Scanning life histories of stone age oysters

Lay summary authored by Niklas Hausmann. Read the full paper here:

Oysters are some of the most commonly eaten marine molluscs in the world.
This is true today and has been true for thousands of years.
During their history as reliable food source, oyster populations had ups and downs, and in Europe there were times when Oysters were eaten in the billions each year (Londoners alone ate 700 million per year in 1864), with dramatic effects on their overall number and life expectancy.

The European Oyster has not recovered from these times at all and currently, researchers as well as industrial fisheries are trying to build up sustainable population sizes again.
The problem with this large-scale endeavour is that we currently have only limited knowledge what such a population would look like in terms of its demography, life expectancy, or individual growth.
And to solve this problem, researchers are looking at archaeological sites from the Stone Age and during periods before any large-scale oyster exploitation. By looking at the ages, sizes and growth rates of these archaeological oysters, we can get a baseline, or reference, to which modern populations can be compared to.

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Elemental map and growth micro-image of the oyster shell thin section. The scale shown for the elemental map is also applicable to the mico-images. Note that the colouring of the elemental maps is based on the individual limits of each specimen’s Mg/Ca ratio, with bright colours showing high ratios and dark colours showing low ratios. Credit: N. Hausmann.

Our article, presents a new way of determining archaeological oyster ages in a very quick and inexpensive way, so that we can access this information in many places around Europe and throughout time.
Our new method is called elemental mapping through Laser Induced Breakdown Spectroscopy (LIBS), which is measuring geochemical changes in the different growth lines of the mollusc shell. The geochemical composition of those segments change depending on the environment and the animal specific internal processes. For instance, in the oysters, we expect the concentration of Magnesium to increase with higher growth rates. With most Northern European oysters stopping their growth during winter, we can use these repeating increases (and decreases) to reconstruct how many winters the animal lived through (i.e. their age in years).

Getting this kind of information is usually done via microscopic analysis of very thin slices of shell, which take a lot of time to make, or through other geochemical analyses using oxygen isotopes, which cost a lot of money.
So with our pilot study, we successfully explored the use of LIBS as a new, fast, and cost-effective way of looking at shells in the past, setting the way for regulating our current efforts of repopulating the overfished oyster regions of the North Sea.

Full paper: Hausmann, N., Robson, H.K. and Hunt, C., 2019. Annual Growth Patterns and Interspecimen Variability in Mg/Ca Records of Archaeological Ostrea edulis (European Oyster) from the Late Mesolithic Site of Conors Island. Open Quaternary, 5(1), p.9. DOI: http://doi.org/10.5334/oq.59
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Geoarchaeological Evidence for the Decline of the Medieval City of Qalhat, Oman

Lay summary authored by Gösta Hoffmann. Read the full paper here: https://www.openquaternary.com/articles/10.5334/oq.56/

Today the ruins of the Qalhat are a UNESCO world heritage site. In medieval times, the ancient city of Qalhat was an important trade town along the shores of the Indian Ocean. The reasons for the decline of the city are unknown but speculations include warfare as well as earthquake activity. The research concentrated on the coastline in the vicinity of Qalhat. The morphology of the coast indicates that the earth surface must have moved upwards in recent times. This can clearly be seen by a staircase of raised marine terraces. Uplifted beaches indicate rather young movement. Evidence is presented that these vertical movements are associated with earthquakes. The paper concludes that the decline of the ancient city of Qalhat is likely related to earthquake activity. This is of relevance as a modern gas liquefaction plant is located along the fault which is the most likely candidate to be responsible for the rupture some 500 years ago.

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Example of karstification. The Bimmah sinkhole. (A) location of the sinkhole (dot in the centre) as depicted in the digital elevation model. (B) and (C) the stratigraphy exposed in the sinkhole shows Eocene limestone, overlain by deltaic Pleistocene deposits. Figure taken from the original paper.

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Sowing the seeds of future research: Data sharing, citation and reuse in archaeobotany

Lay summary authored by Lisa Lodwick. The full article can be read in Open Quaternary: http://doi.org/10.5334/oq.62

Archaeobotanists spend countless hours at the microscope, sorting and identifying ancient plant remains. Counting seeds is a key step in the research process, enabling patterns to be established across sites, within regions, and through time – patterns that can tell us about a wide range of past human-plant relationships. As the number of archaeobotanical data sets have grown and statistical analysis has become more widely used, meta-studies have provided new insights into the timing of crop domestication, the spread of domesticated plants, and shifts in how crops were cultivated. Undertaking such meta-analysis relies on access to the counts of plant remains from the initial studies. However, there is a common perception that much data produced within archaeology, and across many academic disciplines, is not always made publicly available. How much seed count data is still available?

