Puzzling out Neanderthal architecture.

Nature looks at some strange things Neanderthals built for… reasons… inside their cave homes:

Neanderthals built one of the world’s oldest constructions — 176,000-year-old semicircular walls of stalagmites in the bowels of a cave in southwest France. The walls are currently the best evidence that Neanderthals built substantial structures and ventured deep into caves, but researchers are wary of concluding much more.

“The big question is why they made it,” says Jean-Jacques Hublin, a palaeoanthropologist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany who was not involved in the study, which is published online in Nature on 25 May. “Some people will come up with interpretations of ritual or religion or symbolism. Why not? But how to prove it?”

The six structures are made of about 400 large, broken-off stalagmites, arranged in semi-circles up to 6.7 metres wide. The researchers think that the pieces were once stacked up to form rudimentary walls. All have signs of burning, suggesting that fires were made within the walls. By analysing calcite accreted on the stalagmites and stumps since they were broken off, the team determined that the structures were made 174,400 to 178,600 years ago.