Why are these 32 symbols found in ancient caves all over Europe?

Why are these 32 symbols found in ancient caves all over Europe?


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Date Common Era
Rock Art Type
Petroglyph (Engraving),Pictograph (Painting)
Rock Art Tools
Rock Art Style
Geometric
Rock Art Subject Matter
Geometric Shape
Color
Width (m)
Height (m)
Depth (m)
Site Biome
Ground Surface
Site Type
Site Orientation
No. of Sites
No. of Panels
No. of Motifs
Condition
Issues
Physical Work