FRUIT flies don鈥檛 just use light to synchronise their daily activities. They can also smell what time it is.
Light is the best-known trigger for setting daily rhythms, but many animals also rely on signals from others to coordinate their activities. The mechanism behind this isn鈥檛 well understood.
Now Jeffrey Hall, a geneticist at Brandeis University in Waltham, Massachusetts, and his colleagues have shown that odour cues keep the flies punctual. Air wafted from a group of insects was enough to change the waking pattern of an isolated comrade kept in the dark, while mutant flies that could not smell their own kind stubbornly kept to their own timetable (Science, vol 298, p 2010). Whether smell plays a role in other species鈥� timekeeping is unclear, says Hall. 鈥淏ut so far the parallels between fly and human clocks have proved to be staggering.鈥�
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