The Science and Philosophy Forum

They look like dome tents.

http://www.latimes.com/science/sciencen ... story.html

It's an engraving--scratched with some kind of tool on a stone slab.

Found near Barcelona.

Upper paleolithic Hunter Gatherer archeology site.

Each of these represents a family (maybe quite different than we think of today). The need to gather around our own campfire away from the tribe as a whole may be an early need. Or, the size of the structure may have been determined by its ability to be moved, heated or by the number of prime males. It is clearly a pattern that carried down to nomadic people even today.