In this study, I used over 200 journal articles published over the last decade in 16 journals to assess how archaeobotanists are currently sharing their data. Whilst 56% of papers did provide their full or ‘raw’ data, this was often in forms that make the reuse of this data challenging – e.g., the data might need re-entering into a spreadsheet. The remaining articles did not contain their ‘raw’ data, limiting the types of analysis for which they could be used. A second assessment was undertaken of meta-studies using previously published archaeobotanical data – whilst 64% did reference the studies used, 21% did not, hindering the extent to which others can build on these studies in the future. The lack of formal credit, by way of citation, to data producers for the creation of archaeobotanical datasets may limit the motivation to make future datasets available in a reusable format.

The decisions researchers make regarding if and how to share datasets is complex, with factors including career stage, access to financial and technological resources, education and training all coming into play. But discussions of data-sharing should be undertaken across academic communities, and training should be provided as part of degrees and within professional bodies; after all, the availability of sample-level data enables the fullest future use of archaeobotanical research, and makes the most of long hours spent at the microscope.

Based on the article:
Lodwick, L., 2019. Sowing the Seeds of Future Research: Data Sharing, Citation and Reuse in Archaeobotany. Open Quaternary, 5(1), p.7. DOI: http://doi.org/10.5334/oq.62

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Cool Hyenas

Lay summary authored by Jack Tseng. The full paper can be read in Open Quaternary: http://doi.org/10.5334/oq.64

Beringia, the geographic region including parts of eastern Russia, Alaska, and western Yukon Territory, is scientifically important for understanding animal and human movements in and out of North America. Our current understanding of Ice Age fossil records in Beringia suggests that the region had a higher diversity of predatory mammals than at the present. However, fossils of large predator mammals are exceedingly rare, making a more complete understanding of why some species went extinct, whereas other survived, difficult.

Old Crow flats_(photo by Dr Duane Froese 2004)

Aerial view of the Old Crow River meandering through Old Crow Flats (Photo by Duane Froese).

The Old Crow region of northwestern Yukon Territory contains one of the richest Ice Age fossil deposits in Beringia and north of the Arctic Circle. The presence of Ice Age fossils has been known to First Nations people for hundreds of years. In the past century, more than 50,000 fossil specimens have been systematically collected from the Old Crow. Out of these specimens, we describe two fossils that belong to one of the rarest predators in the Beringian region, that of hyenas.

The hyena fossils we describe in this study belong to Chasmaporthetes, which is a group of wide-ranging predators known for their running-adapted limb characteristics. Prior to our study, Chasmaporthetes fossil sites between Asia and North America span more than 10,000 km, from Mongolia to southern United States. Although a Beringian route has been hypothesized for these hyenas, no physical evidence of the presence of Chasmaporthetes existed until this study confirmed two fossilized Chasmaporthetes teeth from the Old Crow. We can now say that a Beringian immigration route of Chasmaporthetes from Asia to North America is supported by the intermediate locale of Old Crow, north of the Arctic Circle.

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A large pile of fossil mammal bones and teeth collected from the Old Crow Basin (Photo by Grant Zazula).

The success of Chasmaporthetes in spreading throughout the world’s northern continents is evident from fossil records in Europe, Africa, Asia, and North America. However, the limited time duration of Chasmaporthetes in North America suggests that other predators may have competed with them there, preventing them becoming dominant. Our review of candidate competitor species indicates that giant short-faced bears and precursors of modern wolves may have been the most likely competitors of Chasmaporthetes in certain geographic regions of North America.

The extinction of Chasmaporthetes during the Pleistocene marked the end of running-adapted hunter-scavengers on the North American continent. Given the importance of scavengers to modern day African ecosystems, we speculate that the extinction of Chasmaporthetes may have changed the way the North American food webs functioned during the later Pleistocene, and into today.

Full paper: Tseng, Z.J., Zazula, G. and Werdelin, L., 2019. First Fossils of Hyenas (Chasmaporthetes, Hyaenidae, Carnivora) from North of the Arctic Circle. Open Quaternary, 5(1), p.6. DOI: http://doi.org/10.5334/oq.64

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Birds in Medieval Norway

This gallery contains 2 photos.

Lay summary authored by Samuel Walker. The full paper can be read in Open Quaternary: http://doi.org/10.5334/oq.58 Norway is home to over 500 bird species, with around 259 of these breeding in Norway. Recent ornithological work has shown that 22% of … Continue reading

Gallery

Where There’s Fire, There’s Smoke: The Significance of Air Circulation and Hearth Location at Paleolithic Cave Sites

Lay summary authored by Yafit Kedar. The full paper can be read in Open Quaternary: http://doi.org/10.5334/oq.52

Hearths are pivotal element in understanding the organization of space of human behavior in Paleolithic caves and rockshelter sites. While fire provided cooking facilities, warmth and light, one of the major negative products fire is smoke, which has an immediate effect on humans and may even prevent cave occupation after a short period. In this paper, we showed that hearth location and season of use are not randomly determined and can be explained using the air circulation model. The model is based on data developed by the NIST (USA), for simulating fire in closed spaces such as buildings and compartments. Smoke height can be estimated according to air circulation parameters in the cave, taking into account hearth location, size and season of use. We show that the expected smoke levels in cold season are higher than the smoke level in warm season. In addition, we showed that the preferred hearth location is near the back wall and not at the cave entrance.

