Neanderthal
Fire and construction

Many Mousterian sites have evidence of fire, some for extended periods of time, though it is unclear whether they were capable of starting fire or simply scavenged from naturally occurring wildfires. Indirect evidence of fire-starting ability includes pyrite residue on a couple of dozen bifaces from late Mousterian (c. 50,000 years ago) northwestern France (which could indicate they were used as percussion fire starters), and collection of manganese dioxide by late Neanderthals which can lower the combustion temperature of wood. They were also capable of zoning areas for specific activities, such as for knapping, butchering, hearths and wood storage. Many Neanderthal sites lack evidence for such activity perhaps due to natural degradation of the area over tens of thousands of years, such as by bear infiltration after abandonment of the settlement.

In a number of caves, evidence of hearths has been detected. Neanderthals likely considered air circulation when making hearths as a lack of proper ventilation for a single hearth can render a cave uninhabitable in several minutes. Abric Romaní rock shelter, Spain, indicates eight evenly spaced hearths lined up against the rock wall, likely used to stay warm while sleeping, with one person sleeping on either side of the fire. At Cueva de Bolomor, Spain, with hearths lined up against the wall, the smoke flowed upwards to the ceiling, and led to outside the cave. In Grotte du Lazaret, France, smoke was probably naturally ventilated during the winter as the interior cave temperature was greater than the outside temperature; likewise, the cave was likely only inhabited in the winter.

In 1990, two 176,000-year-old ring structures, several metres wide, made of broken stalagmite pieces, were discovered in a large chamber more than 300 m (980 ft) from the entrance within Grotte de Bruniquel, France. One ring was 6.7 m × 4.5 m (22 ft × 15 ft) with stalagmite pieces averaging 34.4 cm (13.5 in) in length, and the other 2.2 m × 2.1 m (7.2 ft × 6.9 ft) with pieces averaging 29.5 cm (11.6 in). There were also four other piles of stalagmite pieces for a total of 112 m (367 ft) or 2.2 t (2.4 short tons) worth of stalagmite pieces. Evidence of the use of fire and burnt bones also suggest human activity. A team of Neanderthals was likely necessary to construct the structure, but the chamber's actual purpose is uncertain. Building complex structures so deep in a cave is unprecedented in the archaeological record, and indicates sophisticated lighting and construction technology, and great familiarity with subterranean environments.

The 44,000-year-old Moldova I open-air site, Ukraine, shows evidence of a 7 m × 10 m (23 ft × 33 ft) ring-shaped dwelling made out of mammoth bones meant for long-term habitation by several Neanderthals, which would have taken a long time to build. It appears to have contained hearths, cooking areas and a flint workshop, and there are traces of woodworking. Upper Palaeolithic modern humans in the Russian plains are thought to have also made housing structures out of mammoth bones.
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