Turtle shells have built-in shock absorbers.

Singing karaokemakes most of us quickly realize how poorly we can carry a tune. Typically, when we’re confident enough to sing on stage, we’re deaf to the negative feedback. Recently, however, neuroscientist Jesse Goldberg at Cornell University, USA, discovered a brain region that listens and produces a chemical ‘booing’ when birds sing off key. Vikram Gadagkar and colleagues in the Goldberg lab report that a special group of dopamine neurones in bird brains critically evaluate and encourage when birds chirp well.