The Sidrón Cave ( ast, Cueva del Sidrón) is a non-carboniferous

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

karst Karst is a topography formed from the dissolution of soluble rocks such as limestone, dolomite, and gypsum. It is characterized by underground drainage systems with sinkholes and caves. It has also been documented for more weathering-resistant ro ...

cave system located in the

Piloña Piloña () is a municipality in the province and autonomous community of Asturias, northwestern Spain. Its capital is the town of Infiesto. Piloña is bounded to the north by Villaviciosa and Colunga, to the east by Parres, to the west by Nav ...

municipality of

Asturias Asturias (, ; ast, Asturies ), officially the Principality of Asturias ( es, Principado de Asturias; ast, Principáu d'Asturies; Galician-Asturian: ''Principao d'Asturias''), is an autonomous communities of Spain, autonomous community in nor ...

, northwestern

Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , i ...

, where

Paleolithic The Paleolithic or Palaeolithic (), also called the Old Stone Age (from Greek: παλαιός ''palaios'', "old" and λίθος ''lithos'', "stone"), is a period in human prehistory that is distinguished by the original development of stone too ...

rock art In archaeology, rock art is human-made markings placed on natural surfaces, typically vertical stone surfaces. A high proportion of surviving historic and prehistoric rock art is found in caves or partly enclosed rock shelters; this type also ...

and the

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

s of more than a dozen

Neanderthal Neanderthals (, also ''Homo neanderthalensis'' and erroneously ''Homo sapiens neanderthalensis''), also written as Neandertals, are an extinct species or subspecies of archaic humans who lived in Eurasia until about 40,000 years ago. While th ...

s were found. Declared a ''"Partial Natural Reserve"'' in 1995, the site also serves as a retreat for five species of

bat Bats are mammals of the order Chiroptera.''cheir'', "hand" and πτερόν''pteron'', "wing". With their forelimbs adapted as wings, they are the only mammals capable of true and sustained flight. Bats are more agile in flight than most bi ...

s and is the place of discovery of two species of

Coleoptera Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...

(beetles).

Description

The total length of this huge complex is approximately , which contains a central hall of length and the Neanderthal fossil site, called the ''Ossuary Gallery'', which is long and wide. In 1994, human remains were found accidentally in the cave. They were initially suspected to be from the

Spanish Civil War The Spanish Civil War ( es, Guerra Civil Española)) or The Revolution ( es, La Revolución, link=no) among Nationalists, the Fourth Carlist War ( es, Cuarta Guerra Carlista, link=no) among Carlists, and The Rebellion ( es, La Rebelión, lin ...

because Republican fighters used to hide there; however, later analysis shows that the remains actually belong to Neanderthals.

Galería del Osario

The primary gallery of interest at the Sidron cave is the ''Ossuary Gallery'' or ''Tunnel of Bones'' (Galería del Osario), where the remains of several Neanderthals were found. The Galería del Osario was excavated from 2000 to 2013. The Neanderthal remains were all recovered from a single layer, ''Stratum III''. The associated archaeological assemblage consists of 53 stone tools; nonhuman bones are very scarce. The only other species present of similar size is

red deer The red deer (''Cervus elaphus'') is one of the largest deer species. A male red deer is called a stag or hart, and a female is called a hind. The red deer inhabits most of Europe, the Caucasus Mountains region, Anatolia, Iran, and parts of wes ...

. The remains of a few small mammals and gastropods were also found.

Neanderthal finds

Researchers recovered more than 2500 hominin fossil elements from the site. The

minimum number of individuals In disciplines including forensic anthropology, bioarchaeology, osteoarchaeology and zooarchaeology Minimum number of individuals, or MNI, refers to the fewest possible number of people or animals in a skeletal assemblage. It is used to determine ...

from Sidrón Cave is 13. The age of these remains of three men, three adolescent boys, four women, and three infants has been estimated to about 49,000 years. The fact that the bones are excellently preserved with very limited erosion and no large carnivore tooth marks and the unusual deposition of the bones, mixed into a jumble of gravel and mud, suggests that these Neanderthals did not die in this spot but an exterior location. A number of scenarios of how these "members of an extended family" might have ended up in a room-sized space, dubbed the ''Tunnel of Bones'' included flooding, cave collapse, and disposal by cannibals. Evidence for cannibalism includes "the presence of cut marks, flakes, percussion pitting, conchoidal scars, and adhering flakes". Projection exists that they were dropped into the cave in a single event via a collapse of nearby fissures above the site or, by influx of storm water.

Samples

Source:

Morphology

Morphologically, the El Sidrón humans show a large number of Neanderthal lineage-derived features even though certain traits place the sample at the limits of Neanderthal variation. Integrating the El Sidrón human mandibles into the larger Neanderthal sample reveals a north–south geographic patterning. The cave is in the northern portion, southern Neanderthals show broader faces with increased lower facial heights.

