Thanks, Arthur - this fascinates me too. I was taught by the famous Northrop Frye at the U of T who remarked to a student one day in class, "if you can't say it, you don't know it." It made me think about language and thinking and the self-talk that goes on inside our heads and when exactly it happened that cave men heard a voice speaking inside them. Fascinating...

The cave ar t is from the Chauvet-Pont-d'Arc Cave in the Ardèche department of southern France and is 30, 000 yrs. old. The 3D effect comes from their having the ability to use the natural contours of the cave wall to make their images stand out and appear life-like.

As for the Egyptians, I believe they inherited an already developed more ancient civilization that were megalithic builders - see Youtube vids by UnchartedX -

- he has many lectures exploring this topic. As for writing and painting, they were in a more primitive stage writing in pictograms and drawing in 2D as you rightly point out.

Always a pleasure to converse with you, my friend :)