A. When a honeybee discovers a rich source of nectar, she returns to the hive and performs a remarkable series of movements on the vertical surface of the honeycomb. Other bees crowd around her, and within minutes many of them leave the hive and fly directly to the flowers she has found. For centuries beekeepers had observed these movements without understanding them. It was the Austrian scientist Karl von Frisch who, beginning in the 1920s and continuing for several decades, showed that the bees were exchanging precise information about the location of food.
B. Von Frisch identified two main types of dance. When food is close to the hive, the returning forager performs a 'round dance', running in small circles and changing direction frequently. This tells her nestmates that food is nearby, but not in which direction. When the food is farther away, she performs the 'waggle dance': she runs forward in a straight line while shaking her body from side to side, then circles back to her starting point and repeats the straight run, alternating between returning to the left and to the right.
C. The straight 'waggle run' contains the key information. Its angle relative to vertical on the comb corresponds to the direction of the food relative to the sun. If the bee waggles straight upwards, the food lies in the direction of the sun; if she waggles at an angle of 40 degrees to the right of vertical, the food lies 40 degrees to the right of the sun. The duration of the waggle run indicates distance: the longer the run, the farther away the food. Remarkably, bees adjust their dances as the sun moves across the sky, so that the information remains accurate even if a dancer continues for an hour or more.
D. Von Frisch's conclusions were not accepted by everyone. In the 1960s, a group of American researchers argued that recruited bees found food mainly by following scents carried by the dancer rather than by decoding her movements. The debate continued for years, partly because it was difficult to track individual bees in flight. It was not until the early 2000s that scientists attached tiny radar transponders to recruited bees and showed that they flew in the direction indicated by the dance, even when they had been moved to a different starting point. Scent, it now appears, helps bees to find the exact flowers once they reach the right area.
E. The dance is not a perfect system. The information it provides is not completely precise, with small variations in angle from one waggle run to the next. Some researchers have suggested that this imprecision may actually be useful, as it spreads recruits over a wider area of a large patch of flowers. Moreover, bees do not always follow the dance: experienced foragers often return to sites they already know, and only a minority of bees in a hive act on any particular dance.
F. Von Frisch was awarded the Nobel Prize in 1973, sharing it with two other researchers who studied animal behaviour. Today, his work continues to inspire new research. Engineers in Germany have built a robotic bee that can perform a simplified waggle dance inside a hive, and some real bees have been observed following its directions. Such experiments not only test our understanding of the dance but may also, one day, help beekeepers guide their colonies towards crops that need pollination.