Ontogeny

The relatively well-preserved specimen of a juvenile Neanderthal recovered from the Galería del Osario, ''El Sidrón J1'', allowed researchers to study the

ontogeny Ontogeny (also ontogenesis) is the origination and development of an organism (both physical and psychological, e.g., moral development), usually from the time of fertilization of the egg to adult. The term can also be used to refer to the stu ...

of Neanderthals. By analyzing its

dentition Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiolo ...

, researchers estimate that ''El Sidrón J1'' was between 7 and 8 years old at the time of death. Around 36% of the juvenile specimen's remains was recovered, including key

cranial Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

, dental and

vertebral column The vertebral column, also known as the backbone or spine, is part of the axial skeleton. The vertebral column is the defining characteristic of a vertebrate in which the notochord (a flexible rod of uniform composition) found in all chordata, ...

elements. 138 fossil elements were recovered, including 30 dental elements and a complete mandible. Based on the

robustness Robustness is the property of being strong and healthy in constitution. When it is transposed into a system, it refers to the ability of tolerating perturbations that might affect the system’s functional body. In the same line ''robustness'' ca ...

of the specimen, researchers guess that the specimen was likely male. ''El Sidrón J1'' exhibits many traits of delayed maturation. At the time of death, ''El Sidrón J1's'' brain was likely not yet fully developed. ''El Sidrón J1's'' estimated

cranial capacity The size of the brain is a frequent topic of study within the fields of anatomy, biological anthropology, animal science and evolution. Brain size is sometimes measured by weight and sometimes by volume (via MRI scans or by skull volume). Neur ...

is , which is around 87% of the average adult Neanderthal cranial capacity (). At a comparable age, typical modern human juveniles reach around 95% of the average adult human cranial capacity. Additionally, the juvenile specimen exhibits an unusual developmental feature; the neurocentral

synchondrosis A synchondrosis (or primary cartilaginous joint) is a type of cartilaginous joint where hyaline cartilage completely joins together two bones. Synchondroses are different than symphyses (secondary cartilaginous joints) which are formed of fibroc ...

between his

thoracic The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the crea ...

and C1 vertebrae had not yet fused; typically, this fusion occurs around 2 years earlier in modern humans. Other paleoanthropologists like Marcia Ponce de León and Christoph Zollikofer have cautioned to interpret the brain size as sign of delayed maturation, because of the small case number and lack of statistical evidence and Tanya Smith noted that the assumption depends on the accuracy of the tooth's age

Archaeogenetics

Ancient Neanderthal

mtDNA Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial DNA ...

was partially sequenced in HVR region for three distinct Neanderthals from El Sidrón cave (441, 1253, and 1351c). Researchers also sequenced the partial nuclear genomes from several individuals from the cave. 1253 and 1351c have the same mutations at position A-911, G-977 in

exon An exon is any part of a gene that will form a part of the final mature RNA produced by that gene after introns have been removed by RNA splicing. The term ''exon'' refers to both the DNA sequence within a gene and to the corresponding sequen ...

7 of

FOXP2 Forkhead box protein P2 (FOXP2) is a protein that, in humans, is encoded by the ''FOXP2'' gene. FOXP2 is a member of the forkhead box family of transcription factors, proteins that regulate gene expression by binding to DNA. It is expressed in ...

gene, known as the "language gene", as found in present-day humans. In 2017, researchers successfully sequenced DNA from soil samples taken from Stratum III at El Sidrón. They were able to identify Neanderthal mtDNA sequences; the results suggested that the sequenced mtDNA belonged to more than one individual.

Neanderthal Y chromosome

The first sequencing of the Neanderthal

Y chromosome The Y chromosome is one of two sex chromosomes (allosomes) in therian mammals, including humans, and many other animals. The other is the X chromosome. Y is normally the sex-determining chromosome in many species, since it is the presence or abse ...

was successfully completed from a specimen from Sidrón Cave. Based on this sample, researchers estimate that Neanderthals diverged from the common human ancestor around 590,000 years ago. The Sidrón Cave Y chromosome had never been identified before from other fossil hominin specimens and is not found in modern humans. The Sidrón Cave Y chromosome coded for several

minor histocompatibility antigen Minor histocompatibility antigen (also known as MiHA) are receptors on the cellular surface of donated organs that are known to give an immunological response in some organ transplants. They cause problems of rejection less frequently than those of ...

genes that differ from that of modern humans.

Diet

Recent research investigating the Neanderthals remains recovered from El Sidrón have provided evidence that their diet would have consisted primarily of pine nuts, moss and mushrooms. This is contrasted by evidence from other European locations which point to a more carnivorous diet.

References

External links

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{{DEFAULTSORT:Sidron Cave Prehistoric sites in Spain Caves of Spain Stone Age sites in Europe Landforms of Asturias Geography of Asturias Neanderthal sites Paleolithic Europe Bien de Interés Cultural landmarks in Asturias