There was a very interesting paper in the journal Nature this week concerned with an issue we recently discussed in class. The paper was by Sol and colleagues and concerned absolute and relative brain size and intelligence in a sample of 111 bird species. In this study, intelligence was defined by the propensity for innovation, a measure not that different from Deaner’s measure of novel problem solving that we discussed in Lecture 01 with regard to primate intelligence. Recall that in that study, Deaner found the intelligence in primates scaled with absolute brain size rather than relative brain size (i.e., brain size scaled by body size).

The present study shows that both absolute and relative brain size predicts the propensity for innovation in birds. Moreover, it was the number of neurons in the pallial regions (prosencephalon) that were most associated with this measure of intelligence. In addition, birds with larger brains when scaled by body size tended to have more pallial neurons. Thus, both measures contributed independently to the authors measure of bird intelligence.