Project

Were Neanderthals capable of abstract thinking symbolism or art. Using solid-state dosimetry to unravel the past

Publisher

Supervisor

Location

Greater Copenhagen area

Aim:

The main purpose of this project is to determine whether ancient fingerfluttings found on a cave wall in La Roche-Cotard, Central France could be the work of Neanderthals. To determine this, the student will establish a reliable chronology based on optically stimulated luminescence (OSL) using both quartz and feldspar multi-grain and single-grain signals.

Background:

Neanderthals were a species (or subspecies) of archaic humans that lived in Europe and Asia about 400,000 to 40,000 years ago. In the past couple of decades it has been hotly debated whether Neanderthals were capable of abstract thinking, symbolism or art. In the cave in La Roche-Cotard evidence of Neanderthal occupation has be found and fingerfluttings on the cave wall suggest that whomever made these, were indeed capable of abstract thinking, symbolism and art. The cave is believed to be have been sealed by sediments at least 45,000 years ago and as modern humans dispersed across Europe between 45,000 and 35,000 years ago, it may be possible to unambiguously associate the fingerfluttings with Neanderthals if an accurate and precise chronology for when the cave was sealed can be established. 

Luminescence dating is an absolute chronometer that is almost universally applicable to the sedimentary record of the past 500,000 years. Any sediment that has been exposed to daylight during transport is potentially datable using OSL. This has evolved to become one of the major chronometric tools used in Modern Human evolution and migration studies; in many cases it is the only available method.

In OSL dating the amount of energy absorbed (dose) during burial by a mineral (usually quartz or feldspar) since it was last exposed to daylight is used as a chronometer. This energy is absorbed from environmental ionising radiation, and some of it is stored by electrons held in the band gap in traps arising from defects in the crystal lattice. In the laboratory, an artificial light source is used to stimulate some of the trapped electrons. As electrons are released, light (luminescence) may be emitted during the recombination process; this luminescence can be calibrated in terms of total absorbed energy (dose). The time since the traps in the material were last emptied is then calculated by dividing the dose by the dose rate, i.e. a luminescence age refers to the time since last exposure to daylight.

Project description:

In OSL dating the main uncertainties centre both on the initial resetting of the OSL signal at the time of deposition, and post-depositional mixing. There is considerable controversy over the best way to deal with these issues, with some suggesting measurement of OSL from individual sand-sized grains and others suggesting that such single-grain ages can be over-interpreted, especially in this age range. Because of this debate, this project will explicitly test the hypothesis that standard multi-grain OSL ages are significantly inaccurate when compared to single-grain ages and independent age control (radiocarbon and rock surface dating). An alternative approach to investigate the completeness of bleaching at deposition is to compare the doses recorded by OSL signals from quartz and feldspar. Feldspar is reset by daylight >10 times more slowly than quartz, Thus, if feldspar ages are consistent with quartz ages, one can be confident that the quartz signal was completely reset, This approach provides an independent test of the usefulness of single-grain dating to detect incomplete bleaching.

Project outline:

1)      Chemical preparation of sediment samples (both quartz and feldspar) for luminescence dating

2)      Establishment of appropriate OSL measurement protocols

3)      Dose rate measurements using high-resolution gamma spectrometry

4)      Establishment of a reliable age for when the cave at La Roche-Cotard was sealed

In collaboration with

Andrew Murray, Aarhus University

Requirements

Curious mind, not afraid of the dark, interested in experimental cross-disciplinary work, meticulous, willing to contribute positively to an international and dynamic scientific environment

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Contact

Company / Organization

DTU Nutech

Name

Kristina Jørkov Thomsen

Position

Seniorforsker

Mail

krth@dtu.dk

Supervisor info

Msc in Earth and Space Physics and Engineering

Supervisor

Kristina Jørkov Thomsen

ECTS credits

30

Type

MSc thesis

MSc in Physics and Nanotechnology

Supervisor

Kristina Jørkov Thomsen

ECTS credits

30

Type

MSc thesis

Technical University of Denmark

For almost two centuries DTU, Technical University of Denmark, has been dedicated to fulfilling the vision of H.C. Ørsted – the father of electromagnetism – who founded the university in 1829 to develop and create value using the natural sciences and the technical sciences to benefit society.


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