"16. A Przewalski horse showing the contours of the face and sharp color demarcation around the muzzle depicted in figure 15. (Photo by Sandra Olsen)" (Olsen 2003:5)
With reasonable explanations for the marks on the carvings and paintings that might resemble harnessing, and with a reasonable explanation for wood chewing by horses, I believe that the preponderance of evidence is against the proposed domestication of horses in the paleolithic period. Additionally, I can think of no way that evidence of crib-biting could be deduced from the paintings or carvings of the Paleolithic period. Therefore, with this analysis, I think that we can make an informed judgement on the question of domestication and, to me, all the evidence argues against it.