El Sidrón is a karst cave located in the Asturias region of northern Spain, where the remains of at least 12 Neanderthals have been discovered. The cave system stretches into the hillside a length of approximately 3,700 meters (2.5 miles), with a central hall of approximately 200 m (650 feet). The Neanderthal site is located in the Ossuary Gallery, ~28 m (90 ft) long and 12 m (40 ft) wide. All of the human remains found at the site were recovered within a single stratum, called III.
Preservation of the bones is excellent, with very limited trampling or erosion and no large carnivore toothmarks. The archaeological assemblage is not in its original location: researchers believe that the original site was outside of the cave, and that the human remains and stone tools were dropped into the cave in a single event via a collapse of nearby fissures above the site.
Artifacts at El Sidrón
Over 400 lithic artifacts have been recovered from the Neanderthal occupation at El Sidron, all made from local and mostly chert and quartzite. Side scrapers, denticulates, a hand axe, and several Levallois points are among the stone tools. These artifacts represent a Mousterian assemblage; the makers of the lithics were Neanderthals.
At least 18% of the stone tools can be refitted to two or three silex cores, indicating that they were made at the primary location of the site assemblage. There are almost no animal bone. Although there are not carnivore tooth marks on the bone, the bones are heavily fragmented and show cutmarks made by stone tools, indicating that they were almost certainly killed and cannibalized.
Evidence for cannibalism includes cut marks, flaking, percussion pitting, conchoidal scars and adhering flakes on the bones. Long bones show deep scars; several bones have been cracked open to obtain marrow or brains. The bones of the neanderthals have evidence of nutritional stress during their entire lives, and these data together lead researchers to believe this family was a victim of survival cannibalism by another group.
The Ossuary Gallery (Galería del Osario in Spanish) was discovered in 1994 by cave explorers, who stumbled across human remains in a small lateral gallery. The bones all lie within an area of about 6 square meters, and geological analysis of the sediments suggests that the bones dropped into the cave via a vertical shaft, in a massive flow deposit, probably resulting from a flood event after a thunderstorm.
The bone assemblage at El Sidrón is almost exclusively Neanderthal human remains. A total of 12 individuals has been identified as of 2013. Individuals so far identified at El Sidrón include six adults (three males and one female), three adolescents between 12 and 15 years of age, two juveniles between 5 and 9 years of age, and one infant.
Analysis of mitochondrial DNA supports the hypothesis that the 12 individuals represent a family group: seven of the 12 individuals share the same mtDNA haplotype. In addition, dental anomalies and other physical features are shared by some of the individuals (Lalueza-Fox et al. 2012; Dean et al.).
Dating El Sidrón
Calibrated AMS dates on three human specimens ranged between 42,000 and 44,000 years ago, with an average calibrated age of 43,179 +/-129 cal BP. Amino acid racemization dating of gastropods and human fossils support the dating.
Direct radiocarbon dates on the bones themselves were inconsistent at first, but new protocols were established for El Sidrón to remove contamination at the site. Bone fragments recovered using the new protocol were radiocarbon dated, obtaining a secure date of 48,400 +/-3200 RCYBP, or the early part of the geological stage called Marine Isotope 3 (MIS3), a periodo of rapid climate fluctuations.
Excavation History at El Sidrón
El Sidrón has been known since the beginning of the 20th century, and it was used as a hiding place during the Spanish Civil War by republicans hiding from Nationalist troops. The archaeological components of El Sidrón were accidentally discovered in 1994, and the cave has been intensively excavated since 2000 by a team led by Javier Fortea at the Universidad de Oviedo; since his death in 2009, his colleague Marco de la Rasilla has continued the work.
As of 2012, over 1,800 Neanderthal fossil remains and 400 lithic tools have been recovered, making El Sidron one of the largest collections of Neanderthal fossils in Europe to date.
Bastir M, Rosas A, García Tabernero A, Peña-Melián A, Estalrrich A, de la Rasilla M, and Fortea J. 2010. Comparative morphology and morphometric assessment of the Neandertal occipital remains from the El Sidrón site (Asturias, Spain: years 2000–2008). Journal of Human Evolution 58(1):68-78.
Burbano HA, Hodges E, Green RE, Briggs AW, Krause J, Meyer M, Good JM, Maricic T, Johnson PLF, Xuan Z et al. 2010. Targeted Investigation of the Neandertal Genome by Array-Based Sequence Capture. Science 238:723-725.
Dean MC, Rosas A, Estalrrich A, García-Tabernero A, Huguet R, Lalueza-Fox C, Bastir M, and de la Rasilla M. 2013. Longstanding dental pathology in Neandertals from El Sidrón (Asturias, Spain) with a probable familial basis. Journal of Human Evolution 64(6):678-686.
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Lalueza-Fox C, Rosas A, and Rasilla Mdl. 2012. Palaeogenetic research at the El Sidrón Neanderthal site. Annals of Anatomy - Anatomischer Anzeiger 194(1):133-137.
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Santamaría D, Fortea J, De La Rasilla M, Martínez L, Martínez E, Cañaveras JC, Sánchez-Moral S, Rosas A, Estalrrich A, García-Tabernero A et al. 2010. The Technological and Typological Behaviour of a Neanderthal Group from El Sidrón Cave (Asturias, Spain). Oxford Journal Of Archaeology 29(2):119-148.
Wood RE, Higham TFG, De Torres T, TisnÉRat-Laborde N, Valladas H, Ortiz JE, Lalueza-Fox C, SÁNchez-Moral S, CaÑAveras JC, Rosas A et al. . 2013. A new date for the Neanderthals from El Sidrón Cave (Asturias, Northern Spain). Archaeometry 55(1):148-158.