Teeth ‘heal’ at different rates among primate species

Lay summary authored by Ian Towle. The paper can be read in Open Quaternary: http://doi.org/10.5334/oq.48

It is well known that the outer layer of a tooth, enamel, can’t repair after it has been removed through injury, wear or a cavity. However, the underlying dentine can ‘heal’ to a certain extent, in the form of new material formation called tertiary dentine. This form of dentine forms in response to disease and wear to protect the underlying pulp chamber, and therefore ultimately protects the individual against abscesses and infection.

Gorrilla mandible Ian Towle

Gorilla mandible showing extensive tertiary dentine formation (Credit: I. Towle)

Tertiary dentine can be easily distinguished on the surface of a tooth, with its much darker appearance compared to the original dentine. It is not known if certain species have evolved to produce tertiary dentine in response to stimuli sooner, or at a quicker rate, than others.

The aim of this study was to begin to address this question by comparing the frequency of tertiary dentine in different species of primate, and to see if some species produce this material quicker than others in response to wear.

The results show that gorillas have by far the highest rate of tertiary dentine formation, with over 90% of teeth with dentine exposed through wear showing tertiary dentine. Gorillas likely evolved this high rate as protection against heavy wear, with early/more tertiary dentine formation keeping the tooth functioning for longer.

In contrast, hominins (humans and our closely related fossil relatives), exhibit a remarkably low and uniform rate of tertiary dentin formation, with all species showing a frequency of around 15%. Chimpanzees fall between these extremes, with 47% of worn teeth showing ‘healing’. Why humans and our close relatives produce tertiary dentine slower and/or later than other great apes is not known, but it may be because we evolved different ways to cope with heavy wear and dental disease, such as evolving thick enamel, or it may instead relate to dietary and behavioural differences.

No letters or arrows Ian Towle_top row

From left to right: Pan troglodytes lower right deciduous central incisor (specimen MER ii 27); Paranthropus robustus lower right central incisor (specimen SKX 3559); Gorilla gorilla gorilla lower left first premolar (specimen M 786) (Credit: I. Towle)

When more species have been studied it will be possible to give further insight into what drives tertiary dentine formation on an evolutionary scale. If, as seems likely, diet plays a crucial role, then the presence of this material in the fossil record may be useful for reconstructing diet in extinct species.

Read the paper here:

Towle, I., 2019. Tertiary Dentine Frequencies in Extant Great Apes and Fossil Hominins. Open Quaternary, 5(1), p.2. DOI: http://doi.org/10.5334/oq.48

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Reading the (Mormon) tea leaves at the bottom of packrat nests tells the story of Late Quaternary climate change in Western North America

Lay summary authored by Robert Harbert. Their full paper can be read in Open Quaternary: http://doi.org/10.5334/oq.46

During a 1980 episode of Cosmos Carl Sagan said “You have to know the past to understand the present.”2 For those of us who study geographic distributions of plants it is clear that the plant fossil record can tell us a lot about how ecosystems have changed through Earth’s history. By studying the shifts in where certain plants occur during different climatic periods we can begin to understand how present-day ecosystems may respond to anthropogenic climate change.

In this study we take this reasoning and invert it. The present can inform our understanding of the past. By taking data on the distribution of plant species today from the Global Biodiversity Information Facility (GBIF) and combining those with current climate models we can build a predictive model for climate based on local plant communities. We call this modeling protocol CRACLE (Climate Reconstruction Analysis using Coexistence Likelihood Estimation).

Here we apply CRACLE to the estimation of climate from Western North America over the past ~50,000 years. We are able to do this due to a combination of the fact that packrats (Neotoma spp.) are compulsive hoarders of plant twigs, fruit, leaves, and seeds and the arid climate preserves plant material in packrat nests (also called ‘middens’) for thousands of years. By analyzing samples of these plants from a range of time throughout this region we are able to piece together the climate history of Western North America as recorded through the changing distributions of plants.

Maker:L,Date:2017-8-31,Ver:5,Lens:Kan03,Act:Kan02,E-Y

A 14,600 year old fossilized packrat (Neotoma spp.) midden from Northern Baja California, MX. Numerous plant fragments, packrat dung, and small stones visible embedded in the matrix. Visible twigs, leaves, and seeds likely include Juniperus californica, Agave, Artemisia, Ephedra, and various cacti, composites, and grasses. Credit: R. Harbert

Our climate record shows that Western North America was 4-6°C cooler during the Last Glacial Maximum (LGM — 26-19ka) with the most pronounced departure from modern climatological averages coming during the warmer months. We also calculate that the rapidly warming climate of the period just after the LGM shows warming at a rate that is approximately 10 times slower than what is predicted for the next 100 years. During past warming periods, as glaciers melted, species migrated north in step with the changing climate, but species today must contend with climate change occurring at a rate not seen in at least the last 50 millenia. Whether or not migration will happen fast enough to prevent mass extinctions in our future remains to be seen as we find no analog for this rate of change in the packrat midden fossil record.

