When compared to dogs and cats in an experiment testing the ability to seek out food according to three-dimensional clues, corvids out-performed the mammals. A meta-analysis testing how often birds invented new ways to acquire food in the wild found corvids to be the most innovative birds. A 2004 review suggests that their cognitive abilities are on par with those of great apes. Despite structural differences, the brains of corvids and great apes both evolved the ability to make geometrical measurements.