Semi-supervised machine learning approaches for predicting the chronology of archaeological sites: A case study of temples from medieval Angkor, Cambodia

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via PLOS One, 5 Nov 2018: A cool new Open Access paper by Klassen et al. using machine learning to create a predictive chronology of Angkorian temples based on the architectural features and artifacts found at a site.

Source: buffaloboy / Shutterstock

Source: buffaloboy / Shutterstock

Archaeologists often need to date and group artifact types to discern typologies, chronologies, and classifications. For over a century, statisticians have been using classification and clustering techniques to infer patterns in data that can be defined by algorithms. In the case of archaeology, linear regression algorithms are often used to chronologically date features and sites, and pattern recognition is used to develop typologies and classifications. However, archaeological data is often expensive to collect, and analyses are often limited by poor sample sizes and datasets. Here we show that recent advances in computation allow archaeologists to use machine learning based on much of the same statistical theory to address more complex problems using increased computing power and larger and incomplete datasets. This paper approaches the problem of predicting the chronology of archaeological sites through a case study of medieval temples in Angkor, Cambodia. For this study, we have a large dataset of temples with known architectural elements and artifacts; however, less than ten percent of the sample of temples have known dates, and much of the attribute data is incomplete. Our results suggest that the algorithms can predict dates for temples from 821–1150 CE with a 49-66-year average absolute error. We find that this method surpasses traditional supervised and unsupervised statistical approaches for under-specified portions of the dataset and is a promising new method for anthropological inquiry.

Source: Semi-supervised machine learning approaches for predicting the chronology of archaeological sites: A case study of temples from medieval Angkor, Cambodia

How did the first humans migrate into Australia?

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via various sources including ANU Media, the Guardian and the Journal of Human Evolution: A new paper in the Journal of Human Evolution models the “least-cost pathways” humans would have taken through Island Southeast Asia in order to reach Australia, offering a predictive insight into areas of high archaeological potential.

Least-cost pathway models indicate northern human dispersal from Sunda to Sahul
Kealy et al., https://doi.org/10.1016/j.jhevol.2018.10.003

Archaeological records from Australia provide the earliest, indirect evidence for maritime crossings by early modern humans, as the islands to the north-west of the continent (Wallacea) have never been connected to the mainland. Suggested in 1977 by Joseph B. Birdsell, the two main routes from Sunda (mainland Southeast Asia) to Sahul (Australia-New Guinea), still in debate today, are a northern route through Sulawesi with a landing in New Guinea, or a southern route through Bali, Timor and thence landing in northern Australia. Here we construct least-cost pathway models of human dispersal from Sunda to Sahul at 65 ka and 70 ka by extending previous out-of-Africa least-cost models through the digitization of these routes. We recover overwhelming support for a northern route into Sahul, with a landing location on present-day Misool Island. Minimal support is also recovered for the southern route at 70 ka, with a possible crossing to Sahul from eastern Timor. Review of archaeological records on the Wallacean islands crossed by our northern route indicate a dearth of archaeological research in this region. Meanwhile, the comparatively better studied southern islands still lack any archaeological dates comparable to those known for initial occupation in Sunda and Sahul. Based on our model results we suggest Misool Island as the initial landing site for early modern humans on Sahul and recommend a future focus on archaeological fieldwork in the northern Wallacean islands.

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When Thailand and Australia were closer neighbours, tectonically speaking

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via The Conversation, 20181019

via the Conversation, 19 October 2018: The geological periods when parts of Thailand and Australia were part of the same land mass go very far back in time, even before the dinosaurs, but an interesting read about the ancient history of our rocks.

This was a time before the dinosaurs, when the first forests turned the land green and giant dragonflies tracked airways through the vegetation.

Our work suggests that some fictional time-travelling Phuket beach-lover could have walked to the Pilbara in Western Australia. A pre-Jurassic culture vulture in Ayutthaya could have trekked over an ancient Indonesian-like volcanic island chain, and some Khao Yai elephant-ancestor could have rampaged through the site of the Perth CBD.

