Comments by "Stephanie Who " (@stephjovi) on "Why are these 32 symbols found in caves all over Europe | Genevieve von Petzinger | TED" video.

Honest question maybe someone knows : how do we know those caves were that narrow thousands of years ago? Maybe they were wider? Couldn't they just go in try to find out if you get out elsewhere? Maybe left marks to show how far they got?
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