Yafit hearths

Example of cave air circulation in caves in different conditions: a– example of cave air circulation in winter. b– example of a hearth in the cave’s depth during the winter season. Smoke is emitted towards the ceiling in the direction of the cave opening. c– example of the effect of hearth location at the cave’s entrance on the internal air circulation. d– example of the effect of a chimney with a hearth located at the cave’s back wall. The arrows represent air circulation, and the broken line represents the balance point between the cold and hot air flows (Figure Credit: Yafit Kedar).

Our short survey of sites has also revealed that numerous hearths were used in Paleolithic rockshelters, such as in Abric Romani and To Faraj, as opposed to single ones at caves. In rokshelters, hearths seem to represent group activity area enabled by the large entrance space characteristic of rockshelters allowing smoke to disperse quite rapidly. This is in contrast to caves, where smoke emitted from the hearth was present lower height and thus might have had an immediate effect on the occupants. Paleolithic caves are therefore expected to contain fewer hearths, located towards the back, as suggested by our study.

Our preliminary analysis suggests that cave hearths were better suited for cold season use, when heat from the fire increased the temperature difference between the cave’s interior and the external environment, resulting in faster air circulation and more efficient smoke ventilation. During the hot season, when the internal and external temperature difference is smaller, smoke ventilation is poorer. This would have led to a higher concentration of smoke in the cave and a lower smoke height, making habitation difficult. For example, Lazaret Cave and Tor Faraj rockshelter had a few small hearths in the cave’s depth with faunal and botanical remains indicating winter habitation.

Since hearths emit a great deal of smoke, it would seem that early humans must have reasoned about air circulation when positioning a hearth within a cave, in order to benefit from its many advantages.

Full Paper: Kedar, Y. and Barkai, R., 2019. The Significance of Air Circulation and Hearth Location at Paleolithic Cave Sites. Open Quaternary, 5(1), p.4. DOI: http://doi.org/10.5334/oq.52

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Data compilation describes the demise of a North American ice sheet

Lay summary authored by Joel Gombiner. The full paper can be read in Open Quaternary: http://doi.org/10.5334/oq.55

The last global climate transition occurred between 20,000 and 10,000 years ago, as the earth warmed from the last ice age into the milder Holocene epoch. In western North America, this climate transition included melting and retreat of the Cordilleran Ice Sheet, a continental ice mass that was similar in size to the modern Greenland Ice Sheet. The Cordilleran Ice Sheet covered much of western North America, extending from Washington to Alaska.

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Map showing study sites and extend of Laurentide and Cordilleran Ice Sheets. Credit: J. Gombiner.


This new data paper focuses on the retreat of the southern Cordilleran Ice Sheet. The paper describes a compilation of previously published radiocarbon ages, which will be downloadable as a spreadsheet or text file on the Open Quaternary Dataverse. The compilation contains over 60 post-glacial radiocarbon ages from 36 separate scientific papers. This geo-referenced age data describe the approximate timing of when specific locations in the region became ice-free. The regional pattern of deglaciation might help researchers to understand the interplay of factors that caused the ice sheet to retreat, such as warming of the ocean and atmosphere, increasing summer sun intensity, and rising sea level. Additionally, the retreat of the Cordilleran Ice Sheet likely set the stage for human migration into North America.

The compilation is meant to be a starting point for researchers studying the Pacific Northwest during the last deglaciation. It is not the complete picture of deglaciation, as each sample in the compilation requires interpretation and careful consideration, and the compilation highlights areas where there is not much data. It is also not the first compilation of post-glacial radiocarbon ages for this region. I relied heavily on previous compilations in assembling this new one, but also discovered additional ages in geologic maps, palynology studies, and other articles. Some journal articles were not available online, and I thank the UW Libraries scanning service for finding and scanning those articles. I hope this data will be a helpful tool for other Quaternary researchers focusing on the southern Cordilleran Ice Sheet.

Read the paper here:

Gombiner, J., 2019. Post-Glacial Radiocarbon Ages for the Southern Cordilleran Ice Sheet. Open Quaternary, 5(1), p.3. DOI: http://doi.org/10.5334/oq.55

and access the dataset here:

https://dataverse.harvard.edu/dataset.xhtml?persistentId=doi:10.7910/DVN/YGRESZ

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