IN FEBRUARY 1954, biologist Frank Brown discovered something that made no sense. While investigating whether oysters can keep time, he had found that they open their shells to feed at high tide, roughly twice a day. Brown had a hunch they weren't simply responding to changes in their environment but would continue the rhythm even if moved far from the sea. To find out, he shipped a batch of oysters from the ocean off New Haven, Connecticut, hundreds of kilometres inland to Northwestern University in Evanston, Illinois. Brown kept the shellfish in a sealed darkroom, shielded from changes in temperature, pressure, water currents and light. At first, the oysters kept their rhythm, feeding each day in time with the New Haven tides. Then, something strange happened -their feeding times gradually shifted until they lagged 3 hours behind. Brown was mystified, until he realised that they had adapted to the local state of the moon: they were feeding at times when Evanston, if it were by the sea, would experience high tide. Despite having no obvious environmental cues, it seemed these shellfish were somehow tracking lunar cycles.
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