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Despite the vast array of different geochronological tools available, dating the Paleolithic remains one of the discipline’s greatest challenges. This review focuses on two different dating approaches: trapped charge and amino acid geochronology. While differing in their fundamental principles, both exploit time-dependent changes in signals found within crystals to generate a chronology for the material dated and hence, the associated deposits. Within each method, there is a diverse range of signals that can be analyzed, each covering different time ranges, applicable to different materials and suitable for different paleoenvironmental and archaeological contexts. This multiplicity of signals can at first sight appear confusing, but it is a fundamental strength of the techniques, allowing internal checks for consistency and providing more information than simply a chronology. For each technique, we present an overview of the basis for the time-dependent signals and the types of material that can be analyzed, with examples of their archaeological application, as well as their future potential.

The resilience of Neanderthals towards changing climatic and environmental conditions, and especially towards severely cold climates in northern regions of central Europe, is still under debate. One way to address this is to investigate multi-layered occupation in different climatic intervals, using independently-compiled paleoenvironmental and chronological data. Unfortunately, most open-air sites on the northern European Plain lack a robust chronostratigraphy beyond the radiocarbon dating range, thereby often hampering direct links between human occupation and climate. Here we present the results of integrative research at the Middle Paleolithic open-air site of Lichtenberg, Northern Germany, comprising archaeology, luminescence dating, sedimentology, micromorphology, as well as pollen and phytolith analyses. Our findings clearly show Neanderthal presence in temperate, forested environments during the Mid-Eemian Interglacial, MIS 5e and the latest Brörup Interstadial, MIS 5c/GI 22 (Lichtenberg II). For the previously known occupation Lichtenberg I, we revise the chronology from the former early MIS 3 (57 ± 6 ka) to early MIS 4/GS 19 (71.3 ± 7.3 ka), with dominant cold steppe/tundra vegetation. The early MIS 4 occupation suggests that Neanderthals could adjust well to severely cold environments and implies recurring population in the region between MIS 5 and MIS 3. The artefact assemblages differ between the temperate and cold environment occupations regarding size, blank production, typology and tool use. We argue that this distinctness can partially be explained by different site functions and occupation duration, as well as the availability of large and high-quality flint raw material. Raw material availability is in turn governed by changing vegetation cover that hindered or fostered sediment redeposition as a provider of flint from the primary source of the glacial sediments nearby.

Description, Shell beads from Bizmoune Cave (Morocco) show the early appearance and continuity of symbolic behavior among early Homo sapiens., Ornaments such as beads are among the earliest signs of symbolic behavior among human ancestors. Their appearance signals important developments in both cognition and social relations. This paper describes and presents contextual information for 33 shell beads from Bizmoune Cave (southwest Morocco). Many of the beads come as deposits dating to ≥142 thousand years, making them the oldest shell beads yet recovered. They extend the dates for the first appearance of this behavior into the late Middle Pleistocene. The ages and ubiquity of beads in Middle Stone Age (MSA) sites in North Africa provide further evidence of the potential importance of these artifacts as signals of identity. The early and continued use of Tritia gibbosula and other material culture traits also suggest a remarkable degree of cultural continuity among early MSA Homo sapiens groups across North Africa.

Basic assumptions of the single aliquot regenerative dose (SAR) protocol are tested using the violet stimulated luminescence (VSL) signal from quartz. The VSL signal is shown to be reduced to a sufficiently low background level between SAR steps, and the SAR protocol appears to adequately correct for sensitivity changes during measurement. The VSL SAR protocol can recover a large (405 Gy) laboratory beta dose within uncertainties, however the mean value for the dose recovery ratio is commonly 0.8 or less. This poor behaviour is echoed in the measurements of equivalent dose (De) for a sample with an expected De of ∼354 Gy, which underestimates De by 50–70%. Further investigations are required to understand the mechanisms underlying these underestimations in VSL SAR De values.

A series of dose recovery experiments are undertaken on grains of potassium-rich feldspar using a single aliquot regenerative dose (SAR) protocol, measuring the post-infrared infrared stimulated luminescence (post-IR IRSL) signal. The ability to successfully recover a laboratory dose depends upon the size of the test dose used. It is shown that using current SAR protocols, the magnitude of the luminescence response (Tx) to the test dose is dependent upon the size of the luminescence signal (Lx) from the prior regeneration dose because the post-IR IRSL signal is not reduced to a low level at the end of measuring Lx. Charge originating from the regeneration dose is carried over into measurement of Tx. When the test dose is small (i.e. 1%–15% of the given dose) this carry-over of charge dominates the signal arising from the test dose. In such situations, Tx is not an accurate measure of sensitivity change. Unfortunately, because the carry-over of charge is so tightly coupled to the size of the signal arising from the regeneration dose, standard tests such as recycling will not identify this failure of the sensitivity correction. The carry-over of charge is due to the difficulty of removing the post-IR IRSL signal from feldspars during measurement, and is in stark contrast with the fast component of the optically stimulated luminescence (OSL) signal from quartz for which the SAR protocol was originally designed.

A suite of 10 samples collected from an 11 m thick colluvial sequence at Voordrag, KwaZulu-Natal, South Africa, have been used to undertake a comparison of different luminescence methods. Good agreement is found between single grain quartz optically stimulated luminescence (OSL) and single grain K-feldspar post-infrared infrared-stimulated luminescence (post-IR IRSL) ages, with the exception of the basal samples where the quartz OSL signal is saturated. Multiple grain quartz OSL consistently yields ages older than single grain OSL methods. Multiple grain feldspar ages derived from the IRSL50 signal are underestimated due to anomalous fading. A previously published radiocarbon chronology yields ages that are younger than those from single grain quartz OSL and post-IR IRSL, and this is most likely due to contamination with younger carbon. Identifying the effect of saturation on the quartz OSL signal remains challenging when quartz is dated in isolation. However, using a paired quartz/feldspar dating approach is an effective way of identifying the impact of saturation on the OSL signal.

A comparative study using quartz optically stimulated luminescence (OSL) and feldspar post-infrared infrared stimulated luminescence (post-IR IRSL) was undertaken on Quaternary fluvial sediments from an unnamed tributary of the Moopetsi River in South Africa. The aim is to assess whether the post-IR IRSL signal can be used to date incompletely bleached sediments. Several post-IR IRSL signals using varying stimulation and preheat temperatures were investigated; of these the post-IR IRSL225 signal was deemed most appropriate for dating because it bleached most rapidly. The feldspar post-IR IRSL225 equivalent dose (De) values from this site are consistently larger than those from quartz OSL, probably due to differences in the bleaching characteristics of the two signals. Additionally, the post-IR IRSL225 De values within a sample showed less variation in precision than the quartz De data, possibly due to greater averaging between grains in the feldspar small aliquots. The agreement between ages based on the OSL and post-IR IRSL225 signals was better for younger samples (50 ka); the cause of this variation is unclear.