This record fills in a substantial gap in the terrestrial paleoclimate record of Western North America and represents a novel source of data. Many thousands more samples of fossilized packrat middens exist and are being studied. As we know more about where plants lived in the past we will be able to use CRACLE modeling to build more detailed and robust reconstructions of paleoclimate for this region.

Footnotes:
Title: ”Mormon Tea” is a common name for the plant genus Ephedra, a common component of packrat midden macrofossil assemblages.
2Sagan, C. E. (author and presenter). (1980) Episode 2: One Voice in the Cosmic Fugue [Television series episode]. In Adrian Malone (Producer), Cosmos: A Personal Voyage. Arlington, VA: Public Broadcasting Service.

Read the full paper:

Harbert, R.S. and Nixon, K.C., 2018. Quantitative Late Quaternary Climate Reconstruction from Plant Macrofossil Communities in Western North America. Open Quaternary, 4(1), p.8. DOI: http://doi.org/10.5334/oq.46

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Taking Fire Science and Practice to the Next Level: Report from the PAGES Global Paleofire Working Group Workshop 2017 in Montreal, Canada – Paleofire Knowledge for Current and Future Ecosystem Management

Lay summary authored by Katarzyna Marcisz. Their full paper can be read in Open Quaternary: http://doi.org/10.5334/oq.44

In the recent years news agencies inform about catastrophic wildfires taking place in forests in different areas worldwide. Canada (Fort McMurray 2016), Chile (Mediterranean Central Chile 2017), Portugal (Algarve 2018), the USA (California 2018), Russia (Siberia 2018) – the list is getting longer and longer every summer. Wildfires are a threat to peoples’ life and health due to smoke and dust production, burning houses or entire cities, and very severe fire can cause irreversible damage to ecosystems. Due to global warming such fires may be more frequent in the future, therefore, ecosystem managers, practitioners and policymakers (EMPPs) should take fire history, ecosystem vulnerability to fire and future risks into account when preparing forest management plans. Unfortunately, this is rare that EMPPs are contacting “Paleofire” specialists, discussing past fire data and/or ordering historical fire expertize for a given region.

To discuss how the communication between paleofire scientists and EMPPs can be improved, PAGES Global Paleofire Working group (http://pastglobalchanges.org/ini/wg/gpwg2/intro; www.paleofire.org) organized a workshop that gathered 24 scientists working on fire history, fire ecology, past fire practices fire and fire-climate relationships from boreal, temperate, Mediterranean and tropical ecosystems. The meeting took place at the Station Biologique des Laurentides, Université de Montréal and was led by Olivier Blarquez (Université de Montréal) and Pierre Grondin (Ministère des Forêts, de la Faune et des Parcs, Government of Quebec).

blog photo

Workshop excursion to Lac Geai and an Oakwood (Quercus rubra) at its northern range limit triggered lively discussions about fires as a disturbance and nature conservation. We also sampled surface lake sediments and looked at the soil. You can see charred wood found in the soil during the excursion. (Photos: Katarzyna Marcisz)

During the workshop, we discussed how the cooperation between scientists and EMPPs looks like nowadays in different countries based on the questionnaires that participants discussed with EMPPs from their home countries. Throughout these discussions we identified four challenges that we need to overcome to improve this cooperation. We realized (1) little awareness among EMPPs about what past environment sciences are, what methods and approaches are used in paleofire research in particular, and how long-term data (covering past fire activity in the past few millennia) can be helpful when preparing conservation plans; (2) that the professional language used by EMPPs is different than the one used by researchers, and that some expressions used by EMPPs carry different meaning for scientists; (3) that most of the data produced by scientists are either not available for EMPPs, or they are expressed in wrong format (e.g. excel table with data instead of graphs; raw data vs. interpreted); and that (4) costly “Paleo” expertise is often limited by the small available budget.