Source: When Thailand and Australia were closer neighbours, tectonically speaking

[Paper] The demise of Angkor: Systemic vulnerability of urban infrastructure to climatic variations

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A new paper in Science Advances by Penny et al. suggests that climatic fluctuations which stressed Angkor’s urban hydraulic system may have ultimately contributed to the city’s ‘demise’. The conclusions were reached from computer simulations modelling the effect of monsoon rains and droughts onto Angkor’s urban infrastructure.

Complex infrastructural networks provide critical services to cities but can be vulnerable to external stresses, including climatic variability. This vulnerability has also challenged past urban settlements, but its role in cases of historic urban demise has not been precisely documented. We transform archeological data from the medieval Cambodian city of Angkor into a numerical model that allows us to quantify topological damage to critical urban infrastructure resulting from climatic variability. Our model reveals unstable behavior in which extensive and cascading damage to infrastructure occurs in response to flooding within Angkor’s urban water management system. The likelihood and extent of the cascading failure abruptly grow with the magnitude of flooding relative to normal flows in the system. Our results support the hypothesis that systemic infrastructural vulnerability, coupled with abrupt climatic variation, contributed to the demise of the city. The factors behind Angkor’s demise are analogous to challenges faced by modern urban communities struggling with complex critical infrastructure.

Source: The demise of Angkor: Systemic vulnerability of urban infrastructure to climatic variations | Science Advances

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City of Koh Ker was occupied for centuries longer than previously thought

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via PhysOrg, 10 October 2018: A new Open Access paper in PLOS One indicates that the ‘brief’ 10th century Khmer capital of Koh Ker may not have been so brief after all.

Source: Tegan et al., PLOS ONE. https://doi.org/10.1371/journal.pone.0203962

Source: Tegan et al., PLOS ONE. https://doi.org/10.1371/journal.pone.0203962

The classic account of the ancient city of Koh Ker is one of a briefly-occupied and abruptly-abandoned region, but in reality, the area may have been occupied for several centuries beyond what is traditionally acknowledged, according to a study published October 10, 2018 in the open-access journal PLOS ONE by Tegan Hall of the University of Sydney, Australia and colleagues.

Koh Ker was part of the Khmer kingdom during the Angkor period in what is now Cambodia. For a mere two decades in the tenth century CE, the city served as royal capital, and it has long been proposed that after the royal seat moved back to Angkor, the city and its surroundings were abandoned. In this study, Hall and colleagues tested this theory by analyzing charcoal and pollen remains in sediment cores spanning several centuries in three Koh Ker localities, including the moat of the main central temple. From these data, they inferred a long history of fluctuations in fire regimes and vegetation which are highly indicative of patterns of human occupation and land use over time.

Source: City of Koh Ker was occupied for centuries longer than previously thought

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Re-evaluating the occupation history of Koh Ker, Cambodia, during the Angkor period: A palaeo-ecological approach | PLOS One

Categories: Angkor Cambodia Papers

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Urbanism and Residential Patterning in Angkor

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New paper by Carter et al. in the Journal of Field Archaeology

The Khmer Empire (9th–15th centuries a.d.), centered on the Greater Angkor region, was the most extensive political entity in the history of mainland Southeast Asia. Stone temples constructed by Angkorian kings and elites were widely assumed to have been loci of ritual as well as habitation, though the latter has been poorly documented archaeologically. In this paper, we present the results of two field seasons of excavation at the temple site of Ta Prohm. Using LiDAR data to focus our excavations, we offer evidence for residential occupation within the temple enclosure from before the 11th century a.d. until the 14th century. A comparison with previous work exploring habitation areas within the Angkor Wat temple enclosure highlights similarities and differences between the two temples. We argue that temple habitation was a key component of the Angkorian urban system and that investigating this unique form of urbanism expands current comparative research on the diversity of ancient cities.

Source: Urbanism and Residential Patterning in Angkor: Journal of Field Archaeology: Vol 43, No 6

Indonesian archaeology research archive

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Highlighting a new and very significant web resource, the Indonesian Ministry of Education and Culture’s Repository of research. The link below is the search result for all things related to archaeology deposited in the Institute’s Repository – about 400 items! This is a great initiative, and I wish more countries and institutions would do the same.

