In February1954, a US biologist named Frank Brown discovered something so remarkable, so inexplicable, that his peers essentially wrote it out of history. Brown had dredged a batch of Atlantic oysters from the seabed off New Haven, Connecticut, and shipped them hundreds of miles inland to Northwestern University in Evanston, Illinois. Then he put them into pans of brine inside a sealed darkroom, shielded from any changes in temperature, pressure, water currents, or light. Normally, these oysters feed with the tides. They open their shells to filter plankton and algae from the seawater, with rest periods in between when their shells are closed. Brown had already established that they are most active at high tide, which arrives roughly twice a day. He was interested in how the mollusks time this behavior, so he devised the experiment to test what they would do when kept far from the sea and deprived of any information about the tides. Would their normal feeding rhythm persist?
For the first two weeks, it did. Their feeding activity continued to peak 50 minutes later each day, in time with the tides on the oysters’ home beach in New Haven. That in itself was an impressive result, suggesting that the shellfish could keep accurate time. But then something unexpected happened, which changed Brown’s life forever.
The oysters gradually shifted their feeding times later and later. After two more weeks, a stable cycle reappeared, but it now lagged three hours behind the New Haven tides. Brown was mystified, until he checked an astronomical almanac. High tides occur each day when the moon is highest in the sky or lowest below the horizon. Brown realized that the oysters had corrected their activity according to the local state of the moon; they were feeding when Evanston—if it had been by the sea—would experience high tide. He had isolated these organisms from every obvious environmental cue. And yet, somehow, they were following the moon.
For a while, Brown’s experiment became infamous, one of the most controversial results in biology. Scientists were just starting to appreciate that living processes vary according to environmental cycles such as the time of day, but every other major figure in the field was convinced these rhythms are ultimately driven by internal clocks; Brown’s lone insistence that organisms are plugged into mysterious cosmic cues was widely dismissed. The disagreement reflected a deeper, philosophical split regarding the relationship that living creatures have with our planet and the wider cosmos. Are we autonomous, self-running machines, or is life in constant, subtle communication with the Earth, sun, moon, and even stars?
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Brown decided to investigate the most fundamental biological process he could think of: metabolism. He studied sprouting potatoes—in experiments that ran for years—as well as bean seeds, mealworm larvae, chick eggs, and hamsters, shielding them all from changes in temperature, pressure, and light. Although they were supposedly cut off from the outside world, he saw patterns in their metabolic rate that matched not just the movements of the sun and moon, but pressure and weather changes in the Earth’s atmosphere. Even the potatoes “knew” not just the hour but the season of the year. It was as if life were pulsing in time with the planet.
Brown concluded that the organisms were sensitive to external geophysical factors, perhaps minute fluctuations in gravity, or even subtle forces that hadn’t yet been discovered. In his rivals’ experiments, supposedly proving the existence of independent clocks, Brown argued that the subjects weren’t cut off from the environment after all. They were bathed in—and influenced by—subtle, rhythmic fields that varied as the Earth turned.
Such ideas were viewed as threatening by his peers. Several of them had fought to have their own work on daily cycles taken seriously by other scientists. Their professional respectability hinged on using rigorous, reproducible methods, and basing their theories on impeccable physical principles of cause and effect; Brown’s claims of mysterious forces were dangerous nonsense that jeopardized the field. His measurements weren’t accurate enough, they insisted, or he was seeing patterns in his highly complex data that simply weren’t there. Yet Brown was charismatic and articulate, and he was swaying public opinion.
Something had to be done.
The first major blow came in 1957, with an extraordinary paper in the leading US scientific journal, Science, in which a respected ecologist named LaMont Cole claimed that by juggling random numbers, he had “discovered the exogenous rhythm of the unicorn.” The satire was aimed at Brown and his team, and its message was clear: Their results were as imaginary as the unicorn itself. It was an unprecedented, personal attack and it “hit us very hard,” Brown recalled later. “We were everywhere encountering innuendos from this article.” In 1959, Halberg followed up by coining the term that now defines the field: “circadian.”
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