André Debénath

How Neanderthal molar teeth grew

Growth and development are both fundamental components of demographic structure and life history strategy. Together with information about developmental timing they ultimately contribute to a better understanding of Neanderthal extinction. Primate molar tooth development tracks the pace of life history evolution most closely, and tooth histology reveals a record of birth as well as the timing of crown and root growth. High-resolution micro-computed tomography now allows us to image complex structures and uncover subtle differences in adult tooth morphology that are determined early in embryonic development. Here we show that the timing of molar crown and root completion in Neanderthals matches those known for modern humans but that a more complex enamel–dentine junction morphology and a late peak in root extension rate sets them apart. Previous predictions about Neanderthal growth, based only on anterior tooth surfaces, were necessarily speculative. These data are the first on internal molar microstructure; they firmly place key Neanderthal life history variables within those known for modern humans.

Single-grain OSL chronologies for Middle Palaeolithic deposits at El Mnasra and El Harhoura 2, Morocco: implications for Late Pleistocene human-environment interactions along the Atlantic coast of northwest Africa.

Optically stimulated luminescence (OSL) measurements were made on individual, sand-sized grains of quartz from Middle Palaeolithic deposits at two cave sites (El Harhoura 2 and El Mnasra) on the Atlantic coast of Morocco. We were able to calculate OSL ages for 32 of the 33 samples collected from the Middle Palaeolithic deposits, including the earliest and latest Aterian levels at both sites. These ages reveal periods of occupation between about 110 and 95 ka (thousands of years ago), and at ~75 ka. A late Middle Palaeolithic occupation of El Harhoura 2 is also recorded at ~55 ka. Our single-grain OSL chronologies largely support previous age estimates from El Mnasra and other sites along the Atlantic coast of Morocco, but are generally more precise, reproducible and stratigraphically more coherent (i.e., fewer age reversals). We compare the single-grain ages for El Harhoura 2 and El Mnasra with those obtained from single- and multi-grain OSL dating of Middle Palaeolithic deposits in the nearby sites of Contrebandiers and Dar es-Soltan 1 and 2, and with records of past regional environments preserved in sediment cores collected from off the coast of northwest Africa. A conspicuous feature of the new chronologies is the close correspondence between the three identified episodes of human occupation and periods of wetter climate and expanded grassland habitat. Owing to the precision of the single-grain OSL ages, we are able to discern gaps in occupation during Marine Isotope Stages 5 and 4, which may represent drier periods with reduced vegetation cover. We propose that these climatic conditions can be correlated with events in the North Atlantic Ocean that exert a major control on abrupt, millennial-scale fluctuations between wet and dry periods in northwest and central North Africa.

Taphonomy and Zooarchaeology of a Mousterian Faunal Assemblage from La Quina, Charente, France

AbstractThe 1986 excavations at the Mousterian site of La Quina, Charente, France included a witness section left intact by an earlier researcher, Germaine Henri-Martin. Zooarchaeological study of material from this witness section was designed to evaluate the effects of a number of different natural and human factors. This analysis demonstrated that the assemblage was actually the product of a number of different processes, some natural and some human, operating one after the other. The first of these processes was the accumulation offaunal remains by humans, a process that included some damage to the bones and probably some effect on the relative frequencies of different elements. This wasfollowed by damage and probably partial destruction by carnivores, and then by small-scale displacement by stream action. This complex series of events obscured details of the human activities originally responsiblefor the accumulation, although some behavioral information could still be extracted.

Identification of the Last Glacial Maximum in the Upper Paleolithic of Portugal Using Magnetic Susceptibility Measurements of Caldeirao Cave Sediments

We have sampled Upper and Middle Paleolithic sediments in Caldeirao Cave, Portugal, for paleoclimatic analysis. This work involved measuring magnetic susceptibility (MS) on continuous vertical profiles of a series of ∼8 cc sediment samples, and using the MS data as a paleoclimate proxy. Previous work has shown that caves can be ideal recorders of paleoclimatic variations because they are protected environments. Pedogenesis outside the cave during time of cool climate produces sediments with low MS magnitudes, while warmer climates yield higher MS magnitudes. Eroded soils collect in caves in sediment sequences where futher pedogenesis and biological disturbance is minimal. Continuously sampled profiles of those sediments found in an archaeological context then allow paleoclimatic estimates for all archaeological levels. Results of our work here include identification of the last glacial maximum, at ca. 24,000–22,000 B.P. (calibrated), defined by very low MS values found in basal Solutrean levels in the cave. Distinctive ca. 2500 year Neo-glacial cycles, defined by the MS data within the Early Upper Paleolithic and Solutrean, are consistent with published 14C duration estimates for the Upper Paleolithic in Caldeirao Cave.

Two new hominin cranial fragments from the Mousterian levels at La Quina (Charente, France)

Excavations in the first half of the 20 century of the Mousterian levels at the well known site of La Quina (Charente, France) yielded an important series of human remains (Martin, 1923; Henri-Martin, 1966; Verna, 2006). These remains include one adult skeleton, a juvenile cranium, and 27 bone fragments and teeth (Verna, 2006) attributed to late Neandertals from Marine Isotope Stage (MIS) 4–3. From 1985 to 1994, new excavations led by A. Debénath and A.J. Jelinek further investigated these Mousterian deposits and discovered new human remains (Debénath and Jelinek, 1998), including two skull fragments that we describe here. After the reassessment of the whole series (Verna, 2006), these two new fragments were numbered La Quina 28 and 34 (LQ28, LQ34). They come from deposits located at the base of the sequence (Fig. 1), which yielded Quina type Mousterian and a fauna consisting mainly of reindeer, horse, and bison (Debénath and Jelinek, 1998). LQ28, a frontal fragment, was discovered in 1988 in a 20 cm thick archaeologically rich layer of gray-brown sandy clay (level L). LQ34, a parieto-occipital fragment, was unearthed in 1993 in layer N. This 20 cm thick layer consists of greenish-gray sandy clay containing many faunal remains broken into large pieces and

Dating the Middle Paleolithic deposits of La Quina Amont (Charente, France) using luminescence methods

The site of La Quina Amont, located in the Charente region, is one of the most important sites in southwestern France for studying major changes in human behaviors from the Middle Paleolithic (MP) to the Early Upper Paleolithic (EUP). Extensively excavated over the past 50 years, numerous dating studies have been focused on the Upper Paleolithic deposits using radiocarbon on bone collagen and thermoluminescence (TL) on heated flints; however, the Mousterian levels remain undated due to the scarcity of suitable materials. Our investigations aimed to provide for the first time a chronological framework for the site using luminescence dating methods on different minerals contained in the sediments. Coarse grains of quartz were dated using the optically stimulated luminescence (OSL) technique, and polymineral fine grains were dated using both infrared (IRSL) and post-infrared (pIR-IRSL) stimulated luminescence signals. OSL, IRSL and pIR-IRSL results were combined with available TL and radiocarbon data sets to propose a chronology for the site. The agreement between these methods provides key insights into the sedimentological processes involved in the site formation and into the chronology of the human occupations. In particular, it shows that the sequence spans almost ∼20,000 years (20 ka). Moreover, the new chronological framework suggests that the makers of the Quina lithic technocomplex (LTC), who were reindeer hunters, inhabited the site from the end of marine isotope stage (MIS) 4 to the beginning of MIS 3. We also show that Levallois and Discoidal industries occurred successively under temperate paleoclimatic conditions, during MIS 3 but not after ∼40 ka. Finally, we compare the Quina LTC dataset with other sites in southern France in order to shed light upon the variability in Mousterian industries of this region.