Quirks & Quarks

Crocodile Bach - what classical music does to a reptile's brain

Playing classical music like Bach to crocodiles sheds light on the evolution of brain structure and the processing of complex sounds
When a crocodile listens to complex sounds like classical music, brain patterns are activated that are similar to those of birds and mammals, including humans (Getty Images)

The crocodile brain

Scientists, including Dr. Felix Strockens from the department of biopsychology at Ruhr University in Bochum, Germany, wanted to study the crocodile brain for a couple of reasons. One was that crocs are among the most ancient species of vertebrates and have not changed much in more than 200 million years. Another reason is crocodiles provide a link between dinosaurs and modern birds. Because of this link, understanding the crocodile brain provides insight into the evolution of the mammalian nervous system and may also shed light on when certain brain structures and related behaviours were formed. 

How to train your crocodile

For the experiment, and for the first time ever, a cold blooded reptile was placed in an fMRI scanner. The sedative normally used for humans didn't work on the crocodile, so an alternative approach was needed. Rather than sedate the crocodile, it was placed in a large tube, then moved into the scanner. Fortunately, the crocodile liked the darkness of the tube and remained very calm and still for the duration of the scan. While in the fMRI, the crocodile was exposed to various auditory and visual stimuli, including classical music.   

Ah, Bach!

As the crocodile listened to Johann Sebastian Bach's Brandenburg Concerto #4, the researchers measure the animal's brain activity. Classical music, and this piece in particular, was chosen because of its complex nature. The results of the scan show that additional brain areas are activated during exposure to complex sounds, like Bach, compared to the brain areas activated by simple sounds, such as those the crocodile would hear in a natural setting. The way the crocodile processes sound strongly resembles the sound processing patterns identified in earlier studied of mammals and birds. This suggests that this particular brain function formed at an early evolutionary stage and likely has the same origins in all vertebrates.