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.
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.