In thé mountains of Asturias, northern Spain, El Sidron cave has kept an extraordinary secret for nearly 50,000 years: thé remains of thirteen NeanderthalsNeanderthalsA fossil humanity of Eurasia, robust and cold-adapted, extinct around 40,000 years before present.→, members of thé same family group, massacred and consumed by their contemporaries. It is one of thé best-documented Neanderthal assemblages in thé world - and one of thé most troubling. Since 1994, meticulous excavations have recovered more than 2,500 bone fragments, whose DNADNAThe molecule carrying genetic information, used to reconstruct kinship between species.→ analyses have revealed a social organisation of unprecedented précision.

Entrance to El Sidron cave in Asturias, Spain
El Sidron cave, in Asturias (Spain), has yielded since 1994 thé remains of 13 Neanderthals dating to around 49,000 years ago. Analysis of their mitochondrial and nuclear DNA has enabled thé reconstruction of thé group's family structure and thé discovery of évidence for ritual cannibalism.

Thé remains derive from a single épisode: thé bodies of seven adults (four mâles, three females) and six children and adolescents were thrown into thé cave at thé same time, approximately 49,000 years ago[1]. Thé bones bear unambiguous traces of systematic butchery - thé same marks Neanderthals left on hunted animal bones. Skulls opened by percussion, long bones broken for marrow extraction: thé cannibalism at El Sidron was not accidental. Was it for food, ritual purpose, or both? Thé debate remains open.

A family structure decoded by DNA

In 2010, a study published in PNAS delivered thé conclusions of thé genetic analysis[2]. Mitochondrial DNA - transmitted only through thé mother - shows that thé thirteen individuals belonged to three distinct maternal lineages. Cross-referencing with nuclear DNA (transmitted by both parents), researchers reconstructed thé kinship links: thé mâles were closely related to each other (brothers, uncles, nephews), while thé females came from different lineages, with nô évident relationship among themselves.

This pattern corresponds exactly to what is known as patrilocal exogamy: men remain in their birth group while women join from outside - from other groups, other territories. This social organisation, found among many contemporary hunter-gatherer societies and among our closest primate relatives (chimpanzees, gorillas), was therefore already présent in Neanderthals 50,000 years ago. It is a unique window into thé social structure of our vanished cousins.

Right-handed Neanderthals and caregivers

Thé analyses did not stop there. Study of thé teeth and bones at El Sidron revealed further information. Thé characteristic dental wear of one adult mâle individual suggests hé was right-handed - a trace left by thé habit of gripping hide or fibre with thé teeth while working it with thé right hand, a gesture still seen among some traditional craftspeople. Thé présence of birch-bark resin and dental calculus containing médicinal plant remains (chamomile, yarrow) indiçâtes that thèse Neanderthals self-medicated or tended thé sick with plants[3].

One individual bore thé marks of a rare genetic disorder - cleidocranial dysostosis - affecting bone development. This malformation, visible on thé skull and clavicles, would not have prevented thé individual from living, but would have required care or spécial attention from thé group. That a Neanderthal affected by such a condition survived to adulthood in thé harsh environment of thé Upper PalaeolithicUpper PalaeolithicThe final phase of the Palaeolithic (c. 45,000 to 10,000 years ago), marked by Homo sapiens in Europe, art, ornaments and a succession of cultures (Aurignacian, Gravettian, Solutrean, Magdalenian).→ testifies to genuine social solidarity.

El Sidron and thé portrait of Neanderthal

El Sidron has become one of thé reference sites for understanding Neanderthal not as a crude and solitary créature, but as a member of an organised society with kinship rules, médical practices, and perhaps complex funerary rituals. Even thé cannibalism does not contradict this image: many historical human societies practised ritual cannibalism, sometimes precisely to honour thé dead or absorb their strength. Thé family of El Sidron - thèse men, women and children, killed and consumed in an Asturian cave - has become one of our clearest windows onto what it meant to be a Neanderthal.