Therefore, in the paper we propose a scheme of cooperation between both groups that should improve their communication. We also want to encourage “Paleo” scientists to open up for the cooperation with EMPPs in the future. Decadal to millennial data carry important information about the evolution of ecosystems and this information is important for the nature conservation and management plans in the warmer world.

Read the full paper here:

Marcisz, K., Vannière, B., Blarquez, O. and GPWG2, T., 2018. Taking Fire Science and Practice to the Next Level: Report from the PAGES Global Paleofire Working Group Workshop 2017 in Montreal, Canada – Paleofire Knowledge for Current and Future Ecosystem Management. Open Quaternary, 4(1), p.7. DOI: http://doi.org/10.5334/oq.44

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What makes a dog?

Lay summary authored by Emily Lena Jones. Their full paper can be read in Open Quaternary: http://doi.org/10.5334/oq.43

Distinguishing between domestic dogs and wild canids (such as coyotes and wolves) from bone fragments alone is a perennial challenge for zooarchaeologists. The canid remains we recover from archaeological sites could often be either, based on their morphology. For this reason, in recent years archaeologists have turned to methods such as ancient DNA to determine if a canid is domestic or not. The use of ancient DNA in combination with traditional zooarchaeology has vastly increased our knowledge of the relationship between humans and both domestic dogs and wild canids.

At the same time, however, the genetics don’t tell us the whole story of human-animal relationships. We don’t know, based on an individual canid’s genetic makeup, how that animal interacted with humans. If past people treated wild canids in ways similar to how people today treat domestic dogs, this is an important insight as to how they viewed those “wild” animals! Similarly, if past people treated genetically domestic dogs in ways similar to coyotes, this tells us something about how they viewed these so-called “domestic” animals.

image

In this project, we examined canid remains (some with ancient DNA information available from a prior study) from Arroyo Hondo Pueblo (LA 12), a 14th century site in the northern Rio Grande of New Mexico, to explore these questions. We analyzed bone isotopes from the canids – a way to understand what these animals were eating, and therefore, whether people were feeding them or not – and compared these data to information on the areas from which these canids were recovered. Were the canids deliberately buried, or were their remains scattered? Were they placed in indoor spaces, or were they disposed of in middens or other exterior contexts? Our results show that the designation of “dog” via ancient DNA did not, at Arroyo Hondo, always correspond with the preferential treatment that we expected for a domestic animal. Similarly, in at least one case an animal identified as a coyote by its ancient DNA seems to have been fed by humans and was buried in a way suggestive of a domestic animal.

The findings from Arroyo Hondo suggest that genetic designations of “domestic” and “wild” canids may not reflect how the inhabitants of Arroyo Hondo saw these animals.

Full paper: Monagle, V., Conrad, C. & Jones, E.L., (2018). What Makes a Dog? Stable Isotope Analysis and Human-canid Relationships at Arroyo Hondo Pueblo. Open Quaternary. 4(1), p.6. DOI: http://doi.org/10.5334/oq.43

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Roads and Military Provisioning During the French and Indian War (1754–1763)

Lay summary authored by Martin Welker. Their full paper can be read in Open Quaternary: http://doi.org/10.5334/oq.40

The human diet is influenced by a variety of cultural and environmental factors including wealth, status, ethnicity, and urbanization, many of which have been studied extensively by archaeologists. The degree to which local infrastructure influences the distribution of goods has been less heavily investigated but is no less significant in its potential to impact human diets by enhancing the ease with which goods can be moved across the landscape. Our analysis brings to light the effects road systems had no the diets of French and Indian War (1754-1763) soldiers in Eastern North America. The French and Indian War was one of many conflicts between French and English colonists and has been recognized as the “War that made America”. Colonists increasingly came to resent an English government content to leave the construction, provisioning and even garrisoning of many frontier defenses to the Colonial governments.

Fort Shirley Excavation

English regiments sent over to lead major offensive efforts during the war were composed largely of conscripts and criminals. And following the war colonists were subjected to a series of new taxes including the Stamp Act to cover the British Crown’s expenses. Together, these served as tinder for the subsequent American Revolutionary War. In addition to its historical significance, the French and Indian War is notable in that major British campaigns in Pennsylvania, Virginia, and elsewhere drove the development of road systems and the construction of a large number of fortifications. These, including Fort Shirley in Huntington Co, PA, have been investigated by archaeologists. By studying animal bones recovered from these fortifications, our analysis demonstrates the impact that road systems had upon the diet of soldiers stationed there. We found that sites located in cities or near roads generally had far more domestic livestock (predominantly cattle and pigs) than those located further from major roads. For example, Fort Shirley, a frontier fortification, had very few domestic animal bones and soldiers relied heavily on hunting deer. Furthermore, cattle are far more common in assemblages from forts located on roads away from urban centers. These data support historic documents asserting that cattle and pigs were widely used for soldiers’ provisions. British generals leading campaigns in the Americas came to rely heavily on live animals, which could be herded to sites as an adaptation to the rough frontier conditions and poorly developed road systems. This practice likely explains the significance of cattle in many frontier assemblages.

