Same switches program taste and smell in fruit flies. Duke Today, Feb. 3, 2016. A Duke study helps explain how fruit flies get their keen sense of smell. Researchers have identified a set of genetic control switches that interact early in a fly’s development to generate dozens of types of specialized nerve cells for smell. The findings could reveal how the nervous systems of other animals — including humans, whose brains have billions of neurons — produce a dazzling array of cell types from just a few genes.