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02/16/2022 14:44

The green pyramids of Palau - Geo-archaeological research project on the island of Babeldaob, Micronesia

Eva Sittig Presse, Kommunikation und Marketing
Christian-Albrechts-Universität zu Kiel

    According to oral tradition, a huge serpent wound around the hills on the Palauan island and created the terraces with her body. But how did the monumental earthworks on Babeldaob really come about? Researchers from the Institute for Ecosystem Research at Kiel University (CAU), in collaboration with the Commission for the Archaeology of Non-European Cultures (KAAK) of the German Archaeological Institute (DAI), have now discovered a worldly explanation: the earth formations were created by hand over generations. They were used to grow food for the population, but also as burial sites.

    During the excavation, the research team worked closely with the residents of Palau and received broad support.

    Work for generations

    Monumental buildings from prehistoric times are widespread in Oceania, including the well-known stone figures and ceremonial platforms on Easter Island. The early cultures of Oceania often significantly transformed the landscapes of the islands. Around 500 BC, this development may have commenced in Palau. "The effort involved in the creation of the earthworks there is certainly comparable with the pyramids in Egypt or South America," said Dr Andreas Mieth, who is one of the three project leaders. "Over many generations, and with an almost unimaginable amount of work, millions of tons of soil must have been moved by workers. An achievement that could only be possible in a politically well-organised society," explained Dr Annette Kühlem, research coordinator and excavation leader. "Presumably the builders had hardly any tools available for the work. And even if they did, they were made of stone or organic material." Using geo-archaeological methods, the interdisciplinary team of soil scientists, paleoecologists and archaeologists have unravelled the mystery of the construction of the terraces. As a basis, the builders used weathered volcanic rock, interspersed with large quantities of ceramics. In contrast, the upper layers consist of carefully applied humus soils. Evidence of planting pits in the humus layers suggests extensive horticulture on the terraces. There are no indications of erosion. "So this was also technically very sustainable work," stated Professor Hans-Rudolf Bork, project leader.

    But the summits on some earthworks, which are up to ten meters high and visible from a distance, and which were also largely built by human hands, had a completely different function to the terraces, which were mainly used for horticulture. At one of the summits in the south of Babeldaob, the scientists and their local helpers were able to uncover six skeletons within a complex burial site. "This is a sensational find and to date unique for the earthworks of Palau. Such well-preserved burials have never been discovered there because bones usually decompose very quickly in the acidic soils," said Dr Annette Kühlem. Perhaps mineral additives may have slowed down such decomposition here – one of the theses that should now be pursued using laboratory analyses.

    New findings for research and the population

    The discovery has great scientific potential for the experts. For the first time, they are able to document the details of a prehistoric burial on Babeldaob and compare it with today's traditional burial practices. "Due to the fairly well-preserved skulls, there is still hope of being able to carry out DNA analyses and thus relationship analyses, perhaps even in comparison with the population living in the area today. This may potentially also close a gap in tracing the settlement of Oceania," explained Dr Annette Kühlem. The project participants suspect that only members of the elite were buried on the intricately laid and shaped summits of the earthworks. Thus, even after their death, their social status was made clear in a prominent way, visible from afar.

    The new findings have elicited an extraordinarily positive response in the island state of Palau. The research into the terraced earthworks enabled the local people to gain a new perspective of their own culture. Political as well as traditional officials and dignitaries, but also school classes and the Palauan press, have taken the path up the steep summit of the earthworks to visit the site. The discovery was the subject of a headline on the front page and an extensive report in the Island Times. All those involved then celebrated the conclusion of the fieldwork in December 2021 in a very special way. The six deceased from the summit of Ngerbuns el Bad were reburied in a ceremony with traditional chants by the women of the highest clan of the associated village. For burial, the skeletons were covered with woven mats made of pandanus fibres. An areca nut (betel nut) wrapped in leaves was placed with each of the deceased before the mat was covered with soil. In this way, respects were paid to the dead once again after hundreds of years.

    The project was funded by the German Research Foundation (DFG 421517148).
    Research coordinator and excavation leader:
    Dr Annette Kühlem (CAU)

    Project leaders:
    Prof. Dr Hans-Rudolf Bork (CAU)
    Dr Andreas Mieth (CAU)
    Dr Burkard Vogt (DAI)

    Photos are available for download at:
    Aerial view of the Ngerbuns el Bad earthworks on the Palauan island of Babeldaob.
    © C. Hartl-Reiter
    Aerial view of the uncovered burial site at the summit of the Ngerbuns el Bad earthworks.
    © C. Hartl-Reiter
    Archaeological excavation at the summit of the Ngerbuns el Bad earthworks.
    © C. Hartl-Reiter
    The excavation team at the summit.
    © M. Moore
    The dead uncovered during the excavation were reburied by women of the associated clan according to traditional rites.
    © M. Moore
    Excavation leader Annette Kühlem explains the archaeological works and findings to a school group on site.
    © C. Hartl-Reiter

    Dr Annette Kühlem
    Institute for Ecosystem Research

    Kiel University
    Press, Communication and Marketing, Eva Sittig, Text/editing: Christin Beeck
    Postal address: D-24098 Kiel, Germany, Telephone: +49 431 880-2104, Fax: +49 431 880-1355
    E-mail:, Internet: Twitter:
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    Contact for scientific information:

    Dr Annette Kühlem
    Institute for Ecosystem Research

    More information:


    Criteria of this press release:
    Journalists, Scientists and scholars
    Cultural sciences, Geosciences, History / archaeology
    transregional, national
    Research results



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