Though dog breeds are widely considered to vary in intelligence—have there been any attempts to quantify it?
Yes; take a look at this, and the generic wikipedia page. One of the more visible tests is the number of times a new command must be repeated to be learned. Overall, there’s not too much agreement because there are a number of different interpretations of what it means for a dog to be intelligent, and no one has (to my knowledge) done the factor analysis to look for g in dogs.
We do have such a test battery for primates, though, the Primate Cognitive Test Battery (came up 2014 in showing chimp intelligence is, of course, heritable). Cross-species comparisons have been done and don’t show much difference aside from humans: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3317657/ (and from a different avenue, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3049098/ ). This is a bit surprising to me but I suppose it’s not like we’ve deliberately bred any of those species for intelligence or anything.
Yes; take a look at this, and the generic wikipedia page. One of the more visible tests is the number of times a new command must be repeated to be learned. Overall, there’s not too much agreement because there are a number of different interpretations of what it means for a dog to be intelligent, and no one has (to my knowledge) done the factor analysis to look for g in dogs.
We do have such a test battery for primates, though, the Primate Cognitive Test Battery (came up 2014 in showing chimp intelligence is, of course, heritable). Cross-species comparisons have been done and don’t show much difference aside from humans: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3317657/ (and from a different avenue, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3049098/ ). This is a bit surprising to me but I suppose it’s not like we’ve deliberately bred any of those species for intelligence or anything.