Academic journal article Antiquity

Neanderthals, Trees and Dental Calculus: New Evidence from El Sidron

Academic journal article Antiquity

Neanderthals, Trees and Dental Calculus: New Evidence from El Sidron

Article excerpt

Introduction

The study of dental calculus from past human and hominin populations is a promising field of investigation, especially for accessing information on plant use in pre-agricultural and non-sedentary populations where other lines of evidence can be poor. Dental calculus is a mineralised deposit of calcium phosphate that adheres to tooth enamel. It is formed by the activity of bacteria, which are energised by salivary sugars to form plaque. If this is not removed, it can calcify in as little as two weeks (Lieverse 1999). This formation process ceases at death because it requires minerals present in the saliva (MacPhee & Cowley 1975). Once plaque has calcified, it can survive for extended periods. It is found on teeth in most ancient human populations, and has even been identified on Miocene apes that lived between 8 and 12 million years ago (Hershkovitz et al. 1997). Analyses of material found embedded in ancient dental calculus in human and hominin populations have provided direct evidence of a variety of debris, including human cells and mineralised bacterial structures (Hardy et al. 2012, in press; Buckley et al. 2014; Warinner et al. 2014).

Previous studies have mainly focused on dietary reconstruction, and the majority of the finds have been interpreted as the remains of the deliberate consumption of plant-derived food (Henry & Piperno 2008; Piperno & Dillehay 2008; Hardy et al. 2009; Li et al. 2010; Weslowski et al. 2010; Henry et al. 2012, 2014; Mickleburgh & Pagan-Jimenez 2012). Several studies have, however, highlighted non-nutritional information from dental calculus, including evidence for both non-masticatory use of the teeth and the presence of inhaled or unconsciously ingested material (Blondiaux & Charlier 2008; Blatt et al. 2011; Hardy et al. 2012, in press; Buckley et al. 2014; although see Weslowski et al. 2010 for an alternative interpretation). Here, we present evidence in the form of chemical compounds and non-dietary debris from non-edible material recovered in the dental calculus of the Neanderthal population at El Sidron, northern Spain. An earlier study of this material revealed evidence for consumption of cooked starchy plant food, exposure to wood smoke, the presence of bitumen and the use of two non-nutritional plants; due to their medicinal qualities, ingestion of these plants was interpreted as evidence for self-medication (Hardy et al. 2012, 2013).

Materials and methods

The Neanderthal fossil assemblage from El Sidron is dated to approximately 49 kya (Wood et al. 2013). The minimum number of individuals identified at the site is currently 13 (Rosas et al. 2013), including seven adults (three female, three male, one unidentified), three adolescents (two male, one possible female), two juveniles (one male) and one infant (Lalueza-Fox et al. 2011; Rosas et al. 2012, 2013). The analysis of non-masticatory dental wear has revealed that all individuals were right-handed (Estalrrich & Rosas 2013) and all used their mouth as a third hand (Estalrrich & Rosas 2015).

Dental calculus was extracted from five adult individuals, and the samples were degraded and examined for their surviving content. Optical microscopy was used for the microfossil material, and the samples were also analysed using sequential thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) and pyrolysis-gas chromatography mass spectrometry (Py-GC-MS) (Hardy et al. 2012). A second study, focused on the evidence for non-edible material, was conducted using a Zeiss compound microscope with magnifications up to x800, at the Ancient Starch Laboratory, University of Leicester, using the original mounted microscope slides.

Results

A fragment of non-edible conifer wood tissue with a small fleck of dental calculus still attached to it (Figure 1B) was identified from the material extracted from the lower left first molar (LLM1) of sample 1327h (adult 5), a right-handed (Estalrrich & Rosas 2013) adult female (Lalueza-Fox et al. …

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