We have tended to assume that intelligence rose with the development of a spinal cord and brain (vertebrates), and warmbloodedness (mammals and birds).
Explaining the origin of complex phenotypic novelty is the million-dollar question in evolutionary biology.
These findings are only among birds that have actually been studied; most birds have not been studied for intelligence.
Not only racism, but racial extermination was an integral feature of Darwin’s theory from the start.
Is it possible that adaptive radiation is falling out of the Darwin trophy cabinet? A new proposal sounds amenable to intelligent design.