Scientists Learn How Bumblebees Solve Complex 'Traveling Salesman Problem' So Effortlessly
Scientists have always known that in order to forage for nectar as efficiently as they do, the tiny bumblebee had figured out the perfect solution to what is commonly referred to as 'The Traveling Salesman Problem' - that is figuring out the shortest routes from flower to hive. While this may sound simple it is actually a complex mathematical problem given that there are hundreds of different routes - One that takes even humans with their 'superior' brains seek out the help of computers to solve!
In the past, scientists had theorized that the tiny insect did this by using cognitive maps - That is by memorizing the surroundings inside its tiny brain. However, nobody had ever observed the insects closely enough to verify if this indeed was the case, until recently.
A group of researchers from Queen Mary, University of London, began by selecting seven bumblebees and sticking tiny radar transponders onto their backs. They then trained them to seek out nectar from five artificial flowers - each equipped with a yellow landing platform. To ensure that every bumblebee visited each flower before they headed back to the hive, they filled them with just one drop of sucrose, exactly one-fifth of the insect's nectar carrying capacity.
In October of 2011, once the bees were 'trained', the scientists transplanted the flowers in a field near their research center in London. The timing was very strategic because it was fall, a time of the year when foraging options for the bees were limited, which helped ensure that they would gravitate towards the artificial flowers that they knew for sure, contained nectar.
To ensure that they would have to fly around and search for each flower, the researchers placed them more than 50 meters apart - A distance three times greater what the bees can normally see. Finally, they attached a motion-triggered camera to each flower so that every visit could be recorded.
After the stage was set they began the experiment. With the scientists recording every movement, one bee was set free each day and allowed to forage for seven hours. Once every insect's trajectory, travel distance and speed had been collected they ran some mathematical models to calculate how the bees had managed to figure out the shortest distances from the flower to the hives. What they discovered was quite fascinating, because it involves mathematical calculations that even humans with computers have a hard time solving.
Initially, each bee began in the same way - visiting the closest flower first and then the next one and so on and so forth. This of course was a rather long and laborious route which often resulted in them visiting empty flowers over and over again. But the tiny insects seemed to realize that in no time at all and soon began to experiment with new routes - if it helped increase their speed and efficiency they remembered it, if not, they quickly discarded it from their memories.
What was the most interesting to the researchers was that out of the 120 possible routes, the bees only needed to try 20 to figure out the most efficient and shortest one. So while the first time the bee would travel about 2,000 meters, by the final attempt it would have figured out how to reduce it to less than 500! What surprised the scientists the most was not only how quickly they were able to deduce the shortest route, but also, that they were able to remember it all inside their tiny brain that contains less than one million neurons!
Of course, while the study was fascinating just on its own it was done with an ulterior motive in mind - How to help route-planning for robots that are exploring unfamiliar terrain or software bots that are navigating the Internet - Something that will benefit us all, eventually!
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