New fossil evidence claims first discovery of taro in Māori gardens

By: Thomas Schmitt Attorney on April 09, 2019 / comment : 0 Archaeology, New Zealand, Oceania, Polynesia

The first discovery of Polynesian taro grown in Māori gardens in the 1400s can be claimed by an archaeological research project on Ahuahu-Great Mercury Island.

Photomicrographs of the invertebrate fossil taxa. B, A1 (head, EA204, 210 cm to 220 cm, early garden), B, A2 (head, RAIDA4, 90 cm to 95 cm, late garden), B, A3 (elytron, EA204, 210 cm to 220 cm, early garden), B, A4 (thorax, EA204, 210 cm to 220 cm, early garden), and B, A5 (prothorax, EA204, 210 cm to 220 cm, early garden) are C. desjardinsi; B, B (forceps, TUKOU2, 58 cm to 60 cm, late garden) is E. annulipes; B, C1 and C2 (elytra, EA204, 170 cm to 180 cm, late garden) are Ataenius cf. picinus; B, D1 and D2 (heads, EA204, 170 cm to 180 cm, late garden) are Aleocharinae spp.;  B, E1 (head, EA204, 190 cm to 200 cm, early garden) and B, E2 (pronotum, EA204, 190 cm to 200 cm, early garden) are Carpelimus sp.; B, F1 (elytron, EA204, 80 cm to 90 cm, PEC) is Dactylosternum cf. marginale; B, F2 (elytron, RAIDA4, 100 cm to 105 cm, late garden) is D. abdominale; B, G1 (elytron, EA204, 190 cm to 200 cm, early garden) is Saprosites sp.; B, G2 (elytron, RAIDA4, 50 cm to 55 cm, PEC) is S, pygmaeus; B, H (head, TUKOU2, 74 cm to 76 cm, late garden) is Tetramorium pacificum (Formicidae); B, I (head, EA204, 90 cm to 100 cm PEC) is Hypoponera cf. punctatissima (Formicidae); and B, J (head, RAIDA4, 95 cm to 100 cm, late garden) is Nylanderia sp. (Formicidae). (Scale bar, 0.5 mm.) [Credit: Nicholas Porch and Matthew Prebble]

Jointly carried out by the University of Auckland and Auckland War Memorial Museum, the project's new evidence displays the sophistication with which early Māori first utilised the New Zealand environment, and also that they developed wetland gardens for taro.

Previous archaeological evidence favoured kumara as the only viable crop in New Zealand's cooler climates but this new research, which explored the history of Māori settlement on the island, indicates taro was also an important crop in the early Māori diet, alongside leafy greens such as pūhā and watercress.

During extensive field work on the private island off the eastern coast of Coromandel, palynologist Matthew Prebble of the Australian National University, alongside a team of archaeologists from the University of Auckland and Auckland War Memorial Museum, analysed buried sediments from swamps which contained the pollen of taro and other leafy greens.

The deposits have been radiocarbon-dated to the 14th century, around 600 to 700 years ago. Along with the taro and kumara, some of the green leafy plants were probably introduced by Tūpuna Māori, and the gardens on Ahuahu are among some of the earliest known of in New Zealand.

This is a map of the South Pacific Ocean showing the southern Polynesian islands (brown dashed line) examined in this study (blue boxes). Insets A-C show the study islands, including sediment core locations  and high elevation points [Credit: Matthew Prebble]

Team member, the University of Auckland's Professor Simon Holdaway, says archaeologists have long considered the cooler climate of New Zealand, compared to the warmer climate of Polynesian islands, hindered early attempts Māori's early attempts to grow traditional Polynesian crops such as taro.

"This evidence for early taro production refutes the long-held view that only kumara could be grown in New Zealand," he says.

"It indicates Tūpuna Māori may have initially focused on taro and created specialised wetland gardens for the purpose; kumara then became the main crop after AD 1500."

Pre-European Māori gardens were also thought to have been relatively weed free, but the fossil pollen remains from Ahuahu suggest indigenous edible leafy herbs such as watercress and pūhā were common. The early Māori diet was balanced by a range of vegetables.

He Waitetoke Mire on Ahuahu-Great Mercury Island where the team found the taro and puha pollen [Credit: Matthew Prebble]

Based on this information, it's now thought that Ahuahu was used by Tūpuna Māori to grow gardens because of the limited amount of kauri and rimu forests which were difficult to clear with fire, the limited exposure to frosts and the similarity of the island to the Polynesian homeland islands.

Matthew Prebble has also analysed swamp cores from islands in southern French Polynesia, in Raivavae and Rapa, which showed many of the same weeds also lived in early taro gardens in the subtropics and tropics.

