Reconstruction
The Almonda karst system near Torres Novas drains a limestone massif in central Portugal, and its galleries have been opening and closing to the outside for hundreds of thousands of years. In one of them, Gruta da Aroeira, a partial human cranium was found in 2014 cemented into breccia so hard that it had to be cut out as a block and read by CT scan. Aroeira 3 preserves the brow and orbits of an adult, and it came out of layer X alongside Acheulean bifaces, making it the only Middle Pleistocene European cranium recovered with handaxes in a cave context.
Uranium-thorium ages on calcite crusts that formed on the cranium itself give 390,000 and 408,000 years. The wider bracket for the deposit runs from about 390,000 to 436,000 years, and the occupation is conventionally placed near 400,000 years ago, in Marine Isotope Stage 11.
The fire evidence was published separately and rests on converging measurements rather than a visible feature. Forty-three burnt bone fragments were examined: roughly half fully carbonised, others carbonised or calcined in part, the calcined pieces implying high temperatures. Charcoal indicates incomplete combustion in the range of 300 to 400 degrees. Eight quartzite items are reddened or blackened, and one cobble carries a magnetic signature of heating. Soil micromorphology, infrared spectroscopy, magnetic properties, elemental analysis, organic chemistry and spatial plotting were combined to make the case, which stands as among the oldest evidence for anthropogenic fire in south-western Europe.
What the case does not include is a hearth. The burnt material occurs as two discrete accumulations in layers Xb and Xc, and the excavators read them as combustion features scattered after use rather than as intact fireplaces. They are explicit that their data cannot define the exact nature of the activities involved, though the concentration of heat damage in a small area argues against a wildfire and for burning in one place.
Nor is there a butchered meal. The bones from layer X are heavily fragmented, averaging around twenty millimetres, and mostly unidentifiable. Where they can be named they are deer, tortoise and small vertebrates, with beaver and macaque elsewhere in the sequence. No cut marks or other anthropogenic modification were detected on them. Fire residues and animal bone lie in the same deposits, which is suggestive, but the link between the two is circumstantial rather than demonstrated, and no cooking is shown.
Taken together the site gives something rare and worth stating precisely: a securely dated Middle Pleistocene cave occupation at the far western edge of Europe with a human face, a handaxe toolkit and the chemical residue of fire, all in one layer, and honest gaps between them.
Historical context
Around 400,000 years ago in the warm Marine Isotope Stage 11, Iberia was a mosaic of woodland and open ground that acted as a southern refuge for animals and people alike, holding red deer, horse, aurochs, tortoise, macaque and beaver. The hominins working Acheulean handaxes across western Europe were pre-Neanderthals, and fire was appearing in the archaeological signal at scattered sites in Britain, France and Germany within the same few tens of thousands of years. Five hundred kilometres to the north-east, the Atapuerca shaft was accumulating bodies without any fire at all. No modern humans existed.
Evidence
Archaeological
StrongThe Aroeira 3 cranium was recovered in situ from cemented breccia in layer X, extracted as a block and studied by CT, in direct association with Acheulean bifaces. The stratigraphic context and the artefact association are secure.
Dating
StrongUranium-thorium ages of 390,000 and 408,000 years on calcite crusts formed on the cranium give minimum constraints on the fossil itself, within a site bracket of roughly 390,000 to 436,000 years placing the occupation in MIS 11.
Residue chemical
ModerateBurnt bone, charcoal and heat-altered quartzite were characterised by micromorphology, FTIR, magnetic properties, EDX, organic chemistry and spatial analysis. Reported temperature proxies differ, with charcoal indicating 300 to 400 degrees while calcined bone implies substantially hotter exposure.
Preparation method
LimitedFire was present but no structured hearth was identified. The burnt material forms two discrete accumulations in layers Xb and Xc interpreted as combustion features scattered after use, and the analysts state their data cannot define the exact nature of the hominin activities. Cooking is not demonstrated.
Zooarchaeological
LimitedFaunal remains from layer X are heavily fragmented, averaging about twenty millimetres, and no cut marks or other anthropogenic modification were detected. The association between the fire residues and food processing is therefore circumstantial.
Food identification
LimitedIdentifiable taxa include deer, tortoise and small vertebrates, with beaver and macaque in the wider sequence. Because no butchery marks were found, these animals are established as present rather than as demonstrated human food.
