Word: sweetgum
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Dates: during 1970-1979
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Writing in the journal Science, Neel and Harris explain the simple procedure that they used to test their hunch. At a local nursery, they bought eight matching pairs of young sweetgum trees. They potted the sweet gums in four-gallon cans in their greenhouse and stopped in every morning to give one member of each pair a brisk 30-second shaking. After 27 days of this routine, the shaken trees had grown only one-fifth as much as those left in peace, had put out fewer lateral branches and developed stouter, tougher trunks. Trees, conclude the authors, have evolved...