The new evidence suggests that Polynesians gardeners were inventive and adapted the environment to continue growing their staple food, taro.

A paper on this ground-breaking research, authored by Matthew Prebble, was published in the Proceedings of the National Academy of Sciences.

Author: Julianne Evans | Source: University of Auckland [April 09, 2019]

Hats on for Easter Island statues

By: Thomas Schmitt Attorney on June 04, 2018 / comment : 0 Archaeology, Easter Island, Polynesia, South America

How do you put a 13-ton hat on a giant statue? That's what a team of researchers is trying to figure out with their study of Easter Island statues and the red hats that sit atop some of them.

Restored statue platform with standing moai on the south coast of Rapa Nui. Note that one of the moai is adorned with a red scoria pukao [Credit: Sean Hixon]

"Lots of people have come up with ideas, but we are the first to come up with an idea that uses archaeological evidence," said Sean W. Hixon, graduate student in anthropology, Penn State.

Rapa Nui - Easter Island, Chile - sits in the Southern Pacific Ocean more than 2,000 miles from Chile in South America. The island is about 15 miles long and 7.6 miles wide at its widest with an area of about 63 square miles. According to the researchers, the island was first inhabited in the 13th century by Polynesian travelers.

The statues, carved from volcanic tuff, came from one quarry on the island, while the hats, made of red scoria, came from a different quarry 7.5 miles away on the other side of the island.

Previous research by Carl P. Lipo, professor of anthropology, Binghamton University, and Terry Hunt, professor of anthropology and dean of the Honors College, University of Arizona, determined that the statues, which can be up to 33 feet tall and weigh 81 tons, were moved into place along well-prepared roads using a walking/rocking motion, similar to the way a refrigerator is moved.

"The statues were moved in a fashion using simple physics-based processes in a way that was elegant and remarkably effective," said Lipo. Not all statues made it to their final locations, and the fallen and/or broken ones showed that, to move them, the statues were carved so they leaned forward and were later leveled off for final placement.

The hats, with diameters up to 6.5 feet and weighing 13 tons, might have been rolled across the island, but once they arrived at their intended statues, they still needed to be lifted onto the statues' heads. The islanders probably carved the hats cylindrically and rolled them to the statues before further carving the hats to attain the final shapes, which vary from cylindrical to conical and which usually have a smaller cylindrical projection on the top. Chips of red scoria are found in the platform of some of the statue hat combinations.

"We were interested in figuring out the method of hat transport and placement of the hats that best agrees with the archaeological record," said Hixon.

Diagram of pukao emplacement scenario that is supported by analysis of pukao form and the physics associated with pukao transport [Credit: Sean Hixon]

The researchers took multiple photographs of many Rapa Nui hats to see what attributes of the hats were the same throughout. Using photogrammetry and 3-D imaging, they created images of the hats with all their details.

"We assumed they were all transported and placed in the same way," said Hixon. "So we looked for features that were the same on all the hats and all the statues."

The only features they found the same were indentations at the bases of the hats, and these indentations fit the tops of the statues' heads. If the hats had been slid in place on top of the statues, then the soft stone ridges on the margin of the indentations would have been destroyed. So the islanders must have used some other method.

Previous researchers suggested that the statues and the hats were united before they were lifted in place, but the remnants of broken or abandoned statues, and other evidence for walking the statues, indicates this was not the approach used and that the hats were most likely raised to the top of standing statues. Many of the hats left around the island are much larger than those placed on statues.

"The best explanation for the transport of the pukao (hats) from the quarry is by rolling the raw material to the location of the moai (statues)," said Lipo. "Once at the moai, the pukao were rolled up large ramps to the top of a standing statue using a parbuckling technique." Parbuckling is a simple and efficient technique for rolling objects and is often used to right ships that have capsized. The center of a long rope is fixed to the top of a ramp and the two trailing ends are wrapped around the cylinder to be moved. The rope ends are then brought to the top where workers pull on the ropes to move the cylinder up the ramp.

Rano Raraku Statue Quarry and Puna Pau Pukao Quarry" Location of red scoria pukao quarry at Puna Pau (green square) and moai quarry at Rano Raraku (black square). Green circles mark locations of pukao [Credit: Sean Hixon]

Besides reducing the force needed to move the hats, this arrangement also makes it easier to stabilize the hat on the trip up because the hat typically will not roll back down the slope. The researchers report in the current issue of the Journal of Archaeological Science, that 15 or fewer workers could move the largest preform hats up the ramps.

Once the hat was at the top of the ramp, it could not simply be pushed into place because of the ridges on the margin of the hat base indentation. Rather, the researchers believe that the hats were tipped up onto the statues.

First the hat would be modified to its final form, some including a second, smaller cylindrical piece on top.

