Easter Island Palms

[sur4z]

This article is a little over my head but interesting none the less.

The vanished palm trees of Easter Island : new radiocarbon and phytolith data

Claire Delhon ^{1, 2}, C. Orliac

(2008)

Easter Island was formerly covered with palm trees that constituted one of the most distinctive attributes of the landscape. Twelve 14C dates were obtained from fragments of wood and of nuts discovered in archaeological sites and in cracks in cliffs. These dates, which cover a period between AD 1210 and 1440, are mainly centred around the 14th century which suggests that the population of palm trees was still important at this time. The lack of dates after AD 1450 suggests that the palm forest greatly decreased during the 15th century, without disappearing completely, as is proved by the European accounts. The existence of palm trees on Rapa Nui is confirmed by the presence of numerous palm phytoliths in archaeological sediments. Phytoliths are biogenic opal particles produced by plants. Because of their chemical composition, they are usually well preserved even in sediments unfavourable to the preservation of organic remains. Palm (Arecaceae) produce great quantities of phytoliths, including a very characteristic “spherical echinate” morphotype. The morphometric analysis of that kind of phytolith made it possible to improve our knowledge of Paschalococos disperta, the Rapanui extinct palm. The statistical comparison of fossil Easter Island palm phytoliths with phytoliths extracted from various palm species (Jubaea chilensis, Juania australis, Cocos nucifera, various species of Pritchardia) showed that phytolith assemblages produced by Jubaea chilensis are close to those from Easter Island sediments. Nevertheless, because of the differences between the two pools of data, we put forward the hypothesis that more than one species grew on the Island. Moreover, phytolith morphotypes sometimes vary from one part of the plant to another. We investigate the differences between trunk and leaf phytolith spectra, in order to determine which parts of plants are involved in archaeological deposits. In addition to paleoethnobotanical implications, the characterisation of leaves versus stem (which is currently impossible by wood anatomy criteria) will improve the interpretation of radiocarbon data. Indeed, if the trunk is a long-lasting organ that can sometimes be several centuries old, leaves represent a shorter period, and thus are more accurate for radiocarbon dating.

[WestCoastGal]

Interesting. Thanks for the post. Noticed the 2008 date. Is this still the leading theory or research?

Good thing they now think that the stone Moai statutes now really "walked" to their resting places because can you imagine using a Jubaea chilensis as a roller to transport?

[Funkthulhu]

I like that they're doing studies on living palms to determine if the phytoliths are of different morphology from different parts of the tree. Still, even if that were the case is sounds like the morphology and size of the phytoliths are a clear indicator that there were multiple species extant on the island both before and during the occupation by polynesian peoples.

It would be interesting to determine if there is any drastic difference in the phytoliths before and after the arrival of people to give a clue what species (if any) were introduced to the island by humans.

Also, isn't it a pretty safe bet that the island would have more than one species on it? Are there any islands today that have a palmate monoculture?

[Justin]

The island is TINY, and not near anything else. So it wouldn't surprise if they had only one palm species, only two, or even if they never had any. For a volcanic island in the middle of the ocean, when it comes out of the water, it has literally nothing, and then goes from there. Hawaii has numerous Pritchardias, but there are four major islands and several smaller ones, with all kinds of varying elevations, rain shadows, etc. For a tiny island that doesn't have much elevation, it's not that surprising (to me) that there would be a lone species. BTW, there are both Coconuts and Jubaeas there now, which makes Rapa Nui one of the few places with a climate to grow both.

[WestCoastGal]

If there were a few varieties of palm growing there it wouldn't surprise me if someone brought seeds with them to plant when they left their home island. Maybe for the eventual fruit, oil, palm fronds for shelter...

[mike in kurtistown]

Like the previous poster, I am puzzled by the lack of carbon dates before 1210 AD, which might suggest an anthropogenic origin of the Easter Island palms.

[ahicks51]

Like the previous poster, I am puzzled by the lack of carbon dates before 1210 AD, which might suggest an anthropogenic origin of the Easter Island palms.

Or perhaps an absence of archaeological sites prior to 1210, coupled with a paucity of samples from "cracks in cliffs."

I seem to recall there being only two dozen examples of rongorongo, the written language- most of it weathered- after everything else was plundered and destroyed in the 1880s. It stands to reason that there would be few existing archaeo prior to 1210, but I don't have access to the full paper to tell.

Pollen, some nut shells, and root casts. Not much to go on to separate it from Jubaea. But- this paper from 2010 has a lot more on palms, and the palynology of Easter Island.

[mike in kurtistown]

Thanks to the previous poster (#7) for the reference to the 2010 paper. I've read enough to know that it's clear that palm pollen in high percentages is present in lakebed samples going back at least 35,000 years. And present in all but the most recent samples, there being an error margin in dating of of several hundred years. But the authors are not sure whether the entire island was forested, or whether just the areas around two of the three volcanic lakes and along the seashore were forested.

[JasonD]

I vaguely recall recent scholarship on Polynesian settlement arguing for a much later date for the settlement of Hawai`i and Easter Island. 1210 CE might be the date of the earliest-available archeological site because it's near the earliest date of settlement.

[Tyrone]

If you were leaving in a canoe from the South American mainland from somewhere around Chile for an ocean voyage to who knows where into the Pacific, you likely would cram the boat full of Jubaea chilensis seed to keep everyone alive on the journey. If you were lucky enough to find this speck in the Pacific and had some seed left you would likely plant a few, provided you had another food source. This could have happened way before the Polynesians found the place. The other option is birds dispersing the Jubaea seed there, but I'm not sure if that's possible. They're a big seed.

[Mike in Nelson]

I wonder if the Island had its own unique palm species like New Caledonia etc?

[JasonD]

John Dransfield named the endemic extinct palm Paschalococos disperta.