We know that birds evolved from dinosaurs around 150 million years ago, but we still don't know how birds first gained the ability to fly. But a part of the bird brain that controls flight could solve this evolutionary riddle.
Towards the rear of birds' brains is the flocculus, a substructure of the cerebellum that handles visual and balance information during flight, making it possible for birds to know where other objects are located while they're flying and avoid any midair crashes. According to Stig Walsh of National Museums Scotland, tracking the size and shape of the flocculus throughout birds' evolutionary history could reveal when birds first gained the ability to fly:
"We believe we can discover how the flocculus has evolved to deal with different flying abilities, giving us new information about when birds first evolved the power of flight. We are particularly interested in species that are closely related where there are flying and flightless examples, such as cormorants, pigeons, parrots and ducks."
They hope to discover whether the flocculus gets smaller as bird species lose the power of flight, as obviously they no longer have to judge where other objects are in the air. Along with over 100 flighted and flightless modern birds, the researchers are examining preserved brains from extinct species, including the relatively recent remains of a 17th century dodo, a Cretaceous seabird that lived 100 million years ago and lacked flight, and the oldest known flying bird Archaeopteryx.
If the size of the flocculus really does correlate with how well birds can process visual and balance information during flight, then that could provide a very powerful tool for measuring the path of bird evolution. It might allow researchers to understand when ancient birds first evolved flocculuses large enough to sustain flight, and it will also help us understand whether ancient bird-like fossils were flightless birds or, in fact, dinosaurs that never gained flight in the first place.
The researchers still have a lot of work to do - the results won't be out until 2012 - but Walsh suspects that, whatever they discover, this won't be the end of the story by any stretch:
"With the heated debate about these animals, this would be an excellent finding, though I'm sure the debate won't end there."