Wednesday, July 29, 2015

#88 The Waggle Dance of Honeybees

I think you are probably familiar with the game of Charades where one person tries to act out a phrase while other members of his/her team try to guess the meaning.

Let’s suppose that the message you are given to act out is the exact location of tonight’s dinner for everyone which it so happens is a couple of miles away.

Remember, you cannot speak and you cannot write. It’s pretty important that you can convey this information or you might all go hungry and eventually die.

Oh, and just to make it a little more tricky, let’s just say that we shrink your communication ability down to the level of a honeybee and similarly for those receiving the message.

Sounds really, really difficult, right? Well, just how do bees do it successfully all the time?


Please watch this National Geographic video (less than 2 minutes) to see a great summation of how they accomplish it. [1] As you might have guessed from the title, they do a little dance.

The Theory of Evolution might say that given millions of years and thousands of generations, the precise method to communicate where the food is located had to (1) accidentally get acted out one day by one honeybee in some way that was (2) correctly understood by another bee. The second one who understood the message, (3) flew off in the right direction and (4) to the right distance and found food. Somehow this accidental communication of information (5) was passed on to other bees in the hive and then (6) passed on to the next generation and ultimately (7) to all honeybees in the world.

I’m having a little trouble imagining that this could happen (sarcasm intended).

Around 40 years ago a scientist, named Karl von Frisch, a professor of zoology at the University of Munich in Germany, discovered the communication technique of honeybees. He set up a very ingenious experiment. He created two honeybee feeders and set them in totally different directions and distances from the hive. Then when bees eventually arrived at the feeders, he painted little spots on them so he knew which ones visited that feeder. He was able to film their actions inside the hive. That is when he discovered what has been named the Honeybee Waggle Dance. He was later given the Nobel Prize for Medicine in 1973 for his work.

Wikipedia says, “Waggle dance is a term used in beekeeping and ethology for a particular figure-eight dance of the honey bee. By performing this dance, successful foragers can share, with other members of the colony, information about the direction and distance to patches of flowers yielding nectar and pollen, to water sources, or to new nest-site locations.” [2]

Von Frisch discovered that the honeybee will do a short wiggling dance in a straight line, then stop wiggling. It will swing around to the right and circle back to its original starting point for the dance and then do it all over again. However, the second time when it gets to the end, it will swing around to the left and circle back to the beginning point.

Von Frisch was able to determine that the precise axis the bee is traveling during the dance section tells the other bees the direction to fly in. He also discovered that the number of waggles during the dance was communicating the distance that they should fly.


“While running the straight-line course of the dance, the bee’s body, especially the abdomen, wags vigorously from side to side. This vibration of the body produces a tail-wagging motion. At the same time, the bee emits a buzzing sound, produced by wingbeats at a low audio frequency of 250 to 300 hertz or cycles per second.” [3]

But it is much more amazing than you might first think, although this is totally amazing already. The bee hive is usually built vertically. However, the direction that the bees have to fly will be a horizontal direction. Somehow the bee doing the dance has to be able to take the horizontal direction and distance information and convert it in her brain before she does the dance on a vertical surface. Also, the bees receiving the information have to be able to convert it in their brains back into the original information horizontally.


Von Frisch discovered that the dance being done on the vertical hive surface was using gravity as a reference point and that straight up represented the location of the sun and straight down represented 180 degrees away from the sun.

Here is an outstanding animated video from Georgia Tech College of Computing (7.5 minutes) that illustrates the experiments of Karl von Frisch and demonstrates how bees communicate. [4]

If the axis of the waggle dance was 30 degrees off of the vertical to the right, then the other bees were able to understand that they should take the position of the sun and then fly exactly 30 degrees to the right. Amazing that they can know the exact angle, right?

“The distance between hive and recruitment target is encoded in the duration of the waggle runs. The farther the target, the longer the waggle phase. The more excited the bee is about the location, the more rapidly it will waggle, so it will grab the attention of the observing bees, and try to convince them. If multiple bees are doing the waggle dance, it's a competition to convince the observing bees to follow their lead, and competing bees may even disrupt other bees' dances or fight each other off.” [5]


Now you must be smart enough to realize a big problem…namely the sun keeps moving all day long. Even more challenging is that the arc of the sun is not the same every day but changes in the sky according to the seasons. If the bees live south of the equator, you have to flip things over.

