A paper just published in Psychological Science:
Corvids (birds of the family Corvidae) display intelligent behavior previously ascribed only to primates, but such feats are not directly comparable across species. To make direct species comparisons, we used a same/different task in the laboratory to assess abstract-concept learning in black-billed magpies (Pica hudsonia). Concept learning was tested with novel pictures after training. Concept learning improved with training-set size, and test accuracy eventually matched training accuracy—full concept learning—with a 128-picture set; this magpie performance was equivalent to that of Clark’s nutcrackers (a species of corvid) and monkeys (rhesus, capuchin) and better than that of pigeons. Even with an initial 8-item picture set, both corvid species showed partial concept learning, outperforming both monkeys and pigeons. Similar corvid performance refutes the hypothesis that nutcrackers’ prolific cache-location memory accounts for their superior concept learning, because magpies rely less on caching. That corvids with “primitive” neural architectures evolved to equal primates in full concept learning and even to outperform them on the initial 8-item picture test is a testament to the shared (convergent) survival importance of abstract-concept learning.
The article’s conclusion contains this passage:
So, how did the apparently primitive bird brain that evolved from dinosaurs become competitive with, and even initially outperform, the abilities of what has been considered a more elaborate primate brain to perform abstract-concept learning, which involves thoughts and processes considered to be of the highest cognitive order? The answer most certainly lies in evolution itself, a multimillion-year process. Environmental pressures (social and otherwise) undoubtedly selected for and shaped these different neural architectures to successfully accomplish many of the same essential and intelligent behaviors for survival, an example of convergent evolution in which organisms not closely related (i.e., not monophyletic) independently evolved similar traits or functions as a result of having to adapt to similar environments or ecological niches. But the example of convergent evolution presented in the current study is comparatively novel and unique because its identification required special tests of the cognitive ability (trait) for the cognitive function of fully learning a same/different abstract concept to be revealed. Other examples of convergent evolution have been based on some obvious physical trait, such as wings, which typically can be identified from fossil records and have an obvious function of flying (some insects, birds, and bats).