The Dodo May Not Have Been a Dodo

The word "dodo" has long been a synonym for "stupid." In fact, "dodo" comes from "doudo," the Portuguese word for "stupid." The large, flightless Dodo bird (Raphus cucullatus), once native to the Indian Ocean island of Mauritius, went extinct about 400 years ago, less than 100 years after it was discovered by humans. Popular culture blames the bird. However, new research suggests that the Dodo might have been at least as smart as the pigeons to which it was related.

In a recent article in the Zooligical Journal of the Linnean Society Dr. Eugenia Gold and her team at the National Museum of Scotland and the Natural History Museum of Denmark describe how they went about reimagining the Dodo's cognitive capacity.

Dr. Gold and her team started with a well-preserved skull from the National History Museum in London, which they imaged with high-resolution computer tomography (CT) scanning. They then used CT scanning to capture images of the skulls of seven species of pigeons plus the Dodo's closest relative, the Rodrigues Solitaire (Pezophaps solitaria), another extinct island-dwelling bird. From these scans, the team built virtual endocasts (casts of the braincase) to determine the overall brain size and the size of different brain structures in the different species.

Among their findings: the Dodo's brain was in about the same proportion to its body as a pigeon's. This means that the Dodo may have been about as bright as a pigeon. Since pigeons are smart enough to be trained, the implication is that Dodos may have possessed a moderate level of intelligence. Of course there's more to intelligence than brain size, but it's a good start.

One unexpected finding was that the olfactory bulb–the part of the Dodo's brain responsible for smell—seemed to be enlarged. This is unusual in birds, which typically have brains developed for keen eyesight. The Rodrigues Solitaire had a similarly enlarged olfactory bulb. Gold and her team suggest that, being flightless land-dwellers, Dodos and Solitaires may have depended on their sense of smell rather than their eyesight to hunt for food. 

One rather mysterious result: the research team discovered a strange curvature in the Dodo's semicircular canal—the balance organ in the ear. The team has yet to find a good hypothesis for this feature.

Want the whole story? Check out the team's findings in the Zoological Journal of the Linnean Society.