Not only does the sun moving in the sky make it difficult, but sometimes it is so cloudy that we can’t see the sun. Astoundingly, the bees are able to see ultraviolet light, which penetrates the cloud cover. 



So they can see the sun at all times. Not only that, but even more bewildering for a non-believer is that the honeybee’s eyes polarize the sunlight like polarized sunglasses. That means they can even more accurately identify the exact direction of the sun.


The bees have a finely tuned internal clock (Where did they get that?) so a dancing bee who has been in the darkness of the nest for a while somehow calculates where the sun is going to be when their fellow bees head off from the hive. The axis of its dance has to change because the sun moved in the sky. Not only that of course, but those leaving the hive are going to be continually calculating changes to the direction they should fly according to the amount of time that has elapsed and the change in position of the sun.

Here is another video. This one is loaded with film footage of bees at work and what their eyes are really seeing. (5min, 18sec.) [6]

The bee also communicates a second very important piece of information…the distance to fly to get to the food source. This is done by either the number of waggles or the length of time waggling. Researchers now estimate that one second of waggling equals one kilometer of distance. If the food source is close, there is no waggling at all, but just a circling around motion.


"While several variables of the waggle dance relate to distance (such as dance “tempo” or the duration of buzzing sounds), the duration of the straight-run portion of the dance, measured in seconds, is the simplest and most reliable indicator of distance. As the distance to the food source increases, the duration of the waggling portion of the dance (the “waggle run”) also increases. The relationship is roughly linear. For example, a forager that performs a waggle run that lasts 2.5 seconds is recruiting for a food source located about 2,625 meters away." [7]

But note that scientists have observed that if there is a strong headwind coming from the direction of the food source, the bee will have to fly a longer time to reach the destination. The waggle dance will last longer. This leads scientists to believe that the bees are not measuring the distance to fly but the amount of energy it takes to get to the food source.

The forager bees who do the waggle dance also bring back on their legs and abdomen some of the food source that has been discovered. So the other bees are able to sample what their goal is at the distant location. So smell may also be a strong component of the communication.


Scientists know the waggle dance is real, so bees really in fact can do this. However there is controversy about how much it is effectively used by other bees, with estimates as low as 10% of other bees actually using the data.

The simplest and most elegant explanation for the waggle dance is that it was designed by the Creator of the Universe, an unimaginably superior intelligence. If you decide against there being a Creator, then you have to posit some other explanation which must be based on pure accident and random happenstance coming together in a fortuitous way. Then another random accident brings another fortuitous result. This pattern repeats itself again and again, thousands or more accurately millions of times. Notwithstanding that this violates the laws of nature and probability, you must imagine and try to believe that’s how it happened because, voila, the truth is that scientists have now discovered these facts of how bees communicate using the waggle dance.

I’ll stick with, there must be a God.
________________________________________

[1] National Geographic video, World’s Weirdest: Honeybee Dance Moves, http://video.nationalgeographic.com/video/weirdest-bees-dance

[2] Wikipedia, “Waggle Dance”, https://en.wikipedia.org/wiki/Waggle_dance

[3] N.C. State University, The Honey Bee Dance Language, http://www.cals.ncsu.edu/entomology/apiculture/pdfs/1.11%20copy.pdf

[4] Georgia Tech College of Computing, Video: The Waggle Dance of the Honeybee, https://www.youtube.com/watch?v=bFDGPgXtK-U

[5] Wikipedia, “Waggle Dance”, https://en.wikipedia.org/wiki/Waggle_dance

[6] wgbhstocksales Video: Bee Waggle Dance, https://www.youtube.com/watch?v=Jc-mtUs-eis

[7] N.C. State University, The Honey Bee Dance Language, http://www.cals.ncsu.edu/entomology/apiculture/pdfs/1.11%20copy.pdf



1 comment:

  1. That's a lot of information for me to take in let alone a honeybee. Thank you for taking the time to put this research together.

    ReplyDelete