The Waggle Dance Gets Bees Moving

Finding a new home can be a difficult process, but any family wanting to do so intelligently -- without trying to kill each other -- might benefit by learning how to do the waggle dance.

Especially if the family has as many as 10,000 members.

Honey bees make those decisions all the time, and the methods employed by these highly organized social colonies have long intrigued and mystified scientists.

How do honey bees, or any society for that matter, subvert the will of the few in the interest of the many? Or more precisely, as scientists have recently learned, how do bees make the right collective decision nearly all of the time, at least when it comes to picking a new home?

That may not seem like a particularly pressing question, but scientists want to know the answer because group decision-making processes affect all of our lives.

Whether it's a family searching for a new home, or the U.S. Congress trying to pass a budget, how decisions are made is a complex, and often wrong, process.

That's why for decades now scientists have turned to honey bees for a little help. A report in the current issue of American Scientist spells out the latest research.

"The fundamental decision-making dilemma for groups is how to turn individual preferences for different outcomes into a single choice for the group as a whole," says Thomas D. Seeley, professor of neurobiology and behavior at Cornell University.

Seeley, along with entomologist Kirk Visscher of the University of California-Riverside, and Ohio State University engineer Kevin Passino, have been studying honey bees for more than a decade now, and they've confirmed and enlarged upon previous research showing that for bees, the waggle dance is everything.

More than half a century ago scientists in Germany learned that when a scouting bee returns to the nest after finding a new source of food, she goes through a series of gyrations called the "waggle dance."

She flies forward, vibrating her abdomen laterally, and then returns to her starting point, completing one circuit. The number of circuits she completes tips off the rest of the bees as to the quality of the resource.

A Democratic Dance

The German researchers learned later that the waggle dance also played a role in the selection of a new home, but it was unclear exactly how that process played out. Over the years other scientists have picked up that theme, but questions remained.

Do the bees reach a decision through a democratic process in which the majority rules? Does everybody have a voice? Do they nearly always get it right?

The answer to all those questions is "yes."

"This is a striking example of decision making by an animal group that is complicated enough to rival the dealings of any department committee," Seeley says.

It happens every year when a colony outgrows its nest and the queen bee takes off with about half the hive in search of a new home. The bees form a heart-shaped swarm, usually in a nearby tree, while hundreds of scouts are sent off to find a new location.

Usually, several potential sites are found, and the scouts return to the swarm and perform the waggle dance. Researchers have found, however, that not all waggle dances are the same.

If the site is only mediocre, for example, the scout may only complete a few circuits of the dance. If it's a dandy prospect, however, she may do 100 or more.

The scout from the mediocre site will go forth again, either back to her first choice, or to another site, and return once again to the swarm.

If she has just revisited the earlier site, her dance will be even less vigorous than the time before. But if she has opted to join other scouts at a superior site, she'll get into the movement with gusto, completing far more circuits.

That process continues until one of the sites has a "quorum" of at least 15 scouts that remain there. At least 150 other scouts zip back and forth between the site and the swarm, carrying the message that a quorum has been reached.

The scouts pass the word through a technique that is not likely to be emulated in Congress, or any other lofty body. Each scout moves through the swarm, pressing her vibrating thorax against the other bees. That apparently tells them to warm up their flight muscles and get ready to move out.

The bees flex their muscles until they reach a temperature of 95 degrees Fahrenheit. That produces an "audible vibration that is reminiscent of the revving of a race car engine," the researchers report. At that point the entire swarm takes off for the new home. A decision has been made, but was it the right one?

Seeley and his colleagues traveled to an island in the Gulf of Maine to find out. They set up a number of potential nests on the treeless island, some of which were small and mediocre, and one that was larger and superior.

Scouting bees found all the sites, although they rarely found the best site first. Then through a process of elimination, they settled on the best site nearly every time. The rest of the process remains somewhat of an "enigma," the researchers say, but the bees somehow sensed that a quorum had been reached.

The system works, the researchers say, because no scout was excluded from the process.

"A swarm's decision-making process is broadly diffused among all the scout bees in a swarm," they say. "Consequently, a swarm's decision-making process is based on the actions of hundreds of individuals, each one an autonomous agent capable of providing unique information for solving the house-hunting problem.

"Searching independently, widely and simultaneously, the hundreds of scout bees from a swarm bring back to the group diverse information -- the knowledge of superb, mediocre and even lousy sites -- which can be shared with the other scouts by means of waggle dances. All discoveries of potential nest sites are freely reported; no scout is stifled."

A great site results in terrific waggle dances, allowing the swarm to "avoid mass manias over poor options."

The keys to success, the researchers say, are an open competition of ideas, "promoting diversity of knowledge and independence of opinions among the group's members."

It works for the bees because everybody has a voice, and all the options are explored, and in the end the majority rules.

So could that work in Congress?

Undoubtedly, but let's skip the waggle dance.