Inside the pitch-dark crowd of a beehive, a forager returns from a rich patch of flowers and begins, improbably, to dance. She runs in a straight line while waggling her abdomen from side to side, loops back, runs the same line again, and repeats — a figure-of-eight traced across the vertical comb. Around her, other bees press close, following her movements in the darkness. Then some of them fly off, straight to the flowers she found, perhaps kilometres away. This is the waggle dance, and its decoding stands as one of the most astonishing discoveries in the history of biology: proof that an insect can tell another insect where to go.
Cracking the code
The man who worked it out was the Austrian ethologist Karl von Frisch, over decades of patient observation beginning in the early twentieth century. Von Frisch set up glass-walled observation hives, marked individual bees with tiny spots of paint, put out feeding dishes at known distances and directions, and watched, again and again, what a successful forager did when she came home. Slowly a code emerged, and it was breathtakingly elegant.
The waggle dance encodes two pieces of information: the direction of the food and its distance. The direction is conveyed by the angle of the straight "waggle run" relative to vertical on the comb. Here is the clever part. The bees translate the position of the sun into the pull of gravity. A waggle run pointing straight up the comb means "fly towards the sun"; a run pointing straight down means "fly away from the sun"; and a run angled, say, forty degrees to the right of vertical means "fly at forty degrees to the right of the sun's direction." The vertical of the dark hive stands in for the sun outside.
The distance is encoded, roughly, in the duration of the waggling portion of the run — the longer and more vigorously she waggles along that straight run, the further away the food. A short waggle means flowers close by; a long one means a journey. The watching bees read both numbers off a single dance and set out with a heading and a range, like following a compass bearing and an odometer reading given in body language.
The sun that moves, and the argument that followed
There is a further subtlety that makes the feat even more remarkable. The sun moves across the sky through the day, so a direction given relative to the sun in the morning would be wrong by the afternoon. Bees compensate. Using an internal clock, a bee that dances over a long period will gradually shift the angle of her waggle run to keep track of the sun's changing position, so the instruction stays accurate. A bee can even dance correctly for a food source when the sun is hidden behind cloud, reading the sun's position from the pattern of polarised light in patches of blue sky, to which bee eyes are sensitive.
Von Frisch's conclusion — that a mere insect possessed a symbolic language capable of communicating abstract information about a distant place — was so extraordinary that some scientists resisted it for years, proposing that recruits found the food by smell rather than by reading the dance. The debate ran for decades and was eventually settled decisively in the dance's favour, including by experiments using tiny robotic bees programmed to "dance" and thereby direct real foragers to chosen spots. In 1973 von Frisch was awarded the Nobel Prize in Physiology or Medicine, sharing it with fellow animal-behaviour pioneers Konrad Lorenz and Nikolaas Tinbergen — a rare Nobel awarded, in effect, for learning to read the language of animals.
The waggle dance remains one of the very few known examples of an animal using a genuine symbolic code to refer to something not present — a distant, invisible place described in the abstract terms of angle and duration. A creature with a brain smaller than a grass seed carries a map of its world and can hand that map to its sisters in the dark, by dancing. Von Frisch's great achievement was not the bees' cleverness, which was always there, but the humility and patience to sit at the glass, year after year, and finally understand what they had been saying all along. The bees had been giving directions since before there were humans to overhear them; it simply took one very attentive listener to work out the grammar.
Quiz nuggets
- The honeybee waggle dance was decoded by Austrian ethologist Karl von Frisch over decades of observation.
- The angle of the straight "waggle run" relative to vertical on the comb encodes the direction to food relative to the sun.
- The duration of the waggling portion encodes the distance to the food source.
- Bees compensate for the sun's movement using an internal clock and can read the sun's position from polarised light on cloudy days.
- Von Frisch won the 1973 Nobel Prize in Physiology or Medicine, shared with Konrad Lorenz and Nikolaas Tinbergen.