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Top articles Febuary 2011: Wilmshurst et al., High-precision radiocarbon dating shows recent and rapid initial human colonization of East Polynesia

A German version can be found here.

I wish journal editors would insist on short titles for articles *sigh*. But anyway, my second article in the top 3 list is a publication on the colonization of Eastern Polynesia. Four top-class scientist came together to re-examine and evaluate radiocarbon data to get a better picture of the colonization of Eastern Polynesia: Janet Wilmshurst from the government owned Landcare Research, an environmental and research organisation in New Zealand; Wilmshurst is probably best known for her work on Pacific rats but has a wide field of interests, Terry Hunt from the Anthropology Department at University of Hawaii, who is engaged in ongoing research on Rapa Nui, Carl Lipo from the Department of Anthropology in Long Beach and co-founder of the IIRMES institute whose  interest in development of theoretical models to study patterns of change clearly showed in this article, and last not least Atholl Anderson from the ANU college of Asia & the Pacific, who is currently directing a major program on Initial Colonization in the Indo-Pacific Region.

There has been a long debate about how and in which time frame Polynesia has been settled with various partially contradicting theories. To address the conflicting chronologies Wilmshurst et al. reverted to a simple yet as it showed, extremely effective method. They sighted the available radiocarbon dates and sorted them into reliability classes. The most reliable data (which the authors named “class 1”) from short lived plants and terrestrial bird eggshells with marginal errors (to circumvent the substantial wiggle in the calibration curve) were then contrasted to less reliable radiocarbon dates, partially taken from samples without any connection materials or commensals like the Pacific rat.

This was the general view of colonization dates for Polynesia (photo from a poster display at the Bishop museum, Honolulu):

 Presuming a starting point in Samoa and Tonga from which the settlement of the Eastern islands started around 800 BC (Wilmshurst et al. 2011, 1818) Wilmshurst et al. could demonstrate that class 1 data had a very short chronology of settlement for all islands including far off ones like Rapa Nui and New Zealand. In short, the authors could establish two migrational phases: a first one to the Society Islands and possibly as far as Gambier at around AD 1025 to 1121 (orange shading on the map) and a second one to every other island in East Polynesia at AD 1200 to 1290.

Wilmshurst et al. 2011, fig.1

Their findings will have an immense impact on studies of settlement patterns in Polynesia. Some chronologies could be confirmed (e.g. New Zealand and Rapa Nui) other colonizing chronologies were shortened and pushed back in date by several hundred years (e.g. the Marquesas, Hawaiian archipelago). The most astonishing result from their study is the uniform timing of the expansion to even the remotest islands like Auckland Island, Hawaii, or Rapa Nui.

The authors then offer different cultural based explanations for the new settlement chronology like population growth, purposeful explorations with the help of technical innovations but also environmental factors or disasters; they here mention the peak El Niño in the 13th century but one can also think of volcanic eruptions although the source eruption for the AD 1259 eruption is still unknown and the Kaharoa, New Zealand eruption dates to the early 14th century and is therefore too late to be taken into consideration.

In a final point they address problems that need urgent reconsideration in respect of the new data set, as there are:

  • introduction of sweet potatoes
  • linguistics
  • artefact similarities
  • human impact on island ecosystems (deforestation, plant and animal extinctions)

Their list could be expanded to genetics (cp. Brewis et al. 1995, Asia Pacific J Clin Nutr 4, 361-5), appearance and stylistic of monumental architecture, dating of rock art to name but a few. There is hope,  that this will be a stimulus to new research into these problems in order to re-analyse present conceptions.

Overall an excellent article that showed how you can make a big step forward in a stagnating topic just by reviewing radiocarbon dates. I was very surprised to find that five islands completely lacked class 1 data and apart from New Zealand reliable radiocarbon dates are the exception instead of the rule. It also reminds us to question the reliability of C14 dates anew when trying to establish cultural development over time.

