few years ago, the Rosenbergs stumbled across an old paper from 1989, in which a biologist named Diane Dodd showed that a fly’s diet could affect its sex life. She reared one strain of fruit flies on starch and another identical strain on maltose, a type of sugar. After 25 generations, the ‘starch flies’ preferred to mate with other starch flies, while the maltose flies were biased towards their own kind. It was a weird result. By changing the flies’ diet, Dodd had somehow altered their sexual preferences.
