Until now, scientists thought water moved through trees by osmosis, in a somewhat continuous manner. Now they’ve discovered the trunks and branches of trees are actually contracting and expanding to “pump” water up from the roots to the leaves, similar to the way our heart pumps blood through our bodies. The only difference between our pulse and a tree’s is a tree’s is much slower, “beating” once every two hours or so, and instead of regulating blood pressure, the heartbeat of a tree, regulates water pressure. “We’ve discovered that most trees have regular periodic changes in shape, synchronized across the whole plant … which imply periodic changes in water pressure,” András Zlinszky of Aarhus University in the Netherlands told New Scientist.