Only two minor points of critique are left on my side. One is the idea of el Niño events as driving force behind the direction of colonization. Already in the first phase migrations spread considerably to the east, while only very mild el Niño effects have been described for this period (Crowley 2000, Science 289, 2707; Mann et al. 2003, Eos 84, 256-8); The second phase is marked by a spread not only towards the east, but also towards the north and southwest. Since colonization happened within a very short period of time as the authors have demonstrated, it is unlikely that increased westerly and/or easterly winds could be responsible alone.

The second is the attribution of the island of Rapa Nui to the second phase of colonization. In fig . 3 of the article they compare the radiocarbon dates and Rapa Nui has nearly as early dates as Gambier and the Society islands. In my view they could also qualify for the early phase. Besides, if we are considering the normal oceanic circulation

 (see picture), then the equatorial counter current would have brought a maritime sailor right to the border of the American continent and hence also possibly to Rapa Nui.

 I want to conclude with a citation by the authors:

“…previously supported implications that there was a long period of relatively benign interaction among humans, rats, dogs, pigs, and indigenous vertebrates now need revision, as our refined model of colonization chronology suggests that impacts had to have been immediate, severe, and continuous.”

Maybe we can learn something for our future, because this is exactly what human impact always seems to be: immediate, severe, and continuous.

Full citation of article: J M Wilmshurst, T L Hunt, C P Lipo, and A J Anderson, High-precision radiocarbon dating shows recent and rapid initial human colonization of East Polynesia, PNAS 108 (5), 2011, 1815-20.

This article is available online through the PNAS open access option.


Top Articles from February 2011: Potter et al., A Terminal Pleistocene Child Cremation and Residential Structure from Eastern Beringia

It all started as an archaeological dream. This is exactly what happened to Ben Potter from University of Alaska in Fairbanks and grad student Joshua Reuther from Universtiy of Arizona, Tucson. On their last day of exvcavation at the dune site next to the river Tanana they came across a human skull. A dream story indeed. Several authors from both universities reported this sensational find in Eastern Beringia, Central Alaska in Science magazine in the 25th Feburary issue.

The cremated bones of a child were found in a pit-hearth inside a construction at the Upward Sun River Site (USRS).  Although there is some criticism from my side, mainly on the way it was presented, it is without doubt a discovery of enormous importance. Few human reains are known from the period when the Beringian Sea was as low as to allow human traverse from Siberia to North America nor in the following time of deglaciation.

A particular dearth exists on the Eurasian side. Only one site with human remains from that time period are known from Ushki Lake, Island of Kamchatka, Russia. On the North American side (according to the authors) only one cavesite is known to contain human remains from this time period (On-Your-Knees Cave) but this site is dated to 9200 BP (marine reservoir effect considered) and thus roughly 1000 years younger. USRS is radiocabondated to 11,500 cal BP from charcoal samples of the pit fill and pit base).

An approximately three (± 1) year old child was creamted on a pit-hearth. From the preserved bones, the child seemed to have been still aproximately in situ, it could be concluded that the child was placed on the fire in a supine position, only slightly inclined towards the right hand side.  One species of the fuel source has been identified as poplar (Populus balsamifera). Underlying samples were contemporaneous with the fill. Identified fauna from the pit-hearth included about roughly one third salmonids, one third voles, a quarter squirrels and some minorly represented species like hare and grouse. Whole animals were deposited in the pit-hearth but the squirrels seemed to have been cooked. The pit must have been backfilled soon after the cremation event and thus facilitated the excellent preservation of the cremation and animal bones. The event must have taken place in mid-summer, based on unfused epiphyses of squirrels and the salmon present. Directly associated with the semi-subterranean building were 350 lithic artefacts (mostly tertiary flakes related to tool maintenance) in a concentration to the east end of the building. apart from two small ochre fragments within the pit-hearth, no items that could be described as grave goods were found in the hearth.

Potter et al. 2011, Science 331, fig. 3

The authors then try to put this cremation into context which proves difficult since no remains were found within houses, and cremations are only know from two sites (Marmes, where at least ten where found with six of them inside a hearth, and Spirit Cave where two cremations were put into woven bags and buried in a cave). A comparison with Ushki L6 where two child inhumation burials underneath a hut floor were found in Layer 6 seemed more rewarding according to the authors. Although I personally see more similarities to e.g.  Marmes where several skeleton were burnt together with a great amount of animal bones (mostly small mammals and salmon, too) in a pit-hearth. Also the date for Marmes (10,500 years BP) is as close to USRS as Ushki’s are (10,350 years BP).

