Fly may hold key to human condition

Do you enjoy dining out, far from the reach of home cooking? The reason could be genetic, especially if you happen to be a fruit fly, researchers reported yesterday.

A single gene appears to determine whether fruit flies - and possibly mammals, including humans - like to forage for food far away or prefer eating close to home, according to Marla Sokolowski, a biologist at York University in Toronto.

The fruit fly world is divided into two distinct types, rovers and sitters, Ms Sokolowski and colleagues wrote in this week's edition of the journal Science. Rovers are willing to travel farther for food than the sitters, but both types will roam if food supplies are scarce enough. And rovers will stay home to eat if conditions are right. The genetic basis of the trait means this is a true bimorphism: flies fall into one or the other category, with none who sometimes rove and sometimes sit. Rovers can be turned into sitters only with genetic intervention or drastic measures such as application of gamma radiation, which causes the gene to mutate. The chance that humans have a similar gene is quite good, Ms Sokolowski said.