Insights into the timing, intensity and natural setting of Neanderthal occupation from the geoarchaeological study of combustion structures: A micromorphological and biomarker investigation of El Salt, unit Xb, Alcoy, Spain

Abstract

Middle Paleolithic lithic and faunal assemblages throughout Eurasia reflect short-term Neanderthal occupations, which suggest high group mobility. However, the timing of these short-term occupations, a key factor to assess group mobility and territorial range, remains unresolved. Anthropogenic combustion structures are prominent in the Middle Paleolithic record and conceal information on the timing and intensity and natural setting of their associated human occupations. This paper examines a concentration of eleven combustion structures from unit Xb of El Salt, a Middle Paleolithic site in Spain through a geoarchaeological approach, in search of temporal, human impact and paleoenvironmental indicators to assess the timing, intensity and natural setting of the associated human occupations. The study was conducted using micromorphology, lipid biomarker analysis and compound specific isotope analysis. Results show in situ hearths built on different diachronic topsoils rich in herbivore excrements and angiosperm plant residues with rare anthropogenic remains. These data are suggestive of low impact, short-term human occupations separated by relatively long periods of time, with possible indicators of seasonality. Results also show an absence of conifer biomarkers in the mentioned topsoils and presence of conifer charcoal among the fuel residues (ash), indicating that fire wood was brought to the site from elsewhere. A microscopic and molecular approach in the study of combustion structures allows us to narrow down the timescale of archaeological analysis and contributes valuable information towards an understanding of Neanderthal group mobility and settlement patterns.

Fire and brief human occupations in Iberia during MIS 4: Evidence from Abric del Pastor (Alcoy, Spain)

“…Our results agree with previous data from stratigraphically higher layers within Stratigraphic Unit IV, particularly Unit IVb, - dated here to early MIS 3-, which was interpreted as a succession of at least three brief human occupation episodes 57 . They also agree with the short-term settlement patterns observed for MIS 3 at El Salt 55,56,69 . El Salt is within 5 km distance from Abric del Pastor and both sites show the same lithic raw material types, all from nearby sources, pointing to exploitation of a single river-bound territory.…”

“…Leierer et al . 56 corroborated this pattern using sedimentary evidence from the fire record and proposed relatively long periods of site abandonment, which could suggest high group mobility. Although these MIS 5 and MIS 3 data are not comparable directly due to their different degrees of temporal resolution, they generally reflect a Neanderthal population consisting of highly mobile groups occupying relatively small territories.…”

“…The good states of preservation of the sedimentary deposit, together with weak frost-induced lenticular microstructures observed microscopically 57 , suggest a generally cool or cold climate but is insufficient evidence to ascribe the sequence to MIS 4. A recent multiproxy study investigating the carbon and hydrogen isotopic values of sedimentary leaf waxes through the sequence (Units I-VI) point to a variable precipitation regime, while cryoturbation features revealed through soil micromorphology indicate generally cool conditions throughout 56,61 . Based on the anthracological record, the Middle Palaeolithic human occupations are associated with dry/semi-arid supramediterranean conditions (mean annual temperature 8–13 °C and mean annual precipitation 200–600 mm) with juniper stands, heliophilous taxa and scattered cryophilous pine stands 48,49 .

Figure 1Location of Abric del Pastor rock shelter.

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Neanderthal Spatial Patterns and Occupation Dynamics: A Focus on the Central Region in Mediterranean Iberia

“…This unit is therefore characterised by the overlapping of different occupational events, not very far apart in time, so that possible short time gaps appear blurred, to the point of not being recognisable in the vertical distribution of the remains. When human occupations are successive and repeated in the same space, over short time scales, sterile sedimentary units are difficult to define (Machado and Pérez 2016;Leierer et al 2019;Mallol et al 2019;Mayor et al 2020).…”

HumanOS: an open source nomadic software database for physical anthropology and archaeology

“…In archaeology, techniques used for data acquisition, have evolved considerably since the end of the last century because of the digital revolution. From the excavation book associated with drawings or engravings, some archaeologists today practice the site detection with satellite imagery (Baeye et al, 2016;Elfadaly & Lasaponara, 2019;Lin et al, 2014), ground-penetrating radar (GPR) (Conyers et al, 2019) or electrical resistivity tomography (ERT) (Bernardini et al, 2018), the 3D digitization of the existing (lidar, photogrammetry and Computed Tomography (CT) scan) (Davies et al, 2012;Leierer et al, 2019;Santos et al, 2017;Waagen, 2019) and hypothetical reconstruction (Ferrari & Quarta, 2019;Rua & Alvito, 2011;Themistocleous, 2017). Rescue archaeology generates a large volume of data that should be homogenized to promote their sharing and synthesis (Altschul et al, 2017;Kintigh et al, 2014).…”