“A male fruitfly will try to court a female by nuzzling her genitals, tapping her abdomen and singing with his wings. If all that fails, he drowns his sorrows in booze.”

That’s how my latest piece for Nature News starts. It’s obviously a cute result, but there’s some serious and intriguing science underlying it. These twin rewarding activities – sex and drinking – are linked by a chemical called neuropeptide F (NPF), which acts as a sort of currency of reward in the brain.

The study suggests that NPF is part of a system that acts like a ‘reward-thermostat’. If flies aren’t getting rewarding feelings from sex, their levels of NPF fall, and this compels them to get their kicks elsewhere,