The hats could be rotated 90 degrees and then levered up with small wooden levers to sit on the statue tops, or the ramp could be slightly to the side, so that rotation in the small space at the top of the ramp would be unnecessary. Then the hat would simply be levered and pivoted on edge and into place.

The ramps were then disassembled and became the wings of the platform surrounding the statues.

"This is the first time anyone has systematically explored the evidence for how the giant hats were placed on the top of the heads of the massive statues of Easter Island," said Lipo. "Our work combines cutting-edge 3-D modeling with artifact analysis and models drawn from physics to arrive at the best answer."

Source: Pennsylvania State University [June 04, 2018]

Pacific rats trace 2,000 years of human impact on island ecosystems

By: Thomas Schmitt Attorney on June 04, 2018 / comment : 0 Archaeology, Ecosystems, Oceania, Palaeoclimate, Polynesia

Chemical analysis of the remains of rats from archaeological sites spanning the last 2000 years on three Polynesian island systems has shown the impact that humans have had on local environments. The analysis by an international team of scientists allowed the researchers to reconstruct the rats' diets - and through them the changes made by humans to local ecosystems, including native species extinctions and changes to food webs and soil nutrients.

Excavation of 'Kitchen Cave' Rockshelter (KAM-1) in progress. Kamaka Island, Gambier Archipelago (Mangareva) [Credit: Patrick V. Kirch]

The Earth has arguably entered a new geological epoch called the Anthropocene, an era in which humans are bringing about significant, lasting change to the planet. While most geologists and ecologists place the origins of this era in the last 50 to 300 years, many archaeologists have argued that far-reaching human impacts on geology, biodiversity, and climate extend back millennia into the past.

Ancient human impacts are often difficult to identify and measure compared to those happening today or in recent history. A new study published in the Proceedings of the National Academy of Sciences by researchers at the Max Planck Institute for the Science of Human History in Jena and the University of California, Berkeley advances a new method for detecting and quantifying human transformations of local ecosystems in the past. Using state of the art methods, researchers searched for clues about past human modifications of island ecosystems from an unusual source - the bones of long-dead rats recovered from archaeological sites.

One of the most ambitious and widespread migrations in human history began c. 3000 years ago, as people began voyaging across the Pacific Ocean--beyond the visible horizon--in search of new islands. By around 1000 years ago, people had reached even the most remote shores in the Pacific, including the boundaries of the Polynesian region: the islands of Hawai'i, Rapa Nui (Easter Island) and Aotearoa (New Zealand). Not knowing what they would encounter in these new lands, early voyagers brought with them a range of familiar plants and animals, including crops such as taro, breadfruit, and yams, and animals including the pig, dog, and chicken. Amongst the new arrivals was also the Pacific rat (Rattus exulans), which was carried to almost every Polynesian island on these early voyages, perhaps intentionally as food, or equally likely, as a hidden "stowaway" aboard long-distance voyaging canoes.

Agakauitai Island in the Gambier Archipelago (Mangareva) [Credit: Jillian A. Swift]

The arrival of the rat had profound impacts on island ecosystems. Pacific rats hunted local seabirds and ate the seeds of endemic tree species. Importantly, commensal animals like the Pacific rat occupy a unique position in human ecosystems. Like domestic animals, they spend most of their time in and around human settlements, surviving on food resources produced or accumulated by people. However, unlike their domestic counterparts, these commensal species are not directly managed by people. Their diets thus provide insights into the food available in human settlements as well as changes to island ecosystems more broadly.

But how to reconstruct the diet of ancient rats? To do this, the researchers examined the biochemical composition of rat bones recovered from archaeological sites across three Polynesian island systems. Carbon isotope analysis of proteins preserved in archaeological bone indicates the types of plants consumed, while nitrogen isotopes point to the position of the animal in a food web. Nitrogen isotopes are also sensitive to humidity, soil quality, and land use. This study examined the carbon and nitrogen isotopes of archaeological Pacific rat remains across seven islands in the Pacific, spanning roughly 2000 years of human occupation. The researchers' results demonstrate the impacts of processes like human forest clearance, hunting of native avifauna (in particular land birds and seabirds) and the development of new, agricultural landscapes on food webs and resource availability.

A near-universal pattern of changing rat bone nitrogen isotope values through time was linked to native species extinctions and changes in soil nutrient cycling after people arrived on the islands. In addition, significant changes in both carbon and nitrogen isotopes correspond with agricultural expansion, human site activity, and subsistence choices. "We have many strong lines of archaeological evidence for humans modifying past ecosystems as far back as the Late Pleistocene," says lead author Jillian Swift, of the Max Planck Institute for the Science of Human History. "The challenge is in finding datasets that can quantify these changes in ways that allow us to compare archaeological and modern datasets to help predict what impacts human modifications will have on ecosystems in the future."

