The Ash Twins Blog

The common crow is a surprisingly intelligent creature. Consider this experiment: Catch a crow and wait until he is hungry. Place a tasty treat in a cup narrow enough that the crow won’t be able to fit his beak into it. Then, give the crow a straightened paper clip.

Before long, the hungry crow will pick up the paper clip and jab it down into the cup, attempting to impale the treat. If the treat is so slippery that this spearing strategy won’t work, the crow will eventually curve the end of the paper clip to form a hook. He’ll fish out the treat and claim his prize.

All of this with only a rudimentary cerebral cortex. After reptiles and mammals diverged, mammals evolved the layered-and-folded structure known as the neocortex, the incredible size of which in primates is believed to underlie problem solving skills. Reptiles and subsequently birds, on the other hand, evolved a unique deep brain nucleus called the dorsal ventricular ridge, which has no obvious homologue in mammals. In intelligent birds (like corvids and parrots), the dorsal ventricular ridge is massive, and has evolved connections, organization, and functions surprisingly similar to that of the neocortex in mammals.

Source: Striedter (2008) Principles of Brain Evolution