Why do we crave chocolate, and what happens to aeroplane toilet waste?

We explore the curious questions that science can answer

The real question is why would we not crave something sweet that melts in the mouth? (Getty/iStock)

Why do we crave chocolate?

Chocolate contains large amounts of phenylethylamine, which is also present in our bodies and released during sexual arousal, heightening sensation and raising the heart rate. It also contains methylxanthine and theobromine, which have similar effects to caffeine. And if that isn’t enough, it is solid at room temperature but melts at just below body temperature – that is, in your mouth.

Why don’t the chocolate chips in cookies melt during cooking?