Pacific rats (Rattus exulans) [Credit: Photo taken by John Stokes (Bernice P. Bishop Museum), and courtesy of Patrick V. Kirch]

Prof. Patrick V. Kirch of the University of California, Berkeley, who supervised the study and led excavations on Tikopia and Mangareva, remarked that "the new isotopic methods allow us to quantify the ways in which human actions have fundamentally changed island ecosystems. I hardly dreamed this might be possible back in the 1970s when I excavated the sites on Tikopia Island."

"Commensal species, such as the Pacific rat, are often forgotten about in archaeological assemblages. Although they are seen as less glamorous 'stowaways' when compared to domesticated animals, they offer an unparalleled opportunity to look at the new ecologies and landscapes created by our species as it expanded across the face of the planet," added Patrick Roberts of the Max Planck Institute for the Science of Human History, a co-author on the paper. "The development and use of stable isotope analysis of commensal species raises the possibility of tracking the process of human environment modification, not just in the Pacific, but around the world where they are found in association with human land use."

The study highlights the extraordinary degree to which people in the past were able to modify ecosystems. "Studies like this clearly highlight the human capacity for 'ecosystem engineering,'" notes Nicole Boivin, coauthor of the study and Director of the Department of Archaeology at the Max Planck Institute for the Science of Human History. "We clearly have long had the capability as a species of massively transforming the world around us. What's new today is our ability to understand, measure, and alleviate these impacts."

Source: Max Planck Institute for the Science of Human History [June 04, 2018]

Sweet potato history casts doubt on early contact between Polynesia and the Americas

By: Thomas Schmitt Attorney on April 13, 2018 / comment : 0 Americas, Evolution, Genetics, Polynesia

Evidence reported in the journal Current Biology shows that sweet potatoes arose before there were any humans around to eat them. The findings also suggest that the sweet potato crossed the ocean from America to Polynesia without any help from people. The discovery raises doubts about the existence of pre-Columbian contacts between Polynesia and the American continent.

This image shows detail of a flower of Ipomoea cordatotriloba, a close wild relative of sweet potato from South America [Credit: Pablo Munoz-Rodriguez]

"Apart from identifying its progenitor, we also discovered that sweet potato originated well before humans, at least 800,000 years ago," says Robert Scotland from the University of Oxford. "Therefore, it is likely that the edible root already existed when humans first found this plant."

Scotland and colleagues set out to clarify the origin and evolution of the sweet potato, which is one of the most widely consumed crops in the world and an important source of vitamin A precursors. They also aimed to explore a question that has been of interest for centuries: how did the sweet potato, a crop of American origin, come to be widespread in Polynesia by the time Europeans first arrived? In fact, researchers have suggested that the sweet potato's early presence in Polynesia was evidence of pre-European contacts between Americans and Polynesians.

The researchers combined genome skimming and target DNA capture to sequence the whole chloroplasts and 605 single-copy nuclear regions from 199 specimens representing the sweet potato and all of its crop wild relatives. The data strongly suggest that sweet potato arose after a genome duplication event. Its closest wild relative is Ipomoea trifida. The findings confirm that no other extant species was involved in the sweet potato's origin.

Phylogenetic analysis of the DNA sequences produced conflicting family trees. However, the researchers report, those conflicting patterns can be explained by a dual role for I. trifida. Sweet potato arose from I. trifida and later hybridized with I. trifida to produce another, independent sweet potato lineage.

"We demonstrate that the existence of those two different lineages is the result of an ancient hybridization between sweet potato and its progenitor," says Munoz-Rodriguez, first author of the paper. "We conclude that sweet potato evolved at least 800,000 years ago from its progenitor, and then after the two species became distinct, they hybridized."

The findings come as good news for the future of the sweet potato. That's because the loss of genetic diversity in crops is a major threat for food security. One way to improve or reinforce desirable properties in food crops is to cross them with their closest wild relatives. So, Scotland says, the identification of the sweet potato's progenitor opens the door to a more accurate understanding of its potential role in sweet potato breeding.

The new view on sweet potato history also has major implications for understanding human history.

"Our results challenge not only the hypothesis that the sweet potato was taken to Polynesia by humans, but also the long-time argued existence of ancient contacts between Americans and Polynesians," Munoz-Rodriguez says. "These contacts were considered as true based on evidence from chickens, humans, and sweet potato. Evidence from chickens and humans is now considered questionable, and thus sweet potato was the remaining biological evidence of these alleged contacts. Therefore, our results refute the dominant theory and call into question the existence of pre-European contacts across the Pacific."

Author: Cell Press [April 13, 2018]