Social structure is link structure is intelligence.

In a growing recognition of the genius of birds, scientists are now studying various birds to explore everything from spatial memory to the grammatical structure of human language. This research is helping to reveal the secrets of the human brain. But it is also overturning the conventional evolutionary story of intelligence, in which all paths lead to the creation of the human cortex. The tree of life, scientists are discovering, has numerous branches of brilliance.

Intricate social structures mean that many birds are subject to the same social challenges as primates. It is these challenges, the research suggests, that make them so smart.