Dodo, an extinct bird whose name has entered popular parlance as a symbol of stupidity, was actually quite intelligent, new research suggests.
The overall size of the dodo's brain in relation to its body size was on par with its closest living relatives: Pigeons - birds whose ability to be trained implies a moderate level of intelligence.
"It is not impressively large or impressively small -- it's exactly the size you would predict it to be for its body size," said lead study author Eugenia Gold from Stony Brook University in New York.
"So, if you take brain size as a proxy for intelligence, dodos probably had a similar intelligence level to pigeons. Of course, there's more to intelligence than just overall brain size, but this gives us a basic measure," Gold noted.
The researchers also discovered that the dodo had an enlarged olfactory bulb -- the part of the brain responsible for smelling -- an uncharacteristic trait for birds, which usually concentrate their brainpower into eyesight.
The study was published in the Zoological Journal of the Linnean Society.
The dodo (Raphus cucullatus) was a large, flightless bird that lived on the island of Mauritius in the Indian Ocean. They were last seen in 1662.
"When the island was discovered in the late 1500s, the dodos living there had no fear of humans and they were herded onto boats and used as fresh meat for sailors," Gold pointed out.
"Because of that behaviour and invasive species that were introduced to the island, they disappeared in less than 100 years after humans arrived. Today, they are almost exclusively known for becoming extinct, and I think that's why we have given them this reputation of being dumb," she explained.
Even though the birds have become an example of oddity, obsolescence, stupidity, and extinction, and have been featured in popular stories ranging from Alice in Wonderland to Ice Age, most aspects of the dodo's biology are still unknown.
To examine the brain of the dodo, Gold tracked down a well-preserved skull from the collections of the Natural History Museum, London, and imaged it there with high-resolution computed tomography (CT) scanning.
In the American Museum of Natural History's Microscopy and Imaging Facility, she also CT-scanned the skulls of seven species of pigeons.
When comparing the size of the birds' brains to their body sizes, Gold and collaborators found that the dodo was "right on the line" - the overall size of the dodo's brain in relation to its body size was on par with pigeons.
