Survivor bias. In Europe, art painted on external walls or cliffs, would not survive elements for 30k years. Caves have extremely stable microclima (humidity, temperature, UV light exposure). In modern times paintings are endangered by breath and heat emissions from visitors!!
I can not believe "educated" people would not come with this solution, and instead have to invent this spiritual stuff.
I can not believe "educated" people would not come with this solution, and instead have to invent this spiritual stuff.