Who is There?
Susan Lahey begins a recent Popular Mechanics article with a wonderfully destabilizing possibility: we may be surrounded by trillions of conscious beings and simply have failed to notice them. She means plants. The evidence she surveys is fascinating. Plants respond to their environments in ways considerably more complicated than we once imagined. Some communicate chemically. Some appear capable of habituation. A Mimosa pudica , repeatedly subjected to a harmless disturbance, may eventually cease its defensive response. Plants respond to anesthetics. Trees under attack can release chemical signals that alter the behavior of neighboring trees. Beneath a forest floor, roots, fungi, microorganisms, water, and nutrients participate in networks of extraordinary complexity. From such observations, some researchers have begun asking whether words such as learning , memory , cognition , and even consciousness might properly apply to plants. A still more adventurous proposal asks whether...