Question: if dogs had apposible thumbs would they be able to stand and behave like us?

Vera Weisbecker answered on 22 Jun 2011:

Yes and No…Opposable thumbs as such don’t change anything in the rest of the skeleton and behaviour. But if dogs had evolved opposable thumbs a few million years ago, it is possible that those dogs whose behaviour was more human-like and who could stand upright would have had a selective advantage because it allowed them better use of their thumbs. In that case, dogs would have evolved to be like humans.