Why can't we all sing well? Eurovision and the science of song

The Eurovision final raises many questions, but here's a scientific one: why, when we're all capable of song, are some of us are Abba whilst others are Scooch?

The Eurovision Song Contest, the continent's annual carnival of the wacky and the weird, celebrates its 60th birthday in Vienna on Saturday night. Without it we would never have seen Russia in uproar over an Austrian drag queen, been introduced to Finnish death metal in its purest form, or witnessed the Irish attempt to win with an act called Dustin the Turkey.

It's sometimes easy to forget that beneath the costumes, the theatrics and the tactical voting, lies a talent contest. All of the Eurovision entrants intend to make an impact through the power of song, with varying degrees of success. So why is it that some carry a tune better than others?