Source: Search results for arkeologi – Repositori Institusi Perpustakaan Kemendikbud

Southeast Asian population boomed 4,000 years ago

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Clare McFadden, lead author. Source: ANU

via Science Daily/ANU, 20 September 2018: A new paper in the Journal of Archaeological Science shows evidence for a rapid population growth in Southeast Asia around 4,000 years ago using an analysis that takes into account the proportion of children and infants in population measurements.

Clare McFadden, lead author. Source: ANU

Clare McFadden, lead author. Source: ANU

Researchers at The Australian National University (ANU) have uncovered a previously unconfirmed population boom across South East Asia that occurred 4,000 years ago, thanks to a new method for measuring prehistoric population growth.

Using the new population measurement method, which utilises human skeletal remains, they have been able to prove a significant rapid increase in growth across populations in Thailand, China and Vietnam during the Neolithic Period, and a second subsequent rise in the Iron Age.

Source: Southeast Asian population boomed 4,000 years ago — ScienceDaily

[Paper] Portable X-ray fluorescence analysis of ceramic covered boxes from the 12th/13th-century Java Sea Shipwreck

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via Journal of Archaeological Science Reports: Portable XRF analysis of Qingbai from the Java Sea Shipwreck.

Forty-one ceramic boxes from the twelfth- or thirteenth-century Java Sea Shipwreck were analyzed at the Elemental Analysis Facility at Chicago’s Field Museum using nondestructive portable x-ray fluorescence (PXRF). Twenty-two samples have a qingbai-type glaze and nineteen are painted ware with painted black decorations originally covered by a lead-based green glaze. The goals of the analysis were to (1) test whether visually similar ceramics shared similar elemental compositions; (2) identify ceramics that might have been made at different kiln sites (or from different paste recipes); and (3) determine if compositional groups in the ceramic dataset differentiated using PXRF are archaeologically meaningful. Based on this study, although PXRF can be successfully used to some degree to differentiate between different groups of qingbai-type ceramics, more research needs to be done on its applicability to painted ware pastes.

Source: Portable X-ray fluorescence analysis of ceramic covered boxes from the 12th/13th-century Java Sea Shipwreck: A preliminary investigation – ScienceDirect

[Paper] The spatio-temporal distribution of archaeological and faunal finds at Liang Bua (Flores, Indonesia) in light of the revised chronology for Homo floresiensis

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New Open Access paper in the Journal of Human Evolution examines the distribution stone artefacts and faunal remains of Liang Bua over 190,000 years. Changes in the assemblage suggest that modern humans arrived to Liang Bua around 46,000 years ago.

Liang Bua, the type site of Homo floresiensis, is a limestone cave on the Indonesian island of Flores with sedimentary deposits currently known to range in age from about 190 thousand years (ka) ago to the present. Recent revision of the stratigraphy and chronology of this depositional sequence suggests that skeletal remains of H. floresiensis are between ∼100 and 60 ka old, while cultural evidence of this taxon occurs until ∼50 ka ago. Here we examine the compositions of the faunal communities and stone artifacts, by broad taxonomic groups and raw materials, throughout the ∼190 ka time interval preserved in the sequence. Major shifts are observed in both the faunal and stone artifact assemblages that reflect marked changes in paleoecology and hominin behavior, respectively. Our results suggest that H. floresiensis and Stegodon florensis insularis, along with giant marabou stork (Leptoptilos robustus) and vulture (Trigonoceps sp.), were likely extinct by ∼50 ka ago. Moreover, an abrupt and statistically significant shift in raw material preference due to an increased use of chert occurs ∼46 thousand calibrated radiocarbon (14C) years before present (ka cal. BP), a pattern that continues through the subsequent stratigraphic sequence. If an increased preference for chert does, in fact, characterize Homo sapiens assemblages at Liang Bua, as previous studies have suggested (e.g., Moore et al., 2009), then the shift observed here suggests that modern humans arrived on Flores by ∼46 ka cal. BP, which would be the earliest cultural evidence of modern humans in Indonesia.

Source: The spatio-temporal distribution of archaeological and faunal finds at Liang Bua (Flores, Indonesia) in light of the revised chronology for Homo floresiensis – ScienceDirect