Geographic attribution
StrongThe site is securely located in the Almonda karst system at Torres Novas in central Portugal, one of the best-documented cave sequences in western Iberia.
Sources
- 1.Joan Daura, Montserrat Sanz, Juan Luis Arsuaga, et al. (2017). New Middle Pleistocene hominin cranium from Gruta da Aroeira (Portugal). Proceedings of the National Academy of Sciences 114(13), 3397-3402. doi:10.1073/pnas.1619040114Scientific literature
- 2.Montserrat Sanz, Joan Daura, Dan Cabanes, et al. (2020). Early evidence of fire in south-western Europe: the Acheulean site of Gruta da Aroeira (Torres Novas, Portugal). Scientific Reports 10(1), 12053. doi:10.1038/s41598-020-68839-wScientific literature
- 3.Joan Daura, Montserrat Sanz, Marianne Deschamps, et al. (2018). A 400,000-year-old Acheulean assemblage associated with the Aroeira-3 human cranium (Gruta da Aroeira, Almonda karst system, Portugal). Comptes Rendus Palevol 17(8), 594-615. doi:10.1016/j.crpv.2018.03.003Scientific literature
- 4.Juan Manuel Lopez-Garcia, Hugues-Alexandre Blain, Montserrat Sanz, et al. (2018). Refining the environmental and climatic background of the Middle Pleistocene human cranium from Gruta da Aroeira (Torres Novas, Portugal). Quaternary Science Reviews 200, 367-375. doi:10.1016/j.quascirev.2018.10.003Scientific literature
- 5.Roman Croitor, Montserrat Sanz, Joan Daura (2019). Deer remains from the Middle Pleistocene site of Gruta da Aroeira (Portugal): Iberian faunal endemism and implications for hominin paleobiogeography. Quaternary Science Reviews 225, 106022. doi:10.1016/j.quascirev.2019.106022Scientific literature
- 6.Wil Roebroeks, Paola Villa (2011). On the earliest evidence for habitual use of fire in Europe. Proceedings of the National Academy of Sciences 108(13), 5209-5214. doi:10.1073/pnas.1018116108Scientific literature
Limitations
- majorpreparation method
The card's title, 'Aroeira Cave Hearths', asserts something the primary literature explicitly denies. Sanz et al. (2020) identified no structured hearths at the site. The burnt material forms two discrete accumulations in layers Xb and Xc which they interpret as the post-depositional scattering of a combustion feature, and they state directly that their data do not allow the exact nature of the hominin activities to be defined. The card should describe burnt residues and heat-altered material, not hearths.
- majorgeographic attribution
The card is filed as contributing to food trade and exchange. Nothing at Gruta da Aroeira evidences trade or exchange of any kind. This is a 400,000-year-old cave occupation with a locally sourced Acheulean toolkit; no exotic raw materials, transported foodstuffs or exchange relationships are reported in any of the published work. The trade attribution cannot be carried by the evidence and should be removed.
- moderatezooarchaeological
The card states that burned materials 'connect fire use with Middle Pleistocene life', which risks implying cooking. No cut marks or other anthropogenic modification were detected on the layer X fauna, which is fragmented to a mean length of about twenty millimetres. Fire residues and animal bone co-occur in the same deposits, but the connection between burning and food processing at this site is circumstantial and no cooking is demonstrated.
- moderatedating
The card's range of 400,000 to 390,000 BCE sits at the young end of the published bracket and treats minimum constraints as determinations. The uranium-thorium ages of 390,000 plus or minus 14,000 and 408,000 plus or minus 18,000 years come from calcite crusts formed on the cranium and are therefore minimum ages for it; the published bracket for the fossil is 390,000 to 436,000 years. The card's window excludes the older half of that range.
- minorresidue chemical
Reported burning temperatures at this site come from different proxies that do not agree closely. Charcoal indicates incomplete combustion at roughly 300 to 400 degrees, while the calcined bone fragments imply markedly higher exposure. Any single temperature figure quoted for Aroeira should be attributed to its proxy rather than presented as the temperature of the fire.
- minorarchaeological
The card's phrasing implies the cranium, the tools and the burnt material form one associated event. The Aroeira 3 cranium comes from layer X, while the two burnt accumulations are in sub-units Xb and Xc, representing separate occupation horizons. The association is stratigraphic and close but not a single moment.