Fort Shirley Screening

The full paper can be read in Open Quaternary: http://doi.org/10.5334/oq.40

Welker, M. et al., (2018). Roads and Military Provisioning During the French and Indian War (1754–1763): The Faunal Remains of Fort Shirley, PA in Context. Open Quaternary. 4(1), p.5. DOI: http://doi.org/10.5334/oq.40

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Expanding our editorial board

This gallery contains 36 photos.

Open Quaternary is welcoming 36 new members to its Editorial Board in July 2018. Here we introduce the new members in the slideshow below. The full editorial board can be found at https://www.openquaternary.com/about/editorialteam/.  

Gallery

Hunter-Gatherer Colonisation of Lithuania – Palaeoenvironmental & Archaeological Analysis

Lay summary authored by Felix Riede & Livija Ivanovaitė. Their full paper can be read in Open Quaternary: http://doi.org/10.5334/oq.39

Around 22,000 years ago, at the height of the last ice, northern Europe was entirely devoid of human populations. Archaeological evidence suggests that from 15,000 year ago, the environment warmed and glaciers retreated,  allowing people to once more explore higher latitudes. For the western Baltic region, this colonization sequence is pretty well established – at least in its rough outline – and consists of several migration pulses from a generally south-western trajectory, broadly coincident with the abrupt environmental changes of the Late Glacial period. In the eastern Baltic, traditional models would like to see the human colonization here as very much a parallel process to the one that unfolded further to the west. Yet, recent palaeoenvironmental research points towards considerable differences – leads and lags – between the environmental changes observed in the two regions. In addition, new thinking on archaeological taxonomies for this period has raised doubts with regard to just how robust our understanding of the Final Palaeolithic in the western Baltic actually is.

New research by a joint eastern-western Baltic team consisting of Lithuanian archaeologist Livija Ivanovaite and Danish archaeologist Felix Riede sheds new light on these thorny uncertainties. The team focused their efforts on reviewing, on the one hand, the available archaeological evidence and, on the other, recent palaeoenvironmental data for the two regions. Delving into the research history of the Lithuanian finds, their taphonomic integrity and how they have been interpreted by previous researchers reveals not only some fundamental disagreements between different schools of thought but also subtle interactions between recent political history in the Baltic region and the interpretation of these Final Palaeolithic artefacts. Importantly, this new research argues that the lithic material (Fig. 1) cannot unanimously be linked to specific cultures of the western Baltic, which opens up for alternative scenarios of when and from where these early colonists may have come.

Riede Fig 1

Fig 1. Candidate Final Palaeolithic stone tools from the territory of present-day Lithuania (image from Riede & Ivanovaitė 2018 under a CC-BY licence).

In parallel, the available palaeoenvironmental evidence suggests important differences between the two regions. By systematic ethnographic analogy, the pronounced changes in temperature and other climatic and environmental variables inferred from these data, are highly likely to have had an impact on whether, when and how Final Palaeolithic hunter-gatherers could operate in the eastern Baltic.

Overall, the conclusions of this new research are rather negative: The evidence is considered too fragmented and the archaeological material to poorly resolved to suggest detailed scenarios of this pioneer colonization process. The road ahead is clear, however: With regard to the archaeological evidence, new numerical dates should be obtained, new and ideally stratified archaeological sites must be found and alternative ways of classifying such artefacts using, for instance, replicable quantitative approaches should be discussed. With regard to the palaeoenvironment, more highly-resolved archives would, as always, help strengthen the emerging picture of regional Late Glacial environments and these should be interrogated for tephra isochrons so that we are able to directly compare palaeonevironmental changes along east-west and north-south transects.

The full paper can be read in Open Quaternary: http://doi.org/10.5334/oq.39

Riede, F. & Ivanovaitė, L., (2018). The Final Palaeolithic Hunter-Gatherer Colonisation of Lithuania in Light of Recent Palaeoenvironmental Research. Open Quaternary. 4(1), p.4. DOI: http://doi.org/10.5334/oq.39

 

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