3 varied in "prevalence pattern" from one another. And raw numbers of bones seems to be a very un-independent measure, as a single animal would yield many.
            • Bahn disagrees that dolphins remained in the diet, saying "...there were no dolphins...NB Steve Fischer states (in "Island at the End of the World", 2005, p. 20) that the indigenous name for "porpoise" disappeared centuries ago, as none was left locally" (email 2012-03)
            • I think the site Steadman excavated is too variable to draw meaningful "shift" conclusions from. S. just fits the data into a picture formed by other data, saying:
              • "Bones of delphinids are rare, in many cases nearly absent, from Easter Island faunal assemblages younger than c. 500 B.P. (Ayres 1979, 1985). [Discussion of various lines of evidence, including deforestation dates, cut]... Thus layer I and uppermost layer IIa of our excavation may have been deposited only a century two before the near elimination of marine mammals from the diet of prehistoric Easter Islanders. The decline in exploitation of marine mammals must have been precipitous, because even in the upper 20 cm of our excavation delphinids remain the highest ranked vertebrate category (Table 7)."
                • Where was Ayres looking, and was the site comparable? (If in caves far from the beach, would you expect to find fewer bones of a large sea mammal?)
          • "What pattern of bone prevalence has been found in other Easter Island digs?
          • H&L assert that dolphins didn't require deep-sea harpooning, and were likely taken "using stones struck together in the water to disorient the animals echo- location system and drive them into shallow waters, either from small canoes or by people in the water, and then taking them by hand with little or no specialized technology (e.g., S. Aswani, personal communication, 2007; Bloch et al. 1990; Porcasi and Fujita 2000; Takegawa 1996)."(H&L, RNJ 2007)
            • Bahn disagrees (email 2012-03), saying that "...no mention of any such technique [is] in the island's folklore or the data collected so carefully by Routledge, Metraux et al -- hardly surprising, as they were no longer catching dolphins!" and "H/L's claim about someone using this technique on the island in the early 20th century is worthless... they give no source for the info,...[and] (even if it's true...) the technique could have been learned from books or anthropologists".
  • No sea turtle bones were found in the 1994 excavation, although the fallible search engine Google seems to report turtles near the island in current times. How should we interpret this? Perhaps they were the #1 overharvested animal, eliminated right at the beginning; perhaps the bones were deposited elsewhere; or perhaps the data aren't clear cut enough to be meaningful.
    • Were sea turtle bones found in other Easter Island digs?

Overall criticism of "Statues" book

These quotes are from Bahn and Flenley's draft "Statues" review for Rapa Nui Journal:

  • "[Science involves testing hypotheses] against observations. The trouble with observations is that selecting them, accidentally or deliberately, can bias the conclusions. The new volume by Hunt and Lipo is a striking illustration of this phenomenon."
  • "no mention [by H&L] of the bird-man cult at Orongo."
  • "no mention is made [by H&L] of the fact that all the basic foundation stones of the authors’ scenario -- such as the supposedly late date for human arrival, the alleged devastation of palm trees by rats, the lack of evidence for weapons or violence on the island -- have been challenged and refuted in recent years, mostly in papers in this [Rapa Nui] journal"
  • The coverage of Heyerdahl was telling.
    • Was there any reference to Heyerdahl’s early work on Easter Island in Lipo and Hunt’s book?
      • Yes, but it was cursory. Whereas F&B 2nd edition went into detail showing that Heyerdahl's 'scientific' thinking was not scientific, Hunt and Lipo in Statues are marshalling evidence to bolster their thesis, so they say little about Heyerdahl.

Consensus? (who shares these views?)