What I personally didn’t like about the essay was the rash interpretations of the authors. From the start they referred to the human remains and the construction as ‘the burial and house’, thus generating the idea of an actual ‘burial’ in a domestic context. Can we really infer this from the data given by the authors?

Less than 20 % of the child’s skeleton was present. The listing of the missing parts roused some conspiciousness. “Most vertebral centra and arches, the scapulae, clavicles, innominates, and almost all bones of the legs and feet are absent”. However, the remaining fragile bones, and we are talking of pieces up to 2 cm, were lying in situ. Someone must have removed very carefully the missing 80 % of the bones  of the burnt skeleton. The cremation in the pit-hearth could therefore very well addressed as pre-burial preparation, the ‘important’ bones being removed and the the actual burial could have taken place elsewhere, leaving the feature as an excarnation place. A separate excarnation in contrast to the actual burial would also very well explain the absence of ‘grave goods’.

The statement that the faunal remains belonged to “earlier episodes” is in my opinion questionable, since the dates all fall into the same age range. Other possible explanations are a funerary feast or ritual burning (after all we are talking about 213 -a third of all present species- voles and mice which were burnt complete in contrast to the squirrel stew) or anything in between. Strangely no radiocarbon dates were taken from faunal remains.

Stone tools are more more or less restricted to one side of the building, which according to the position of the postholes  might have been the back of the building, and consisted of flakes from tool maintenance. With hardly any other flakes or microblades this could be connected to a single event, namely the erecting of the building, specially built for the cremation/excarnation event. No domestic refuge seems to be existing that would support earlier domestic occupation.

The presented plan of the building shows a considerable charcoal staining around the building but is not addressed in the text at all.

Despite the suggestive and somewhat pre-occupied interpretation of the authors, this is a very exciting discovery and the excellent geoarchaeological  work and the detailed examination of the faunal and human remains will add immensely to our understanding of the peopling of North America and especially about ritual behaviour and treatment of the dead within these early settler communities in America.

Full citation of article: BA Potter et al., A Terminal Pleistocene Child Cremation and Residential Structure from Eastern Beringia, Science 331, 2011, 1058-62.

Petrie Museum, London

The Petrie Museum is with roughly 80,000 artefacts one of the finest museums on Egyptian and Sudanese archaeology. The initial collection was donated by the writer Amelia Edwards. Together with Sir William Flinders Petrie’s private collection, which he sold to the University College in 1913 it soon became one of the leading collections of Egyptian art outside of Egypt.

Hopefully they will move into a new building soon where the richness of their collection can be more appreciated than at their current home in the Darwin Building on the UCL campus.

Meanwhile enjoy a collection of memories from this year’s visit  here at my blog 🙂

Mit seinen über 80.ooo Sammlungsstücken ist das Petrie Museum in London eines der bedeutendsten Museen für ägyptische und sudanesische Archäologie außerhalb Ägyptens. Die ersten Stücke wurden von der Schriftstellerin Amelia Edwards an das University College in London gestiftet. 1913 hat dann Sir William Flinders Petrie seine umfangreiche Privatsammlung an das College verkauft. Zuerst nur für Forscher und zur Ausbildung von akademischen Nachwuchs gedacht ist das Museum heute öffentlich zugänglich. Es befindet sich nach wie vor auf dem Gelände des University Colleges (UCL) im sogenannten Darwin Building in Bloomsberry.

Ein größeres Museum ist in Planung, wird aber noch sicher dieses Jahr dauern. Dann jedenfalls wird die Sammlung über drei Stockwerke ausgestellt und kann so besser gewürdigt werden als in den bisherigen 2 Räumen und ein Treppenhaus 🙂

Wer sich bis dahin schon mal ein Bild der Objekte dort machen will kann auf meinem Blog nachschauen. Ich habe dort einige Erinnerungen von meinem diesjährigen Besuch im Petrie Museum online gestellt.