Diamond and Hunt and Lipo all claim the support of the consensus. How many people actually study Easter Island (it must be a small and well-defined group) and what do they think? How is a lay person to check this? )

  • Diamond says: "Hunt’s and Lipo’s conclusions are considered transparently wrong by essentially all other archaeologists with active programs on Easter Island."
  • Tainter says that researchers favoring Diamond's account include: Kirch 1984 and 2000; Ponting 1991; Flenley and Bahn 2002
  • Tainter says those holding opposing views include: Hunt, Rainbird, Tainter and van Tillburg (who dismisses the whole business as ‘‘scary parables’’ (1994:164))

Miscellany

What did Hunt and Lipo say about... (asked at Planet 3.0)

  • Did Hunt and Lipo mention disappearance of fish and sea mammals and bird bones from diet?
    • Yes on mammals; bird bones, though, they might not have mentioned.

Questions not bearing on the parables' correctness, from curiosity only

  • Do rats typically eliminate bird life from Rapa Nui-sized islands?
  • Are Jubaea seeds human-edible? Answer: apparently yes, in extremity.(reference?)
  • How and when would the palms have arrived from Chile?
    • What are the prevailing ocean currents between Chile and Rapa Nui like? (If we just look at the currents, would the palm nuts have been able to float there from Chile? Do palm nuts float?)
      • Answer, from reading Flenley&Bahn 2nd edition: the currents (today, at least) don't run from Chile to Rapa Nui, they're circular, with Rapa Nui out of the way, in the center. (Do these currents change cyclicly, such as between El Nino and La Nina?)
    • F&B 2002 (page 20-21) also note that it may have been easier to reach the island during ice ages, when sea level was lower and current sea mounts would have provided "stepping stone" islands; plus typical maximum wind speeds may have been higher then.
  • Given the Chilean Wine palm's use in Chile, is there evidence, including from folklore, that fermented beverages were made from this palm on Rapa Nui?

Information that's incomplete

  • SB wanted a book chapter from Owsley, since it's unlikely to be otherwise available. Was this the 1994 book?
  • SB wanted to know, from Mieth, 2011-11: (Still?)
  • Do the root casts you found say anything about the type (shape) of palm?...[the casts] seem a little too vertical to be associated with a spreading (i.e. non-trunked) variety of palm. How do they compare to Chilean Jubaea roots?
  • any pointers to research on erosion other than M&B? It looks as if most of their work was limited to a peninsula, albeit a large one, so what about work elsewhere?
  • What's the likelihood or evidence that slash and burn would have led to a food surplus then followed (once the trees were gone and the nutrients depleted) by a shortage (compounded with a nutritional deficit)?

unchecked references

  • Sergio Cristancho and Joanne Vining (2004): Culturally Defined Keystone Species, Human Ecology Review

("It has been suggested that the eco-disaster on Easter Island was causative in the collapse of the human society, especially related to the disappearance of the Chilean Wine Palm cousin.(Cristancho)" [1])

Chilean Wine Palm, Jubaea chilensis

Since the Easter Island palm was likely closely related to the Chilean Wine Palm, Jubaea chilensis, the history of what's happened to the Chilean palm may hold lessons about the Easter Island one.

Vulnerability

Overharvesting for the sap has left J. chilensis threatened in Chile. (González (1998). Jubaea chilensis. 2006 IUCN Red List of Threatened Species.)[2]

Uses of J. chilensis

Reportedly:[citation needed]

The palm heart is edible, but requires cutting down the tree
The tree can yield as much as 400 liters of sap for palm honey, but to get this much requires cutting down the tree, then letting sap ooze out, over several months
The palm honey can be fermented into an alcoholic beverage
The fruits are edible, and sweet
The nuts are edible, and can be used as nuts
Fronds can be used for thatching roofs
Trunks can be used for making canoes

Growth habits

J. chilensis is:

Unusually cold tolerant for a palm. So it would be likely to be suited to Rapa Nui, which is cold for a Polynesian island.
Very slow growing.
The trunk attains considerable width before the tree gains much height. (Perhaps this would let it be cut down while subadult, and still make a canoe.)

Related SourceWatch articles

External resources

References


Almost all the following references are available online, except for the books.